G. A. E. Vandenbosch [references] [full-text] [Download Citations]
Efficient Procedure for the Calculation of Electric and Magnetic Energies in Vacuum

New expressions are derived to calculate the reactive energy stored in the electromagnetic field surrounding an electromagnetic device. The resulting expressions are 1. very simple to interpret, 2. general, 3. rigorous in terms of the currents flowing on the device, and 4. fast since they involve integrals solely over the device generating the field. The new technique is very feasible to be used in cases where the electric and magnetic reactive energies are important in practice, for example in the case of resonators, or in the case of radiating structures. Used there, they allow to study in a rigorous way the effect of the shape of the device on the amount of reactive energy, and thus for example on the Q of the device. The implementation of the new expressions in numerical CAD tools is extremely simple and straight-forward. In this paper, the expressions are derived for sources in the homogeneous medium vacuum, but this is not a fundamental restriction.

1. COLLIN R. E., ROTHSCHILD, S. Evaluation of antenna Q. IEEE Transactions on Antennas and Propagation, 1964, vol. AP-12, p. 23-27.
2. CHU, L. J. Physical limitations on omni-directional antennas. Journal of Applied Physics, 1948, vol. 19, p. 1163-1175.
3. FANTE, R. L. Quality factor of general ideal antennas, IEEE Trans. Antennas & Propagat., March 1969, vol. AP-17, p. 151 to 155.
4. MCLEAN, J. S. A re-examination of the fundamental limits on the radiation Q of electrically small antennas. IEEE Transactions on Antennas and Propagation, 1996, vol. 44, p. 672-676.
5. STEN, J. C.-E., HUJANEN, A., KOIVISTO, P. K. Quality factor of an electrically small antenna radiating close to a conducting plane. IEEE Transactions on Antennas and Propagation, 2001, vol. 49, p. 829-837.
6. GEYI, W. A method for the evaluation of small antenna Q. IEEE Transactions on Antennas and Propagation, 2003, vol. 51, p. 2124-2129.
7. SHLIVINSKI, HEYMAN, E. Time-domain near-field analysis of short-pulse antennas – part II: Reactive energy and the antenna Q. IEEE Transactions on Antennas and Propagation, 1999, vol. 47, p. 280-286.
8. COLLARDEY, S., SHARAIHA, A., MAHDJOUBI, K. Calculation of small antennas quality factor using FDTD method. IEEE Antennas and Wireless Propagation Letters, 2006, vol. 5, p. 191-194.
9. Katholieke Universiteit Leuven, Belgium. MAGMAS – the TELEMIC Antenna Modelling Software. [Online] Cited 2009-11-10. Available at http://www.esat.kuleuven.be/telemic/antennas/magmas .
10. YAGHJIAN, D., BEST, S. R. Impedance, bandwidth and Q of antennas. IEEE Transactions on Antennas and Propagation, 2005, vol. 53, p. 1298-1324.

Keywords: Electric and magnetic energy, Q factor, small antennas.

S. R. Best [references] [full-text] [Download Citations]
The Quality Factor of the Folded Cylindrical Helix

Any electrically small antenna can be impedance matched at any single frequency using a number of well known techniques. Once the small antenna is impedance matched, the primary characteristics of interest are its radiation efficiency, its operating bandwidth and to a lesser extent, its radiation patterns. The bandwidth of the small antenna is often quantified using the antenna's quality factor (Q) since fundamental lower bounds for Q are defined in terms of the antenna's occupied volume. The lower bound on Q, also known as the Chu-limit, is defined in terms of the spherical volume occupied by the antenna. However, many small antenna designs are constrained to fit within volumes other than a sphere. To address this issue, Gustafsson et al derived lower bounds for antennas of arbitrary shape with a specific focus on cylindrical and planar shaped antennas. In this paper we consider the quality factor of the folded cylindrical helix, an antenna design that effectively utilizes the available cylindrical volume. We compare its Q to the Gustaffson limit as a function of length-to-diameter ratio, while maintaining a fixed value of ka, and show that it’s Q is at or above Gustafsson’s lower bound for cylindrical shaped antennas.

1. BEST, S. R. A comparison of the folded cylindrical helix Q to the Gustafsson limit. In Eucap 2009, Berlin (Germany), March 2009.
2. CHU, L. J. Physical limitations on omni-directional antennas. J. Appl. Phys., 1948, vol. 9, pp. 1163-1175.
3. MCLEAN, J. S. A re-examination of the fundamental limits on the radiation Q of electrically small antennas. IEEE Trans. Antennas Propagat., May 1996, vol. 44, pp. 672-676.
4. BEST, S. R. The radiation properties of electrically small folded spherical helix antennas. IEEE Trans. Antennas Propagat., Apr 2004, vol. 52, no. 4, pp. 953-960.
5. BEST, S. R. Low Q electrically small linear and elliptical polarized spherical dipole antennas. IEEE Trans. Antennas Propagat., Mar 2005, vol. 53, no. 3, pp. 1047-1053.
6. THAL, H. L. New radiation Q limits for spherical wire antennas. IEEE Trans. Antennas Propagat., Oct 2006, vol. 54, no. 10, pp. 2757-2763.
7. GUSTAFSSON, M., SOHL, C., KRISTENSSON, G. Physical Limitations on Antennas of Arbitrary Shape. Lund University Report: LUTEDX/(TEAT-7153)/1-36/(2007), July 2007.
8. GUSTAFSSON, M. Private Communication.
9. YAGHJIAN, A. D., BEST, S. R. Impedance, bandwidth and Q of antennas. IEEE Trans. Antennas and Propagat., Apr 2005, vol. 53, no. 4, pp. 1298-1324.
10. BEST, S. R. A low Q electrically small (TE mode) dipole. IEEE AWPL., vol. 8, pp. 572-575, 2008.

Keywords: Electrically small antennas, quality factor, dipole.

D. Rialet, A. Sharaiha, A. Tarot, X. Castel, C. Delaveaud [references] [full-text] [Download Citations]
Characterization of Antennas on Dielectric and Magnetic Substrates Effective Medium Approximation

This paper presents a study of the effective medium approximation of a monopole antenna printed on either a dielectric or a magnetic substrate. Simple analytical formulas to determine the effective permeability of such an antenna have been proposed and validated. For this type of antenna as μr increases, the effective permeability will reach the value of 2 (maximum) whereas, with the dielectric substrate, the effective permittivity continues to rise when increasing εr. This shows that, for very high permeability values, we will always have a size reduction below 30%.

1. POZAR, D. N. Microstrip Antennas. Proc. IEEE, 1992, vol. 80.
2. BALANIS, C. A. Antenna Theory: Analysis and Design. New York: Wiley, 1997.
3. IKONEN, P. M. T., ROZANOV, K. N., OSIPOV, A. V., ALITALO, P., TRETYAKOV S. A. Magnetodielectric substrate in antenna miniaturization : Potential and limitation. IEEE Tran. on Antennas and Propagation, 2006, vol. 54, no. 11.
4. VOLAKIS, J.L., CHEN, C.C., HALLORAN, J., KOULOURIDIS, S. Miniature VHF/UHF conformal spirals with inductive and ferrite loading. In IEEE Antennas and Propagation Society International Symposium, 9-15 June 2007.
5. PUCEL, D. J., MASSE, R. A. Microstrip propagation on magnetic substrates-Part I & II.. IEEE Tran Microwave Theory Techn., 1972, vol. 20, no. 5.
6. HANSEN, R. C., BURKE, M. Antennas with magneto-dielectrics. Microwave and Optical Technology Letters, 2000, vol. 26.
7. KARKKAINEN, M., TRETYAKOV, S., IKONEN, P. Numerical study of a PIFA with dispersive material fillings. Microwave and Optical Technology Letters, 2005, vol. 45, no. 1.
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9. REINMUT K. HOOFMANN, Handbook of Microwave Integrated Circuit. Chap.13, 1987.
10. ECCOSORB® MF - Lossy, Magnetically Loaded, Machinable Stock, Emerson & Cuming Microwave Products. [Online], Available at: http://www.eccosorb.com

Keywords: Antennas on dielectric and magnetic substrates, effective medium, analytical model.

S. V. Shynu, M. J. Roo-Ons, M. J. Ammann, B. Norton [references] [full-text] [Download Citations]
Dual Band a-Si:H Solar-Slot Antenna for 2.4/5.2GHz WLAN Applications

A simple and compact design of solar-slot antenna for dual band 2.4/5.2GHz wireless local area networks (WLAN) applications is proposed. The design employs amorphous silicon (a-Si:H) solar cells in polyimide substrate with an embedded twin strip slot structure to generate dual resonant frequencies. A T-shaped microstripline feed is used to excite the twin slot in the a-Si:H solar cell. The measured impedance bandwidths for the proposed solar antenna are 25.9% (642 MHz) centered at 2.482 GHz and 8.2% (420 MHz) centered at 5.098 GHz. The measured gain at 2.4 and 5.2 GHz are 3.1 dBi and 2.1 dBi respectively.

1. VACCARO, S., MOSIG, J. R., DE MAAGT, P. Two advanced solar antenna SOLANT designs for satellite and terrestrial communications. IEEE Transactions on Antennas and Propagation, 2000, vol. 51, no. 11, p. 2028 - 2034.
2. HENZE, N., WEITZ, M., HOFMANN, P., BENDEL, C., KIRCHOFF, J., FRUCHTING, H. Investigations on planar antennas with photovoltaic solar cells for mobile communications. In IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC). 2004, vol-1, p. 622- 626.
3. SHYNU, S. V., AMMANN, M. J., NORTON, B. A Quarterwave metal plate solar antenna. IET Electronics Letters, 2008, vol. 44, no. 9, p. 570-571.
4. ROO-ONS, M. J., SHYNU, S. V., AMMANN, M. J., MCCORMACK, S., NORTON, B. Investigation on proximitycoupled microstrip integrated PV antenna. In European Conf Antennas & Propagation, 2007, Edinburgh, TuPA 019.
5. SHYNU, S. V., ROO-ONS, M. J., MCEVOY, P., AMMANN, M. J., MCCORMACK, S., NORTON, B. Integration of microstrip patch antenna with polycrystalline silicon solar cell. IEEE Transactions Antennas & Propag., 2009, AP-57, in press.
6. TANAKA, M., SUZUKI, Y., ARAKI, K., SUSUKI, R. Microstrip antennas with solar cells for microsatellites. IET Electronic Letters, 1996, vol. 31, no. 1, p. 263-266.
7. ZAWADZKI, M., HUANG, J. Integrated RF antenna and solar array for spacecraft application. In Proc. IEEE Phased Array Systems and Technology Conference. Dana Point (CA), May 2000, p. 239–242.
8. VACCARO, S., TORRES, P., MOSIG, J. R., SHAH, A., ZURCHER, J. F, SKRIVERVIK, A. K., DE MAAGT, P., GERLACH, L. Stainless steel slot antenna with integrated solar cells. IET Electronic. Letters, 2000, vol. 36, (25), p.2059–2060.
9. HSIAO, H. M., WU, J. W., WANG, Y. R., LU, J. H., CHANG, S. H. Novel dual-broadband rectangular-slot antenna for 2.4/5-GHz communication. Microwave and Optical Technology Letters, 2005, vol. 46, no. 3, p. 197-200.
10. MORIOKA, T., ARAKI, S., HIRASAWA, K. Slot antenna with parasitic element for dual band operation. IET Electronic Letters, 1997, vol. 33, p. 2093-2094.

Keywords: Solar antenna, slot antenna, amorphous silicon.

J. Abadia, F. Merli, J. Zurcher, J. R. Mosig, A. K. Skrivervik [references] [full-text] [Download Citations]
3D-Spiral Small Antenna Design and Realization for Biomedical Telemetry in the MICS band

This work presents the design and realization procedure of small implantable antenna for biotelemetry applications. The radiator occupies a volume smaller than 3 cm3 (without its biocompatible insulation), is well matched within the Medical Implanted Communications System band and shows an adequate gain (-28.5 dB) while introduced in the appropriate equivalent body medium. The latter is a homogeneous phantom with muscle dielectric properties. A prototype has been manufactured and measurements agree with theoretical predictions. Particular attention is paid to the building requirements such as the presence of glue. Specific Absorption Rate (SAR) distribution has been computed evaluating the maximum power deliverable to the antenna in order to respect the regulated SAR limitation.

1. GREATBATCH, W., HOLMES, C. F. History of implantable devices, IEEE Engineering in Medicine and Biology, 1991, vol. 10, no. 3, p. 38–49.
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6. European Telecommunications Standards Institute. Electromagnetic compatibility and Radio spectrum Matters (ERM); Short Range Devices (SRD); Ultra Low Power Active Medical Implants (ULP-AMI) and Peripherals (ULP-AMI-P) operating in the frequency range 402 MHz to 405 MHz; Part 1 and Part 2, ETSI Std. EN 301 839-1/2 V1.3.1. 2007.
7. Federal Communication Commision. Medical Device Radiocommunication Service (MedRadio), FCC Std., 2009. [Online]. Available at: http://www.fcc.gov/
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9. SOONTORNPIPIT, P., FURSE, C., CHUNG, Y. C. Design of implantable microstrip antenna for communication with medical implants. IEEE Transactions on Microwave Theory and Techniques, 2004, vol. 52, no. 8, p. 1944–1951.
10. KIM, J., RAHMAT-SAMII Y. Implanted antennas inside a human body: simulations, designs, and characterizations. IEEE Transactions on Microwave Theory and Techniques, 2004, vol. 52, no. 8, p. 1934–1943.
11. HALL, P. S., HAO, Y. Antennas and Propagation for Bodycentric Wireless Communications. Norwood: Artech House, 2006.
12. LEE, C. M., YO T. C., LUO, C. H., TU, C. H., JUANG, Y. Z. Compact broadband stacked implantable antenna for biotelemetry with medical devices. Electronics Letters, 2007, vol. 43, no. 12, p. 660–662.
13. KARACOLAK, T., HOOD, A. Z., TOPSAKAL, E. Design of a dual-band implantable antenna and development of skin mimicking gels for continuous glucose monitoring. IEEE Transactions on Microwave Theory and Techniques, 2008, vol. 56, no. 4, p. 1001–1008.
14. KARACOLAK, T., TOPSAKAL, E. Electrical properties of nude rat skin and design of implantable antennas for wireless data telemetry. In Proc. IEEE MTT-S International Microwave Symposium. 2008, p. 907–910.
15. MERLI, F., BOLOMEY, L., MEURVILLE, E., SKRIVERVIK, A. K. Implanted antenna for biomedical applications. In Proc. IEEE Antennas and Propagation Society International Symposium AP-S 2008. 2008, p 1–4.
16. YILMAZ, T., KARACOLAK, T., TOPSAKAL, E. Characterization and testing of a skin mimicking material for implantable antennas operating at ISB band (2.4 GHz-2.48 GHz). IEEE Antennas and Wireless Propagation Letters, 2008, vol. 7, p. 418–420.
17. KARACOLAK, T., COOPER, R., TOPSAKAL, E. Electrical properties of rat skin and design of implantable antennas for medical wireless telemetry. IEEE Transactions on Antennas and Propagation, 2009, vol. 57, no. 9, p. 2806–2812.
18. ABADIA, J., MERLI, F., ZURCHER, J.-F., MOSIG, J. R., SKRIVERVIK, A. K. 3D-spiral small antenna for biomedical transmission operating within the mics band. In Proc. 3rd European Conference on Antennas and Propagation EuCAP 2009. Berlin (Germany) 2009, p. 1845–1849.
19. Zarlink Semiconductors. Integrated Circuit ZL70101. [Online]. Available at: http://www.zarlink.com
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21. SKRIVERVIK, A. K., ZURCHER, J. F., STAUB, O., MOSIG, J. R. PCS antenna design: the challenge of miniaturization. IEEE Antennas and Propagation Magazine, 2001, vol. 43, no. 4, p. 12–27.
22. RAHMAT-SAMII, Y., and KIM, J. Implanted Antennas in Medical Wireless Communications. USA: Morgan & Claypool, 2006.
23. FUJIMOTO, K., HENDERSON, A., HIRASAWA, K., JAMES, J. Small Antennas. 1st Ed. Letchworth: Electronic & Electrical Research Studies Press, 1987.
24. Ansoft Corporation. High Frequency Structure Simulator (HFSS) v11.1 (2009). [Online]. Available at: http://www.ansoft.com/products/hf/hfss/
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26. GABRIEL, C. Compilation of the Dielectric Properties of Body Tissues at RF and Microwave Frequencies, technical report N.AL/OE-TR-. Texas (USA): Brooks Air Force Base, 1996. [Online]. Available at: http://niremf.ifac.cnr.it/tissprop/htmlclie/htmlclie.htm
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28. WAINWRIGHT, P. R. The relationship of temperature rise to specific absorption rate and current in the human leg for exposure to electromagnetic radiation in the high frequency band. Physics in Medicine & Biology, 2003, vol. 48, no. 19, p. 3143–3155.
29. SKRIVERVIK, A. K., ZURCHER, J. F. Recent advances in PCS antenna design and measurement. AUTOMATIKA- Journal for Control, Measurement, Electronics, Computing and Communications, 2002, vol. 43, no. 1-2, p. 55–61.
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Keywords: Electrically Small Antenna (ESA), implantable antenna, Medical Implant Communications Services (MICS), Medical Device Radiocommunication Service (MedRadio), biocompatible antenna.

M. Polivka, D. Vrba [references] [full-text] [Download Citations]
Shielded Micro-Coplanar CRLH TL Zeroth-Order Resonator Antenna: Critical Performance Evaluation

The attention of this paper is focused on the four unit cell zeroth-order resonator antenna (ZORA), manufactured on a shielded micro-coplanar composite right/left-handed (CRLH) transmission line structure. The antenna was designed to achieve a broadside patch-type radiation pattern. The dimensions of the antenna element follow: 15.6 x 9.35 x 3.1 mm (i.e. 0.27 x 0.16 x 0.05 λ0 at the measured zeroth-order resonance f0 = 5.14 GHz) with the shielded plane of the size of 60 x 40 mm (approx. 1.0 x 0.7 λ0). The measured gain and the antenna efficiency are equal to 4.6 dBi and 48 %, respectively. The performance of the proposed ZORA is subject to critical evaluation based on the comparison with the reference quarter-wavelength patch antenna (QWPA) that has the same dimensions. It has been found that ZORA provides comparable or even better parameters to those of QWPA, except of the bandwidth, which is much narrower in case of ZORA. In comparison to QWPA, the main advantage of the proposed ZORA might be then seen in the possibility to produce the entire ZORA structure by means of the integrated microstrip technology with air bridges. In contrary to it, the fabrication of the QWPA requires the use of either the foam substrate or plastic support pins or the application of ridged self-supporting metal plates.

1. SCHUSSLER, M., OERTEL, M., FRITSCHE, C., FREESE, J., JAKOBY, R. Design of periodically L-C loaded patch antennas. In Proc. of 27th ESA Antenna Technology Workshop on Innovative Periodic Antennas. Santiago de Compostela (Spain), 2004.
2. SCHUSSLER, M., FREESE, J., JAKOBY, R. Design of compact planar antennas using LH-transmission lines. In IEEE MTT-S International Microwave Symposium Digest, 2004, p. 209-212.
3. SANADA, A., KIMURA, M., AKAI, I., KUBO, H., CALOZ, C., ITOH, T. A planar zero-th order resonator antenna using lefthanded transmission line. In Proc. of European Microwave Conference. Amsterdam (the Netherlands), 2004.
4. QURESHI, F., ANTONIADES, M. A., ELEFTERIADES, G. V. A compact and low-profile metamaterial ring antenna with vertical polarization. IEEE Antennas and Wireless Propagation Letters, 2005, vol. 4, p. 333-336.
5. PARK, J.-H., RYU, Y.-H., LEE, J.-G., LEE, J.-H. A zeroth-order resonator antenna using epsilon negative meta-structured transmission line. In Proc. of IEEE Antennas and Prop. Symposium. Honolulu (Hawai), 2007.
6. VRBA, D., POLIVKA, M. Radiation efficiency improvement of zeroth-order resonator antenna. Radioengineering, 2009, vol. 18, no. 1, p. 1-8.
7. VRBA, D., POLIVKA, M. Zeroth-order resonator antenna realized on shielded micro-coplanar transmission line. In Proceedings of the 3rd Conference on Antennas and Propagation EuCAP 2009. Berlin (Germany), 2009.
8. IKONEN, P. Electrically small metamaterial-based antennas – have we seen any real practical benefits? In Proceedings of the 3rd Conference on Antennas and Propagation EuCAP 2009. Berlin (Germany), 2009.
9. CALOZ, C. ITOH, T. Electromagnetic Metamaterials: Transmission Line Theory and Microwave Applications. New Jersey: John Wiley & Sons. 2006

Keywords: Antenna efficiency, composite right/left-handed transmission line, patch antenna, radiation efficiency, zeroth-order resonator.

S. Sufyar, C. Delaveaud [references] [full-text] [Download Citations]
A Miniaturization Technique of a Compact Omnidirectional Antenna

This paper discusses a miniaturization technique of a compact omnidirectional antenna. A slot loading technique is applied to a well-known low-profile antenna structure whose radiation characteristics are similar to equivalent monopole ones. An equivalent circuit which models the antenna input impedance including the slot effect is also developed in order to illustrate the antenna working principle. The typical dimensions (width x height) of the obtained antenna are λ0/11 x λ0/75 (λ0 is the free space operating wavelength) which makes it a miniature antenna that can be integrated inside small wireless sensor nodes using narrow band communication systems. Its performances are in accordance with classical fundamental limits, the operating bandwidth and efficiency are significantly reduced with the antenna size reduction.

1. FUJIMOTO, K., HENDERSON, A., HIRASAWA, K., JAMES, J.R. Small Antennas. New York: John Wiley and Sons, Research Studies Press, 1987.
2. HANSEN, R.C. Electrically Small Superdirective and Superconducting Antennas. Hoboken, New Jersey: Wiley, 2006.
3. DELAVEAUD, C., LEVEQUE, P., JECKO, B. Small-sized low-profile antenna to replace monopole antennas. Electronics Letters, 16 Apr 1998, vol. 34, no. 8, p. 716-717.
4. LAU, KL., LI, P., LUK, KM. A monopolar patch antenna with very wide impedance bandwidth. IEEE Transactions on Antennas and Propagation, 2005, vol. 53, no. 3, pp 1004- 1010.
5. ROW, J. S., YEH, S. H., WONG, K. L. A wide-band monopolar plate-patch antenna. IEEE Transactions on Antennas and Propagation., 2002, vol. 50, no. 9, pp. 1328-1330.
6. BOURTOUTIAN, R., DELAVEAUD, C., TOUTAIN, S. Low profile UWB monopole antenna having a sharp band notch function. In European Conference on Antennas and Propagation (EuCAP2006). Nice (France), 2006.
7. ZAID, L., STARAJ, R. Miniature circular GSM wire-patch antenna on small ground plane. Electronics Letters, 14 Feb 2002, vol. 38, no. 4, pp 153-154.
8. JECKO, B., DECROZE, C. The ‘Monopolar Wire Patch Antenna’ concept. In Second European Conference on Antennas and Propagation, EuCAP 2007, 11-16 Nov. 2007, pp 1-5.
9. PASQUET, F., JECKO, B. New developments of the wire-patch antenna for ceramic technology and multifunction applications. In I.E.E.E. Antennas and Propagation Society International Symposium, 8-13 July 2001, vol. 4, pp 62 – 65.
10. WONG, K.L. Compact and Broadband Microstrip Antennas. New York: J. Wiley & Sons, Inc., Wiley Series in Microwave and Optical Engineering.
11. JECKO, F., HAMMOUDI, M. Multi Frequencies Wire Patch Antenna (Antenne fil-plaque Multifrequence). French patent, n° 01 07940, December 2002.
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13. DELAVEAUD, C. New kind of microstrip antenna: the monopolar wire-patch antenna (Etude d’une nouvelle classe d’antenne imprimee a rayonnement monopolaire). PhD dissertation, University of Limoges, Oct. 1996.
14. WOLFF, I., KNOPPIK, N. Rectangular and circular microstrip disk capacitors and resonators. I.E.E.E Trans. on Microwave Theory and Techniques, October 1974, vol. 22, no. 10.
15. WHEELER, H. A. Transmission-line properties of parallel strips separated by a dielectric sheet. I.E.E.E. Trans. on Microwave Theory and Techniques, March 1965, vol. 13, pp. 172-185.
16. LIER, E. Improved formulas for input impedance of coax-fed microstrip patch antennas. I.E.E. Proc., August 1982, pp. 161-164.
17. COMBES, P.F. Micro-ondes, circuits antennes. DUNOD, Tome 2, 1997. passifs, propagation,
18. CHI, C.L., ALEXOPOULOS, N.G. Radiation by a probe through a substrate. IEEE Trans. Antennas and Propagation, September 1986, vol. 34, no. 9, pp. 1080-1091.
19. YAGHJIAN, A. D., BEST, R. Impedance, bandwidth, and Q of antennas. IEEE Trans. Antennas and Propagation, April 2005, vol. 53, no. 4, pp.1298-1324.
20. MCLEAN, J. S. A re-examination of the fundamental limits on the radiation Q of electrically small antennas. IEEE Trans. Antennas and Propagation, May 1996, vol. 44, pp. 672–675.
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Keywords: Omnidirectional radiation, loading, fundamental limits. miniaturization, slot

L. Guo, X. Chen, C. Parini [references] [full-text] [Download Citations]
Study of a Miniaturized Quasi-Self-Complementary UWB Antenna in Frequency and Time Domain

A compact antenna for UWB communication systems has been realized by employing a quasi-selfcomplementary structure together with a triangular notch on microstrip feed line in this paper. The optimal design of this type of antenna can offer an ultra wide return loss bandwidth with reasonable radiation properties. It features a quite small physical dimension of 16 mm x 25 mm, corresponding to an electrically size of 0.24 λ. A good agreement is achieved between the simulated and the measured antenna characteristics. The major parameters that influence the performance of the antenna are investigated numerically to gain an insight into the antenna operation. Time domain performance of the antenna is also examined in order to assess its suitability for impulse radio applications.

1. VIANI, F., LIZZI, L., AZARO, R., MASSA, A. A Miniaturized UWB antenna for wireless dongle devices. IEEE Antennas and Wireless Propagation Letters, 2008, vol. 7, p. 714 - 717.
2. CHEN, Z., SEE, T. Small UWB antennas for wireless USB dongle attached to laptop computer. In IEEE International Workshop on Antenna Technologies: Small and Smart Antennas Metamaterials and Applications (IWAT 2007). Cambridge (UK), 21-23, March 2007.
3. KLEMM, M., TROESTER, G. Textile UWB antennas for wireless body area networks. IEEE Transaction on Antennas and Propagation, 2006, vol. 54, no. 11, p. 3192-3197.
4. CHEN, Z., SEE, T., QING, X. Small printed ultrawideband antenna with reduced ground plane effect. IEEE Transaction on Antennas and Propagation, 2007, vol. 55, no. 2, p. 383-388.
5. ABBOSH, A., BIALKOWSKI, M., JACOB, M., MAZIERSKA, J. Design of a compact ultra wideband antenna. Microw. Opt. Technol. Lett., 2006, vol. 48, p. 1515-1518.
6. XU, P., FUJIMOTO, K., LIN, S. Performance of quasiselfcomplementary antenna using a monopole and a slot. In 2002 IEEE Antennas and Propagation Society Int. Symp. San Antonio (TX, USA), June 2002.
7. KUROKI, F., OHTA, H., YAMAGUCHI, M., SUEMATSU, E. Wall-hanging type of self-complementary spiral patch antenna for indoor reception of digital terrestrial broadcasting. IEEE MTT-S Int. Microw. Symp. Dig., 2006, p. 194-197.
8. WONG, K., WU, T., SU, S., LAI, J. Broadband printed quasi-selfcomplementary antenna for 5.2/5.8 GHz WLAN operation. Microw. Opt. Technol. Lett., 2003, vol. 39, no. 6, p. 495-496.
9. GUO, L., WANG, S., GAO, Y., WANG, Z., CHEN, X., PARINI, C. Study of a printed quasi-self-complementary antenna for ultra wideband systems. IET Electronic Letters, 2008, vol. 44, no. 8, p. 511-512.
10. GUO, L., CHEN, X., PARINI, C. A printed quasi-selfcomplementary antenna for UWB applications. In 2008 IEEE AP-S International Symposium on Antenna and Propagation. San Diego (USA), 5-12, July 2008.
11. MUSHIAKE, Y. Self-complementary antennas. IEEE Antennas Propag. Mag., 1992, vol. 34, no. 6, p. 23-29.
12. MUSHIAKE, Y. A report on Japanese development of antennas: from the Yagi-Uda antenna to self-complementary antennas. IEEE Antennas Propag. Mag., 2004, vol. 46, no. 4, p. 47-60.
13. KRAUS, J. Antennas for All Applications. McGraw-Hill, Inc., 2002.
14. User’s manual. CST-Microwave Studio, 2003.

Keywords: Antenna transient analysis, self-complementary antennas, small antennas, UWB antennas.

B. Ivsic, D. Bonefacic, J. Bartolic [references] [full-text] [Download Citations]
Reconfigurable Pico-cell Antenna Array for Indoor Coverage in GSM 900 Band

This paper proposes a simple antenna array based on three stacked shorted patches aimed to be used as GSM (900 MHz) indoor base station antenna. Three same linearly polarized stacked patches are set in three orthogonal planes in space forming pyramid-like structure. The antenna array can be used for nearly omnidirectional coverage as well as for covering three 120º sectors. The proposed array also offers the possibility of polarization diversity.

1. HUYNH, T., LEE, K. F. Single-layer single-patch wideband microstrip antenna. Electronic Letters, 1995, vol. 31, no. 16, p. 1310-1312.
2. BONEFACIC, D., RAPINAC, B. Small H-shaped shorted patch antennas. Radioengineering, 2008, vol. 17, no. 2, p. 77-82.
3. SKRIVERVIK, A. K., ZURCHER, J.-F., STAUB, O., MOSIG, J.R. PCS antenna design: The challenge of miniaturization. IEEE Antennas and Propagation Magazine, 2001, vol. 43, no. 4, p. 12 to 26.
4. CHAIR, R., LUK, K. M., LEE, K. F. Miniature multilayer shorted patch antenna. Electronics Letters, 2000, vol. 36, no. 1, p. 3-4.
5. OLLIKAINEN, J., FISCHER, M., VAINIKAINEN, P. Thin dual resonant stacked shorted patch antenna for mobile communications. Electronics Letters, 1999, vol. 35, no. 6, p. 437 to 438.
6. The CST website. [Online]. Cited 2009-07-20. Available at: http://www.cst.com/
7. KUMAR, G., RAI, K. P. Broadband Microstrip Antennas. 1st ed. Norwood, USA: Artech House, 2003.
8. CHAIR, R., LUK, K. M., LEE, K. F. Miniature shorted dual-patch antenna. IEE Proceedings Microwaves, Antennas and Propagation, 2000, vol. 147, no. 4, p. 273-276.

Keywords: Antenna size reduction, small antenna, shorted stacked patch, indoor coverage, sector coverage.

D. Manteuffel, M. Arnold, P. Uhlig [references] [full-text] [Download Citations]
Considerations on Configurable Multi-Standard Antennas for Mobile Terminals Realized in LTCC Technology

This paper is an extended version of a paper presented at the EuCAP 2009 conference [1]. We present part of a long term research project that aims on designing a (re-)configurable multi-standard antenna element for 4G (4th Generation) mobile terminals based on LTCC (Low Temperature Co-fired Ceramic) technology. The antenna itself is a coupling element [2] that efficiently excites the chassis of the mobile terminal to radiate as an entire antenna. Coupling is optimized by a reactive tuning circuit. Several of these tuning circuits are realized in a single LTCC component and can be multiplexed to the antenna by a SPnT (Single Pole n Thru) antenna switch integrated into the LTCC component. The coils and capacitor in the LTCC component are configurable on the top-layer of the component. Thus, the component is configurable according to different mobile terminal chassis configurations and multiple bands.

1. MANTEUFFEL, D., ARNOLD, M. Considerations on configurable multi-standard antennas for mobile terminals realized in LTCC technology. In EuCAP2009 – European Conference on Antennas and Propagation. Berlin (Germany), 2009.
2. VILLANEN, J., OLLIKAINEN, J., KIVEKAS, O., VAINIKAINEN, P. Coupling element based mobile terminal antenna structures. IEEE Transactions on Antennas and Propagation, 2006, vol. 54, no. 7, p. 2142 – 2153.
3. MANTEUFFEL, D., BAHR, A., HEBERLING, D., WOLFF, I. Design considerations for integrated mobile phone antennas. In ICAP – International Conference on Antennas and Propagation, Manchester (UK), 2001, p. 252-256.
4. HOLOPAINEN, J., VILLANEN, J., KYRO, M., ICHELN, C., VAINIKAINEN, P. Antenna for handheld DVB terminal. In IEEE International Workshop on Antenna Technology – iWAT 2006, New York (USA), 2006.
5. MANTEUFFEL, D., ARNOLD, M. Considerations for reconfigurable multi-standard antennas for mobile terminals. In IEEE International Workshop on Antenna Technology - IWAT- 2008. Chiba (Japan), 2008.
6. MANTEUFFEL, D., ARNOLD, M., MAKRIS, Y, CHEN, Z. N. Concepts for future multistandard and ultra wideband mobile terminal antennas using multilayer LTCC technology. In IEEE International Workshop on Antenna Technology - IWAT-2009. Santa Monica (USA), 2009.
7. HITTITE Microwave Corporation: HMC253LC4 datasheet. [online] Available at: http://www.hittite.com/content/Documents /data_sheet/hmc253lc4.pdf
8. IMST GmbH. EMPIRETM. http://www.empire.com [online] Available at: http://www.empire.com

Keywords: LTCC, reconfigurable antenna, coupling element, 4G antenna, small terminal antenna.

N. Guan, K. Ito [references] [full-text] [Download Citations]
A Compact Wideband Two-Arm-Antenna for Mobile Phones

A compact film type antenna capable of generating two wide resonant modes for covering the AMPS/GSM bands and the DCS/PCS/UMTS bands for mobile phones is proposed. The antenna consists of two superimposed radiation arms which can support two resonant modes by themselves. The frequency range of a resonant mode generated by one of the arm is arranged to differ a little with the corresponding mode of the other, at the fundamental and higher-order modes. As a result, the bandwidths at both of the resonant modes are significantly enhanced. The antenna has a compact dimension of 5 x 15 x 40 mm3 and covers five bands of AMPS/GSM/DCS/ PCS/UMTS for a VSWR less than 2.5:1. It shows fairly good omnidirectional radiation patterns and high gains over 0 dBi in the azimuthal plane, at all the operating bands.

1. MORISHITA, H. A study on compact antennas and antenna miniaturization for handsets. In Proceeding of 2008 IEEE Int. Workshop on Antenna Technol., Chiba (Japan), 2008, p. 28 - 31.
2. SHIH, Y-L., WANG, B-H., LU, Y-J., CHENG, J-C., CHEN, S-Y., HSU, P. Capacitively-loaded loop antenna for multi-band mobile handsets. In Proceeding of 2008 IEEE Int. Workshop on Antenna Technol., Chiba (Japan), 2008, p. 239 - 242.
3. PARK, G., HWANG, S., BYUN, J., KIM, A. S. The compact quad-band PCB embedded antenna for mobile handsets. In Proceeding of IEEE Int. AP-S Symp., San Diego (USA), 2008.
4. LIN, C-I., WONG, K-L. Printed monopole slot antenna for internal multiband mobile phone antenna. IEEE Trans. on Antennas Propagat., 2007, vol. 55, no. 12, p. 3690 - 3697.
5. TZORTZAKAKIS, M., LANGLEY, R. J. Quad-band internal mobile phone antenna. IEEE Trans. on Antennas Propagat., 2007, vol. 55, no. 7, p. 2097 - 2103.
6. GUAN. N., DELAUNE, D., FURUYA, H., ITO, K. Film antenna for mobile phone applications. In Proceeding of 1st Euro. Wireless Technol. Conf., Amsterdam (The Netherlands), 2008, p. 139 - 142.
7. WHEELER, H. A. The radiansphere around a small antenna. Proc. IRE, 1959, vol. 47, p. 1325 - 1331.

Keywords: Multi-band antenna, compact antenna, mobile phone.

F. Ferrero, A. Diallo, C. Luxey, B. Derat, P. Hamouz, P. Hazdra, J. Rahola [references] [full-text] [Download Citations]
Two-Element PIFA Array Structure for Polarization Diversity in UMTS Mobile Phones

In this paper, we demonstrate the possibility to strongly modify the radiated fields of a UMTS handset by using a phased two-element PIFA array. The structure is composed of a 100x40 mm2 metallic ground plane acting as the Printed Circuit Board (PCB) of the mobile phone. Two UMTS PIFAs are located at the top edge of this PCB. They are fed by a double Quasi-Lumped Coupler able to provide a 360° phase difference between its two outputs. By properly choosing the DC bias of the double QuasiLumped Coupler, we can set a specific phase difference between the two PIFAs. In this way the two-element array is able to radiate different electromagnetic fields. Simulated and measured radiation patterns in the two main planes of the chassis are presented for different phase differences. It is especially revealed that the novel twoantenna structure is able to radiate vertically-polarized electric fields in the azimuthal plane of the phone and horizontally-polarized electric fields in the same plane when changing the phase shift between the antennas from 0° to 180°. Potential applications are polarization-diversity techniques and Specific Absorption Rate reduction for handsets.

1. DIETRICH, C.B., DIETZE, NEALY, K.J.R., STUTZMAN, W.L. Spatial, polarization, and pattern diversity for wireless handheld terminals. IEEE Transactions on Antennas and Propagation, Sept. 2001, vol. 49, no. 9, p. 1271-1281.
2. VILLANEN, J., OLLIKAINEN, J., KIVEKAS, O., VAINIKAINEN, P. Coupling element based mobile terminal antenna structures. IEEE Transactions on Antennas and Propagation, July 2006, vol. 54, no. 7, p. 2142-2153.
3. DIALLO, A., LUXEY, C., LE THUC, P., STARAJ, R., KOSSIAVAS, G. Enhanced diversity antennas for UMTS handsets. In Proc. 1st European Conf. on Antennas & Propagation, EuCAP2006. Nice (France), 6-10 Nov. 2006.
4. DIALLO, A., LUXEY, C., LE THUC, P., STARAJ, R., KOSSIAVAS, G. Enhanced two-antenna structures for UMTS diversity terminals. IET Microwaves, Antennas and Propagation, February 2008, vol. 2, p. 93-101.
5. www.empire.de
6. FERRERO, F., LUXEY, C., STARAJ, R., JACQUEMOD, G., FUSCO, V. Compact quasi-lumped hybrid coupler tunable over a large frequency band. IET Electronics Letters, 13th September 2007, vol. 43, no. 19, p. 1030-1031.
7. FERRERO, F., LUXEY, C., STARAJ, R., JACQUEMOD, G., YEDLIN, M., FUSCO, V. A novel quad-polarization agile patch antenna. IEEE Transactions on Antennas and Propagation, May 2009, vol. 57, no. 5, p. 1562-1566.
8. FERRERO, F., LUXEY, C., STARAJ, R., JACQUEMOD, G., YEDLIN, M., FUSCO, V. Patch antenna with linear polarisation tilt control. IET Electronics Letters, 13th August 2009, vol. 45, no. 17, p. 870-872.
9. FERRERO, F., LUXEY, C., STARAJ, R., JACQUEMOD, G., YEDLIN, M., FUSCO, V. Theory and design of a tunable quasilumped quadrature hybrid coupler, Microwave and Optical Technology Letters, September 2009, vol. 51, no. 9, p. 2219-2222.
10. ANTONINO DAVIU, E. Analysis and design of antennas for wireless communications using modal methods. PhD thesis, Universidad Politecnica de Valencia, Spain, February 2008.
11. HAZDRA, P., HAMOUZ, P. On the modal superposition lying under the MoM matrix equations. Radioengineering, 2008, vol. 17, no. 3, p. 42-46.
12. HARRINGTON, R. F., MAUTZ, J. R. Theory of characteristic modes for conducting bodies. IEEE Transactions on Antennas and Propagation, 1971, vol. 19, no. 5, p. 622-628.
13. DENG, S-M. A study on the special characteristic of near isotropic or ball-like radiation pattern. In Antennas and Propagation Society International Symposium AP-S 2005, Washington (USA), 3-8 July 2005, vol. 2A, p. 284-287.
14. HIRATA, A., MITSUZONO, S., SHIOZAWA, T. Feasibility study of adaptative nulling on handset for 4G mobile communications. IEEE Antennas and Wireless Propagation Letters, 2004, vol. 3, p. 120-122.
15. DERAT, B., LI, Y., BOLOMEY, J.-CH. Limitations for mobile terminals in simultaneous maximization of bandwidth and efficiency in presence of a user. In Proc. 1st European Conf. on Antennas & Propagation, EuCAP2006, Nice (France), 6-10 Nov. 2006.
16. RAHOLA, J., KROGERUS, J. On the polarization state of a mobile terminal. In Proc. ICAP 2003 Conference. Exeter (UK), 31 March-3 April, 2003.

Keywords: Planar Inverted-F Antennas, UMTS Mobile Phones, Polarization Diversity.

H. Arai, J. Ohno [references] [full-text] [Download Citations]
Channel Capacity Enhancement by Pattern Controlled Handset Antenna

This paper presents a radiation pattern controlled antenna for handset terminals to reduce the correlation coefficient between antennas and enhance the channel capacity in MIMO applications. A pair of small inverted-F shaped antennas combined by a phase shifter provides a single port with controlled pattern. To enhance the channel capacity, the phase difference for the IFA array is optimized using the evaluation parameter of reception level, correlation coefficient and mean effective gain of the proposed array geometry. The channel capacity enhancement is verified by assuming Croneker scattering under Nakagami-Rice propagation model.

1. NIRMAL KUMAR DAS, TAKASHI INOUE, TETSUKI TANIGUCHI, YOSHIO KARASAWA An experiment on MIMO system having three orthogonal polarization diversity branches in multipath-rich environment. Proc. IEEE VTC 2004-Fall, Sep. 2004.
2. GETU, B. N., ANDERSEN, J. B. The MIMO cube - a compact MIMO antenna. IEEE Trans. Wireless Comm., May 2005, vol. 4, no. 3, pp. 1136-1141.
3. AOYAMA, H., ARAI, H. Mutual coupling matrix estimation and null forming methods for MBF antennas. Trans. IEICE Japan, vol.E88-B, Jun.2005, no.6, pp.2305-2312.
4. SEUNG-WOOK NAH, ARAI, H. Beam-space MUSIC DOA system using phase shifter. Trans. IEICE Japan, Feb.2007, vol.E90-B, no.2, pp.291-295.
5. www.feko.info
6. KERMOAL, J. P., SCHUMACHER, L., PEDERSEN, K. I., MOGENSEN, P. E., FREDERIKSEN, F. A stochastic MIMO radio channel model with experimental validation. IEEE Journal on Selected Areas in Communications, Aug. 2002, vol.20, no.6, pp.1211-1226.
7. MAKOTO TSRUTA, YOSHIO KARASAWA Simplified estimation method of the largest eigenvalue distribution in Nakagami-Rice MIMO channel. IEICE Trans-B, Sept. 2004, vol. J87-B, no. 9, pp. 1486-1495 (in Japanese)
8. TAKEO OHGANE, TOSHIHIKO NISHIMURA, YASUTAKA OGAWA Applications of space division multiplexing and those performance in a MIMO Channel. Trans. IEICE Japan, May 2005, vol.E88-B, no. 5, pp. 1843-1851.
9. TAGA, T. Analysis for mean effective gain of mobile antennas in land mobile radio environments. IEEE Trans. Vehicular Technology, May 1990, vol. 39, no. 2, pp. 117-131.
10. KARASAWA, Y. Statistical multipath propagation modelling for broadband wireless systems. Trans. IEICE Japan, Mar. 2007, vol.E90-B, no.3, pp.468-484.

Keywords: eywords MIMO, inverted-F shaped antenna, channel capacity, correlation coefficient, MEG.

J. Guterman, A. Moreira, C. Peixeiro, Y. Rahmat-Samii [references] [full-text] [Download Citations]
Antenna-User Interaction in MIMO-Enabled Laptops

The operation of wireless personal communication terminals very close to the user inherently faces the problem of electromagnetic (EM) coupling between the device and the biological tissues. In this paper the effects of the electromagnetic antenna-human interaction is studied for a laptop MIMO antenna system, where four integrated antenna elements can operate simultaneously. Two points of view are considered: antenna performance and EM dosimetry. The first one addresses not only the degradation of the antenna performance but includes also the effect of the human proximity on the antenna characteristics, namely scattering matrix, Total Active Reflection Coefficient (TARC), radiation efficiency and envelope correlation between port signals. The exposure of the human tissues to EM radiation is expressed in terms of Specific Absorption Rate (SAR). These characteristics are evaluated as a function of the array excitation scheme (including phased array approach and MIMO-like signaling) and compared to simple scenarios where all the power is radiated only by one antenna element.

1. JENSEN, M. A., RAHMAT-SAMII, Y. EM interaction of handset antennas and a human in personal communications. In Proceedings of the IEEE, 1995, vol. 42, no. 1, p. 7-17.
2. VAUGHAN, R., ANDERSEN, J. B. Channels, Propagation and Antennas for Mobile Communications. IEE, London, 2003.
3. http://www.cst.com/Content/Products/MWS/Overview.aspx.
4. GUTERMAN, J., RAHMAT-SAMII, Y., MOREIRA, A., PEIXEIRO, C. Quasi-omnidirectional dual-band back-toback E- shaped patch antenna for laptop applications. Electronics Letters, 2006, vol. 42, no. 15, p. 845-847.
5. GUTERMAN, J., RAHMAT-SAMII, Y., MOREIRA, A., PEIXEIRO, C. Radiation pattern of a 2.4/5.2 GHz laptop internal antenna: Near field spherical range measurements and full wave analysis. In Proceedings of the International Workshop on Antenna Technology – iWAT. Cambridge (United Kingdom), 2007.
6. GUTERMAN, J., RAHMAT-SAMII, Y., MOREIRA, A., PEIXEIRO, C. Design of integrated antenna arrays for MIMO enabled laptops. In Proceedings of the IEEE AP-S International Symposium. Honolulu, Hawaii (USA), 2007.
7. BROWNE, D. W., GUTERMAN, J., RAHMAT-SAMII, Y., FITZ, M. P. Performance of integrated antenna arrays for MIMO enabled laptops. In Proceedings of the IEEE AP-S International Symposium. Honolulu, Hawaii (USA), 2007.
8. GUTERMAN, J. Microstrip Antennas for Laptop Terminals. PhD Thesis, Insituto Superior Tecnico, Technical University of Lisbon, July 2008.
9. http://my.smithmicro.com/win/poser/
10. GUTERMAN, J., RAHMAT-SAMII, Y., MOREIRA, A., PEIXEIRO, C. Laptop antenna location Effects on electromagnetic human interaction with E-shaped back-to-back patch. In Proc. of the ICT Mobile Summit. Stockholm (Sweden), 2008.
11. An Internet resource for the calculation of the Dielectric Properties of Body Tissues in the frequency range 10 Hz to 100 GHz, Italian National Research Council. Available at http://niremf.ifac.cnr.it/ tissprop/.
12. MANTRGHI, M., RAHMAT-SAMII, Y. Multiport characteristics of a wide-band cavity backed annular patch antenna for multipolarization operations. IEEE Trans. Antennas and Propagation, 2005, vol. 53, no. 1, p. 466-474.
13. BLANCH, S., ROMEU, J., CORBELLA, I. Exact representation of antenna system diversity performance from input parameter description. Electronics Letters, 2003, vol. 39, no. 9, p. 705-707.
14. CENELEC, European Specification ES 59005, Considerations for the Evaluation of Human Exposure to Electromagnetic Fields (EMFs) from Mobile Telecommunication Equipment (MTE) in the Frequency Range 30 MHz-6 GHz, Ref. n° ES 59005:1998 E, 1998.

Keywords: Laptop antennas, MIMO antenna systems, TARC, SAR, EM dosimetry.

E. Antonino-Daviu, M. Cabedo-Fabres, M. Ferrando-Bataller, M. Gallo [references] [full-text] [Download Citations]
Design of a Multimode MIMO Antenna Using the Theory of Characteristic Modes

In this communication, the design procedure of a multimode Multiple-Input Multiple-Output (MIMO) antenna is presented. The antenna consists of a metallic ring antenna operating with different orthogonal modes, whose performance in a MIMO system is similar to traditional antenna arrays. Thus, a compact MIMO antenna is obtained, which is very suitable for mobile terminals. A modal analysis of the antenna is carried out first by means of the Theory of Characteristic Modes, in order to identify the different radiating modes of the antenna. Then a set of feeding configurations is proposed so as to excite these modes. As the modes must operate in the same frequency band, a loading technique is used in the antenna in order to shift the resonance frequency of the modes to the proper band.

1. SVANTESSON, T. Correlation and channel capacity of MIMO systems employing multimode antennas. IEEE Trans. Vehicular Tech., Nov. 2002, vol. 51, no. 6, pp. 1304-1312.
2. NEIRYNCK, D., WILLIAMS, C., NIX, A., BEACH, M. Exploiting multiple-input multiple-output in the personal sphere. IET Microwaves, Antennas and Propagation, Dec. 2007, vol. 1, no. 6, pp. 1170-1176.
3. WONG, K., CHANG, C., CHEN, B., YANG, S. Three-antenna MIMO system for WLAN operation in a PDA phone. Microwave and Opt. Tech. Letters, July 2006, vol. 48, no. 7, pp. 1238-1242.
4. MIN, K., KIM, D., MOON, Y. Improved MIMO antenna by mutual coupling suppression between elements. In European Conference on Wireless Technology, 3-4 Oct. 2005, pp. 125 –128.
5. KIM, K., LIM, W., YU, J. High isolation internal dual-band planar inverted-F antenna diversity system with band-notched slots for MIMO terminals. In 36th European Microwave Conference, 2006. Sept. 2006, pp. 1414 –1417.
6. DEMMERLE, F., WIESBECK, W. A biconical multibeam antenna for space-division multiple access. IEEE Trans. Antennas Propagat., June 1998, vol. 46, no. 6, pp. 782-787.
7. WALDSCHMIDT, C., WIESBECK, W. Compact wide-band multimode antennas for MIMO and diversity. IEEE Trans. Antennas Propagat., August 2004, vol. 52, no. 8, pp. 1963-1969.
8. GARBACZ, R. J., TURPIN, R. H. A generalized expansion for radiated and scattered fields. IEEE Trans. Antennas Propagat., May 1971, vol. AP-19, pp. 348-358.
9. HARRINGTON, R. F., MAUTZ, J. R. Theory of characteristic modes for conducting bodies. IEEE Trans. Antennas Propagat., AP-19, 5, September 1971, pp. 622-628.
10. CABEDO, M., ANTONINO, E., VALERO, A., FERRANDO, M. The theory of characteristic modes revisited: A contribution to the design of antennas for modern applications. IEEE Antennas and Propag. Magazine, Oct. 2007, vol. 49, no. 5, pp. 52-68.
11. HARRINGTON, R. F., MAUTZ, J. R. Control of radar scattering by reactive loading. IEEE Trans. Antennas Propagat., July 1972, vol. AP-20, no. 4, pp. 446-454.

Keywords: Antenna design, multimode antenna, MIMO, multiple feed, capacitive loading.

R. Serrano, S. Capdevila, A. Aguasca, J. Romeu, L. Jofre [references] [full-text] [Download Citations]
Multiport Multiband Decoupling Optimization for Miniature Antennas

Multiband multiport antennas are increasingly used for wireless communications and sensing miniature devices. The equations governing the multiport multiband antennas are analyzed in this paper with the objective of drawing the design guidelines for low coupling small antennas. Those guidelines have been applied in the design and optimization of a two-port dual band small antenna of size around λ0/13 x λ0/13 at the lowest frequency. Certain coupling conditions are applied to the port loads achieving a coupling reduction of 8 dB when having a simple two-element real load. A reduction of 27 dB can be obtained when having ideal loads composed by a higher number of elements. The antenna geometry is shown together with coupling minimization results.

1. CHU, L. J. Physical limitations of omni-directional antennas. Journal of Applied Physics, 1948, 19, p. 1163-1175.
2. MCLEAN, J. S. The radiative properties of electrically-small antennas. IEEE International Symposium on Electromagnetic Compatibility, p. 320 – 324, Aug. 1994.
3. SERRANO, R., CAPDEVILA, S., DIALLO, A., BLANCH, S. LUXEY, C., LE THUC, P., STARAJ, R. S., ROMEU, J., JOFRE, L. Optimal multiantenna structures for maximum capacity in wireless compact systems. In EUCAP, Edinburgh (UK), Nov 2007.
4. DIALLO, A. LUXEY, C., LE THUC, P., STARAJ, R., KOSSIAVAS, G., FRANZEN, M., KILDAL, P-S., Evaluation of the performances of several four-antenna systems in a reverberation chamber. In Proc International Workshop on Antenna Technology 2007 (iWAT07). Cambridge (UK), 21st-23rd March 2007, p. 166-169.
5. POZAR, D. M. Microwave and RF Design of Wireless Systems. Chapter 11. John Wiley & Sons, Inc., 2001.
6. BEATTY, R. W. Insertion loss concepts. Proceedings of the IEEE. June 1964, vol. 52, p. 663-671.
7. RAHMAT-SAMII, Y., MICHIELSSEN, E. Electromagnetic Optimization by Genetic Algorithms. Ed. Wiley, 1999.
8. SERRANO, R., BLANCH, S. ROMEU, J., JOFRE, L. Evaluation of two novel non-invasive measurement methods for small antennas. In EUCAP, Nice (France), Nov 2006.

Keywords: Multiport multiband antennas, miniature antennas, decoupling, S-parameters, efficiency.

K. Karlsson, J. Carlsson [references] [full-text] [Download Citations]
Circuit Based Optimization of Radiation Characteristics of Single and Multi-Port Antennas

A method for analyzing and optimizing multiport antennas is presented and exemplified. The method was first presented in [1]-[3] and uses data from full wave electromagnetic field (EM) solvers in combination with circuit simulations for efficient calculations of radiation properties of multi-port antennas. The main advantage of the proposed method is that only a few full-wave simulations, which usually are time consuming, are needed when e.g. optimizing the matching circuits for a multi-port antenna. Since embedded element patterns are used, all relevant antenna parameters such as radiation efficiency, diversity gain, available MIMO capacity etc. can efficiently be computed for any port excitation and loading configuration. The methodology has been implemented in software called MPA (Multi-Port Antenna evaluator) which imports port response matrices and embedded element patterns from commercial full-wave codes and post processes the data making it possible to e.g. optimize capacity for a MIMO system. The optimization is done by changing the feeding and matching networks in a circuit simulator that is invoked by the MPA. Finally the software is used on two examples which are analyzed and optimized to illustrate the potential of the method.

1. KARLSSON, K., CARLSSON, J., BELOV, I., KILDAL, P.-S. Software for optimizing multi-port antennas based on precomputed embedded element patterns from commercial codes. In Proceedings of EMB07. Lund (Sweden), October 18–19, 2007.
2. KARLSSON, K., CARLSSON, J., BELOV, I., NILSSON, G., KILDAL, P.-S. Optimization of antenna diversity gain by combining full-wave and circuit simulations. In Proceedings of EuCAP 2007. Edinburgh (UK), Nov. 11–16, 2007.
3. CARLSSON, J., KARLSSON, K. Analysis and optimization of multi-port antennas by using circuit simulation and embedded element patterns from full-wave simulation. In Proceedings of IEEE AP-S International Symposium and URSI Science Meeting. San Diego (USA), July 5-11, 2008.
4. WHEELER, H. A. Fundamental limitations of small antennas, Proc. I.R.E., Dec. 1947, pp. 1479-1484.
5. CHU, L. J. Physical limitations of omni-directional antennas. J. Appl. Phys., 1948, vol. 19, pp. 1163-1175.
6. POZAR, D. M. Microstrip antennas. Proceedings of the IEEE, Jan. 1992, vol. 80, no. 1, pp. 79-91.
7. ROWELL, C. R., MURCH, R. D. A capacitively loaded PIFA for compact mobile telephone handsets. IEEE Trans. Antennas Propagat., May 1997, vol. 45, no. 5, pp. 837-842.
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16. KILDAL, P.-S., ROSENGREN, K. Correlation and capacity of MIMO systems and mutual coupling, radiation efficiency and diversity gain of their antennas: Simulations and measurements in reverberation chamber. IEEE Communications Magazine, Dec. 2004, vol. 42, no. 12, pp. 102-112.
17. ROSENGREN, K., KILDAL, P-S. Radiation efficiency, correlation, diversity gain and capacity of a six monopole antenna array for a MIMO system: theory, simulation and measurement in reverberation chamber. Proceedings of IEE, Microwaves, Optics and Antennas, Feb. 2005, vol. 152, no. 1, pp. 7-16. (See also Erratum published in August 2006).
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25. KILDAL, P.-S., ROSENGREN, K. Electromagnetic analysis of effective and apparent diversity gain of two parallel dipoles. IEEE Antennas and Wireless Propagation Letters, 2003, vol. 2, no. 1, pp. 9-13.
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27. JIN, N., RAHMAT-SAMII, Y. Advances in particle swarm optimization for antenna designs: Real-number, binary, single-objective and multi-objective implementations. IEEE Trans. Antennas Propagat., March 2007, vol. 55, no. 3, part 1, pp. 556 to 567.
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Keywords: Embedded element pattern, optimization, multi-port antenna, antenna efficiency, antenna diversity, impedance matching.

C. Volmer, R. Stephan, M. A. Hein [references] [full-text] [Download Citations]
Evaluation of a Mutually Coupled Diversity Receiver

A quick, reliable, and simple evaluation of mutual coupling effects is essential for the optimization of antenna arrays for small mobile communications devices. In recent papers we have proposed novel figures of merit that quantify the impact on diversity reception in terms of scattering matrix of the array and have confirmed the validity of these formulas by practical diversity measurements. The present paper provides an extended analysis of the measurement data and contrasts the benefits of this method of array characterization with existing approaches.

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13. DIALLO, A., LUXEY, C., LE THUC, P., STARAJ, R., KOSSIAVAS, G. Study and reduction of the mutual coupling between two mobile phone PIFAs operating in the DCS1800 and UMTS bands. IEEE Transactions on Antennas and Propagation, 2006, vol. 54, no. 11, p. 3063–3074.
14. NILSSON, A., BODLUND, P., STJERNMAN, A., JOHANSSON, M., DERNERYD, A. Compensation network for optimizing antenna system for MIMO application. In Proceedings of 2nd European Conference on Antennas and Propagation (EuCAP). Edinburgh (UK), 2007.
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17. KILDAL, P.-S. ROSENGREN, K. Correlation and capacity of MIMO systems and mutual coupling, radiation efficiency, and diversity gain of their antennas: Simulations and measurements in a reverberation chamber. IEEE Commununication Magazine, 2004, vol. 42, no. 12, p. 104–112.
18. LAU, B. K., BACH ANDERSEN, J., KRISTENSSON, G., MOLISCH, A. F. Impact of matching network on bandwidth of compact antenna arrays. IEEE Transactions on Antennas and Propagation, 2009, vol. 54, no. 11, p. 3225–3238.
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22. DIETRICH, JR., C. B., DIETZE, K., NEALY, J. R., STUTZMAN, W. L. Spatial, polarization, and pattern diversity for wireless handheld terminals. IEEE Transactions on Antennas and Propagation, 2001, vol. 49, no. 9, p. 1271–1281.
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Keywords: Mutual coupling, antenna diversity, decoupling and matching network.

C. Orlenius, M. Andersson [references] [full-text] [Download Citations]
Repeatable Performance Measurements of MIMO Systems in Connected Reverberation Chambers with Controlled Keyhole Effect

A straightforward, fast, and repeatable procedure for measuring the system performance of the antennas in a MIMO system is presented. Due to the use of two connected reverberation chambers, the so called keyhole effect is observed and can be controlled. The method is possible to use for performance measurements of complete MIMO systems, and the present paper lays out the basics for making this possible.

1. ROSENGREN, K., KILDAL, P.-S., CARLSSON, C., CARLSSON, J. Characterization of antennas for mobile and wireless terminals in reverberation chambers: Improved accuracy by platform stirring. Microwave and Optical Technology Letters, 2001, vol. 30, no 20, p. 391-397.
2. KILDAL, P-S., CARLSSON, C. Detection of a polarization imbalance in reverberation chambers and how to remove it by polarization stirring when measuring antenna efficiencies. Microwave and Optical Technology Letters, 2002, vol. 34, p. 145 to 149.
3. KILDAL, P.-S. Overview of 6 years R&D on characterizing wireless devices in Rayleigh fading using reverberation chambers. In International Workshop on Antenna Technology (iWAT07). Cambridge (UK), 2007, p. 162-165.
4. CARLSSON, C. Characterization of Mode-Stirred Chamber and its Setups for Antenna Measurements. Master Thesis, Department of Electromagnetics, Chalmers University of Technology, Gothenburg, Sweden, 2001.
5. WOLFGANG, A., CARLSSON, J., ORLENIUS, C., KILDAL, P.- S. Improved procedure for measuring efficiency of small antennas in reverberation chambers. In Proc. of the IEEE Int. Symposium on Antennas and Propagation, Columbus (Ohio), 2003.
6. KILDAL, P.-S., ROSENGREN, K., BYUN, J., LEE, J. Definition of effective diversity gain and how to measure it in a reverberation chamber. Microwave and Optical Technology Letters, 2002, vol. 34, p. 56-59.
7. KILDAL, P.-S., ROSENGREN, K. Correlation and capacity of MIMO systems and mutual coupling, radiation efficiency and diversity gain of their antennas: Simulations and measurements in reverberation chamber. IEEE Communications Magazine, 2004, vol. 42, no. 12, p. 102-112.
8. ROSENGREN, K., KILDAL, P.-S. Radiation efficiency, correlation, diversity gain, and capacity of a six monopole antenna array for a MIMO system: Theory, simulation and measurement in reverberation chamber. Proceedings IEE, Microwave Antennas Propagation, 2006, vol. 152, no. 1, p. 7-16. See also Erratum published in August 2006.
9. ANDERSSON, M., ORLENIUS, C., FRANZEN, M. Very fast measurements of effective polarization diversity gain in a reverberation chamber. In Proceedings of European Conference on Antennas and Propagation (EuCAP), 2007, Edinburgh, UK.
10. KILDAL, P.-S, CARLSSON, C. TCP of 20 Mobile Phones Measured in Reverberation Chamber: Procedure, Results, Uncertainty and Validation. Available from Bluetest AB, Gothenburg, Sweden, 2002.
11. ORLENIUS, C., KILDAL, P.-S., POILASNE, G. Measurements of total isotropic sensitivity and average fading sensitivity of CDMA phones in reverberation chamber. In Proceedings of the IEEE International Symposium on Antennas and Propagation, Washington DC, 2005.
12. KOSTAS, J. G., BOVERIE, B. Statistical model for mode-stirred chamber. IEEE Transactions on Electromagnetic Compatibility, 1991, vol. 33, no. 4, p. 366-370.
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14. ANDERSSON, M., WOLFGANG, A., ORLENIUS, C., CARLSSON, J. Measuring Performance of 3GPP LTE Terminals and Small Base Stations in Reverberation Chambers. Chapter 12 of Long Term Evolution: 3GPP LTE Radio and Cellular Technology. FURHT, B., AHSON, S. (ed.), CRC Press, 2009.
15. OLANO, N., ORLENIUS, C., ISHIMIYA, K., YING, Z. WLAN MIMO throughput test in reverberation chamber. In Proceedings of the IEEE International Symposium on Antennas and Propagation, San Diego, CA, 2008.
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Keywords: Reverberation chamber, Multiple-Input-Multiple-Output, MIMO, antenna characterization.

L. J. Foged, A. Scannavini [references] [full-text] [Download Citations]
Efficient Testing of Wireless Devices from 800 MHz to 18 GHz

Small antennas and other modern communication applications are using increasingly higher frequencies while demanding shorter development time and very rapid testing cycles. A fast and accurate way to exhaustively determine antenna performance and/or investigate device malfunction is based on spherical near field measurement techniques combined with probe array technology.
This paper describes the innovative design aspects of the StarLab portable antenna measurement system and present results from the validation campaigns including both passive and active measurements. The use of integrated diagnostic and analysis software modules for efficient antenna design and testing is also presented.

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2. FOGED, L. J., ESTRADA, J., IVERSEN, P. O. pherical near field testing of small antennas from 800 MHz to 18 GHz. In IEEE International Symposium on Antennas and Propagation. Honolusu (USA), 2007.
3. ROBIC, N., DUCHESNE, L., GARREAU, P., GANDOIS, A., IVERSEN, P. O., FOGED, L. J. A compact spherical near-field system for antenna testing from 800 MHz to 18 GHz. In The first European Conference on Antennas and Propagation EuCap 2006. Nice (France), 2006.
4. DUCHESNE, L., GARREAU, P., ROBIC, N., GANDOIS, A., IVERSEN, P. O., BARONE, G. Compact multi-probe antenna test station for rapid testing of antennas and wireless terminals. In 26th Annual Meeting and Symposium of Antenna Measurement Techniques Association AMTA 2004. Georgia (USA), 2004.
5. IVERSEN, P. O., GARREAU, P., ENGLUND, K., PASALIC, E., EDVARDSSON, O., ENGBLOM, G. Real time spherical near field antenna test range for wireless applications. In 21st Annual Meeting and Symposium of Antenna Measurement Techniques Association AMTA 1999. Monterey Bay (USA), 1999.
6. FOGED, L. J., MIOC, F., IVERSEN, P. O., NOREN, P. Holographic back-projection for measured low and medium gain antennas in a spherical near field range. In AMTA Europe Symposium 2006 Proceedings. Munich (Germany), 2006.
7. FOGED, L. J., MIOC, F., BENCIVENGA, B., DI GIAMPAOLO, E., SABBADINI, M. High frequency numerical modeling using measured sources. In IEEE AP-S International Symposium. Albuquerque (USA), 2006.
8. ANSI/IEEE. IEEE Standard Test Procedures for Antennas, ANSI/IEEE Std 149-1979 (R2003). 2003.
9. HANSEN, J. E. Spherical Near-Field Antenna Measurements. London: Peter Peregrinus, 1988.
10. GIACOMINI, A., BENCIVENGA, B., DUCHESNE, L., FOGED, L. J. Determination of high accuracy performance data for dipole reference antennas. In AMTA Europe Symposium 2006 Proceedings. Munich (Germany), 2006.
11. FOGED, L. J., GARREAU, P., BREINBJERG, O., PIVNENKO, S., CASTAÑER, M., ZACKRISSON, J. Facility comparison and evaluation using dual ridge horn. In 27th Annual Meeting and Symposium of Antenna Measurement Techniques Association AMTA 2005. Newport (USA), 2005.
12. FOGED, L. J., GIACOMINI, A., MORBIDINI, R., SHETH, V. R., SHARMA, S. B., MALAVIYA, R. K., SANADIYA, H. C. Circular polarised wide-band field probes. In 30th Annual Meeting and Symposium of Antenna Measurement Techniques Association AMTA 2008. Boston (USA), 2008.
13. FOGED, L. J., GIACOMINI, A., MORBIDINI, R., SCIALACQUA, L. High accuracy field probes in circular polarization. In IEEE, APS Symposium. Charleston (USA), 2009.

Keywords: Antenna Measurements, Spherical Near Field, Probe Array, Small Antennas, OTA (over-the-air) measurements, TRP (Total Radiated Power), TIS (Total Radiated Sensitivity), CTIA (Cellular Telecommunications and Internet Association), 3GPP (3G Partner Part

K. B. Baltzis [references] [full-text] [Download Citations]
Impact of Finger Placement on the Correlation Properties of Rake Combined Signals

3G mobile devices and base stations employ rake receivers. An important issue in the design of such receivers is finger allocation. This paper explores the relationship between finger placement and the correlation properties of rake combined signals. The dependence of correlation coefficients on system parameters such as the multipath characteristics of the propagation channel, the number of users, the processing gain and the thermal noise power is also discussed. Several conclusions useful in the analysis and design of rake receivers are drawn. A low complexity finger placement algorithm is finally suggested. In the proposed receiver, finger allocation is based on the correlation properties of the desired signal component only. The receiver performs close to complex structures in the literature.

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4. SABERINIA, E., TANG, J., TEWFIK, A. H., PARHI, K. K. Pulsed-OFDM modulation for ultrawideband communications. IEEE Transactions on Vehicular Technology, 2009, vol. 58, no. 2, p. 720-726.
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15. CHOI, S., ALOUINI, M. –S., QARAQE, K. A. Finger management schemes for RAKE receivers with a minimum call drop criterion. IEEE Transactions on Communications, 2009, vol. 57, no. 2, p. 348 352.
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18. OLIVEIRA, L. D., CIRIACO, F., ABRÃO, T., JESZENSKY, P. J. E. Local search multiuser detection. AEU International Journal of Electronics and Communications, 2009, vol. 63, no. 4, p. 259-270.
19. KADDOUM, G., ROVIRAS, D., CHARGÈ, P., FOURNIER-PRUNARET, D. Robust synchronization for asynchronous multi-user chaos-based DS-CDMA. Signal Processing, 2009, vol. 89, no. 5, p. 807-818.
20. LI, X. J., CHONG, P. H. J. Performance investigation of CDMA/PRMA with imperfect power control in TDD cellular systems. Wireless Personal Communications, 2009, 12 pages. DOI: 10.1007/s11277-009-9729-9.
21. DONG, X., BEAULIEU, N. C. Optimal maximal ratio-combining with correlated diversity. IEEE Communication Letters, 2002, vol. 6, no. 1, p. 22-24.
22. BRANKE, J., DEB, K., MIETTINEN, K., SLOWINSKI, R. (Eds.) Multiobjective Optimization: Interactive and Evolutionary Approaches. Berlin: Springer-Verlag: 2008.
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Keywords: Rake receiver, correlation, spread spectrum, mobile communications, multi-objective optimization

P. Kejik, S. Hanus [references] [full-text] [Download Citations]
Enhanced Receivers for Interference Cancellation in 3G Systems

Interference cancellation and multiuser detection in CDMA systems are still actual research topics. These techniques enable us to deal with interference and to increase system capacity. In this paper, a so-called Generalized RAKE receiver, an Uplink generalized multiuser detection and a Blind adaptive multiuser detection are described. These algorithms are compared with conventional receivers and their properties are verified via simulations. The results imply that some of these algorithms are able to overcome the performance of the conventional receivers.

1. BOTTOMLEY, G., OTTOSSON, T., WANG, Y-P. A generalized RAKE receiver for interference suppression. IEEE Journal on Selected Areas in Communications, Aug. 2000, vol. 18, no. 8.
2. SUNDARARAJAN, J., MAHESHWARI, V., KOILPILLAI, R. Throughput enhancement in WCDMA using the generalized rake receiver. IETE Journal of Research, January 2005.
3. CAI, L., XU, Y., ZHANG, H., SONG, W. Performance of group ordered successive interference cancellation for multiuser detection in GSTBC SFH/MC DS-CDMA system. Wireless Communications and Mobile Computing, June 2006, vol. 6, pp. 475-482, DOI: 10.1002/wcm.290.
4. BENTRCIA, A., ZERGUINE, A., SHEIKH, A. Low-complexity linear group-SIC detectors. Wireless Communications and Mobile Computing, June 2007, vol. 7, pp. 595-604, DOI: 10.1002/wcm.374.
5. ZHENG, Z., YANG, Z., ZHU, Y., PAN, C. Channel estimation and interference suppression for uplink CDMA mobile communication systems. Wireless Communications and Mobile Computing, August 2004, vol. 4, pp. 483-489, DOI: 10.1002/wcm.191.
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12. HONIG, M., MADHOW, U., VERDU, S. Blind adaptive multiuser detection. IEEE Transactions on Information Theory, July 1995, vol. 41, no. 4.
13. KEJIK, P., HANUS S. Interference cancellation in 3G systems. In Proceedings of the Sixteenth International Electrotechnical and Computer Science Conference ERK 2007 (ISSN 1581-4572). Portoroz (Slovenia): Slovenia Section IEEE, Ljubljana University, 2007, p. 257-260.

Keywords: Interference cancellation, multiuser detection, CDMA, G-RAKE.

P. Kadlec, P. Kejik, Z. Raida [references] [full-text] [Download Citations]
Comparison of Pilot Symbol Embedded Channel Estimation Algorithms

In the paper, algorithms of the pilot symbol embedded channel estimation are compared. Attention is turned to the Least Square (LS) channel estimation and the Sliding Correlator (SC) algorithm. Both algorithms are implemented in Matlab to estimate the Channel Impulse Response (CIR) of a channel exhibiting multi-path propagation. Algorithms are compared from the viewpoint of computational demands, influence of the Additive White Gaussian Noise (AWGN), an embedded pilot symbol and a computed CIR over the estimation error.

1. HOLMA, H., TOSKALA, A. WCDMA for UMTS, 3/E. Chichester: J. Wiley and Sons, 2004.
2. EKMAN, T. Prediction of Mobile Radio Channels. Dissertation thesis. Uppsala: Uppsala University, Signals and Systems, 2002.
3. MARQUES, P., GAMEIRO, L., FERNANDES, J. Channel estimation method with improved performance for the UMTS-TDD mode. Wireless Personal Communications, 2006, no. 37, p. 1-21.
4. PROAKIS, J. Wiley Encyclopedia of Telecommunications. New Jersey: J. Wiley and Sons, 2003.
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6. SENGUPTA, C. Algorithms and Architectures for Channel in Wireless CDMA Communication Systems. Dissertation thesis. Houston: Rice University, Electrical and Computer Engineering, 1998.
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9. OZEN, S., ZOLTOWSKI, M. D., FIMOFF, M. A novel channel estimation method: blending least-squares and correlation based methods. In IEEE Int. Conf. on Acoustics, Speech and Signal Processing (ICASSP). Orlando (FL), 2002, vol. 3, pp. 2281-2284.

Keywords: Channel estimation, Least Squares, Sliding Correlator, AWGN channel, Hadamard function.

P. Lafata, J. Vodrazka [references] [full-text] [Download Citations]
Modeling of Transmission Functions and Crosstalk in Metallic Cables for Implementation of MIMO Concept

The new promising wireless networks based on multi-carrier modulations (MCM) and multiple-input multiple-output concept (MIMO) will soon offer high-speed digital connections. Their access points are mostly connected by fixed metallic lines to core data and telecommunication networks. That is why it will also be necessary to increase the transmission speed and overall performance of these fixed access networks adequately in order to meet the expected requirements of wireless connections. It would be possible to use VDSL2 digital subscriber lines and implement MIMO concept into the existing metallic networks for this purpose, but before that it will be necessary to solve several problems first. The transmission capacity of present VDSL2 digital lines is limited mainly by crosstalk occurring in metallic cables. This paper describes a new method for modeling of transmission functions and crosstalk in multi-pair and multi-quad metallic cables including its mathematical implementation, and it also gives an example of results obtained so far. The presented model is based on statistical evaluations of measured values, generation of pseudo-random components of frequency response and subsequent filtration process.

1. VODRAZKA, J., HUBENY, T. Wired core network for local and premises wireless networks. Personal Wireless Communications. New York: Springer, 2007, p. 332-340.
2. BRADY, M. H., CIOFFI, J. M. The worst-case interference in DSL systems employing dynamic spectrum management. Journal on Applied Signal Processing, 2006, vol. 2006, p. 1-11.
3. VODRAZKA, J. Multi-carrier modulation and MIMO principle application on subscriber lines. Radioengineering, 2007, Vol. 16, No. 4, p. 33-37.
4. LAFATA, P., VODRAZKA, J. Simulations and statistical evaluations of FEXT crosstalk in xDSL systems using metallic cable constructional arrangement. In TSP - 31st International Conference Telecommunications and Signal Processing. Budapest (Hungary), 2008.
5. LAFATA, P., VODRAZKA, J. Practical application of FEXT models for VDMT modulation. In Proceedings of VIIIth Conference KTTO 2008. Ostrava (Czechia), 2008, p. 85-88.
6. CENDRILLON, R., GINIS, G., VAN DEN BOGAERT, E., MOONEN, M. A near-optimal linear crosstalk canceller for upstream VDSL. IEEE Transactions on Signal Processing, 2006, vol. 54, no. 8, p. 3136-3146.
7. CENDRILLON, R., GINIS, G., MOONEN, M., ACKER, K. Partial crosstalk precompensation in downstream VDSL. Signal Processing, 2004, vol. 84, no. 11, p. 2005-2019.
8. VODRAZKA, J., LAFATA, P. Transmission environment modeling for VDMT system simulation. In Proceedings CD-ROM of Digital Technologies 2007. Zilina (Slovakia), 2007.
9. STARR, T., CIOFFI J. M., SILVERMAN, P. J. Understanding Digital Subscriber Line Technology. Upper Saddle River (USA): Prentice Hall PTR, 1999.

Keywords: Multi-carrier modulation, multiple-input multiple-output, vectored DMT modulation, crosstalk, modeling.

L. Liu, C. Tao, J. Qiu, X. Qi [references] [full-text] [Download Citations]
A Novel Comb-Pilot Transform Domain Frequency Diversity Channel Estimation for OFDM System

Due to implementation complexity, the transform domain channel estimation based on training symbols or comb-type pilots has been paid more attention because of its efficient algorithm FFT/IFFT. However, in a comb-type OFDM system, the length of the channel impulse response is much smaller than the pilot number. In this case, the comb-pilot transform domain channel estimation only works as interpolation like the Least Squares (LS) algorithm, but loses the noise suppression function. In this paper, we propose a novel frequency diversity channel estimation method via grouped pilots combining. With this estimator, not only the channel frequency response on non-pilot subcarriers can be interpolated, but also the noise can be better suppressed. Moreover, it does not need prior statistical characteristics of the wireless channel.

1. PRASAD, R. OFDM for Wireless Communications Systems. Boston: Artech House, 2004.
2. VAN NEE, R., PRASAD, R. OFDM for Wireless Multimedia Communications. Boston: Artech House, 2000.
3. LI, Y. Pilot-symbol-aided channel estimation for OFDM in wireless systems.IEEE Transactions on Vehicular Technology, 2000, vol. 49, no. 4, p. 1207-1215.
4. MORELLI, M., MENGALI, U. A comparison of pilot-aided channel estimation methods for OFDM systems. IEEE Transactions on Signal Processing, 2001, vol. 49, no. 12, p. 3065-3073.
5. ATHAUDAGE, R. N. C., JAYALATH, A. D. S. Low-complexity channel estimation for wireless OFDM systems. In Proceedings of IEEE International Symposium on Personal, Indoor and Mobile Radio Communincations, vol.1. Beijing (China), 2003, p. 521-25.
6. KANG, S. G., HA, Y. M., JOO, E. K. A comparative investigation on channel estimation algorithms for OFDM in mobile communications. IEEE Transactions on Broadcasting, 2003, vol. 49, no. 2, p. 142-149.
7. EDFORS, O. et al. Analysis of DFT-Based channel estimators for OFDM. Personal Wireless Communications, 2000, vol. 12, no. 1, p. 55-70.
8. ZHAO, Y., HUANG, A. A novel channel estimation method for OFDM mobile communication systems based on pilot signals and transform-domain processing. In Proceedings of 47th IEEE Vehicular Technology Conference, vol. 3. Phoenix (USA), 1997, p. 2089-2093.
9. GARCIA, M. J. F. G., PAEZ-BORRALLO, J. M., ZAZO, S. DFT-based channel estimation in 2D-pilot-symbol-aided OFDM wireless systems. In Proceedings of 53rd IEEE Vehicular Technology Conference, vol. 2. Rhodes (Greece), 2001, p. 810-814.
10. KWAK, K. et al. A new DFT-based channel estimation approach for OFDM with virtual subcarriers by leakage estimation. IEEE Transactions on Wireless Communications, 2008, vol. 7, no.6, p. 2004-2008.
11. VAN DE BEEK, J. J. et al. On channel estimation in OFDM systems. In Proceedings of 45th IEEE Vehicular Technology Conference, vol. 2. Chicago (USA), 1995, p. 815-819.
12. OZDEMIR, M. K., ARSSLAN, H. Channel estimation for wireless OFDM systems. IEEE Communications Surveys & Tutorials, 2007.
13. ITU-R M.1225: Guideline for Evolution of Radio Transmission Technologies for IMT-2000. Geneva: International Telecomunication Union, 2000.

Keywords: Channel estimation, transform domain, orthogonal frequency division multiplexing (OFDM), noise suppression.

V. Wieser, V. Psenak [references] [full-text] [Download Citations]
Performance of Predictor Based Link Adaptation Algorithms

The presented paper deals with the link adaptation algorithms in mobile radio access networks based on Wideband Code Division Multiple Access (WCDMA). The mobile radio channel has a significant impact on the transmitted signal between User Equipment (UE) and Base Station (BS). The character of environment (e.g. number of received reflections) and increasing UE velocity cause unfavorable signal fadings, which have a major impact on the received signal. Due to this fact and the principle of WCDMA, fast power adaptation is essential for mobile radio access networks based on WCDMA. The prediction of mobile radio channel near-future state is one of the possible approaches how to span its unfavorable state. According to this assumption, we have improved the basic link adaptation algorithm (used to control properties of transmitter) to predictor based link adaptation algorithm. This contribution comprises the performance of basic link adaptation algorithm and predictor based algorithms, which support both variable (multi-bit) and fixed (singlebit) power steps to modify transmitter output power level. The link adaptation algorithms were simulated under various average UE velocities in urban environment. New algorithms were designed to increase the efficiency of data transmission in uplink direction.

1. SCHWARTZ, L., TRSTENSKY, D., CEPCIANSKY, G. Next network generation. Advances in Electrical and Electronic Engineering, May 2006, no. 3, p. 381-385, ISSN 1336-1376.
2. DOBOS, L., JUHAR, J., GAMCOVA, M. Some aspect of UMTS and B-ISDN/ATM integration. In International Symposium on Telemedicine and Tele-Education in Practice (ISTEP 2000). Kosice (Slovak Republic), 22-24 March, 2000. ISBN 80-88964-38-5.
3. CASTRO, P. J. The UMTS Network and Radio Access Technology – Air Interface Techniques for Mobile Systems. Wiley, 2001, ISBN 0 471 81375 3.
4. 3rd Generation Partnership Project (3GPP), Technical Specification (TS) 25.213 V6.2.0 (2005-03). Spreading and modulation (FDD).
5. 3rd Generation Partnership Project (3GPP), Technical Specification (TS) 25.212 V6.4.0 (2005-03). Multiplexing and channel coding (FDD).
6. HOLMA, H., TOSKALA, A.: HSDPA / HSUPA for UMTS. Wiley, 2001. ISBN: 0-470-01888-4
7. WIESER, V., PSENAK, V. BER and SIR based hybrid link algorithms performance in mobile radio channel. Radioengineering, 2005, no.4, vol. 14, p. 81-86, ISSN 1210-2512.
8. EKMAN, T. Prediction of Mobile Radio Channels. PhD thesis, Uppsala University, Sweden, 2001.
9. EKMAN, T. Prediction of Mobile Radio Channels – Modelling and Design. Dissertation for the degree of Doctor of Philosophy in Signal Processing at Uppsala University, Sweden, 2002, ISBN 91-506-1625-0.
10. WIESER,V., PSENAK,V. Performance of hybrid link adaptation algorithm with prediction of mobile radio channel state. In TPS 2007, 30th International Conference on Telecommunications and Signal Processing. 2007, Brno (Czech Republic), pp. 32-35, ISBN 978-80-214-3445-5.
11. FALAHATI, S., STERNAD, M. Maximizing Throughput with Adaptive M-QAM based on Imperfect Channel Predictions. Signals and Systems, Uppsala University, 2004. [Online] Available at: http://citeseerx.ist.psu.edu
12. ETSI TR 101 112 V3.2.0. (1998-04). Selection Procedures for the Choice of Radio Transmission Technologies of the UTMS.
13. HOLMA, H., TOSKALA, A. HSDPA/HSUPA for UMTS: High Speed Radio Access for Mobile Communications. John Wiley & Sons LTD, England, 2006, ISBN: 0-470-01884-4.
14. EKMAN, T., STERNAD, M., AHLEN, A. Unbiased Power Prediction of Rayleigh Fading Channels. Signals and Systems, Uppsala University, Sweden, 2002. [Online] Available at: http://citeseerx.ist.psu.edu
15. OIEN, G. E., HOLM, H., HOLE, K. J. Impact of Channel Prediction on Adaptive Coded Modulation Performance in Rayleigh Fading. Department of Electronics and Telecommunications, Norwegian University of Science and Technology, Trondheim, Norway, 2004. [Online] Available at: http://citeseerx.ist.psu.edu

Keywords: WCDMA based mobile radio access networks, link adaptation, prediction methods, mobile radio channel.

H. Yang, X. Sun, G. Sun [references] [full-text] [Download Citations]
A High-Capacity Image Data Hiding Scheme Using Adaptive LSB Substitution

Many existing steganographic methods hide more secret data into edged areas than smooth areas in the host image, which does not differentiate textures from edges and causes serious degradation in actual edge areas. To avoid abrupt changes in image edge areas, as well as to achieve better quality of the stego-image, a novel image data hiding technique by adaptive Least Significant Bits (LSBs) substitution is proposed in this paper. The scheme exploits the brightness, edges, and texture masking of the host image to estimate the number k of LSBs for data hiding. Pixels in the noise non-sensitive regions are embedded by a k-bit LSB substitution with a lager value of k than that of the pixels in noise sensitive regions. Moreover, an optimal pixel adjustment process is used to enhance stego-image visual quality obtained by simple LSB substitution method. To ensure that the adaptive number k of LSBs remains unchanged after pixel modification, the LSBs number is computed by the high-order bits rather than all the bits of the image pixel value. The theoretical analyses and experiment results show that the proposed method achieves higher embedding capacity and better stegoimage quality compared with some existing LSB methods.

1. BENDER, W., GRUHL, D., MORIMOTO, N., AIGUO LU Techniques for data hiding. IBM Systems Journal, 1996, vol. 35, no. 3-4, p. 313-336.
2. SHU-KEI YIP, OSCAR C. AU, HOI-MING WONG, CHI-WANG HO Block-based lossless data hiding in delta domain. In Proc. ICME 2006, Toronto, Ontario (Canada), 2006, p. 857-860.
3. CHING-YU YANG Based upon RBTC and LSB substitution to hide data. In Proc. First International Conference on Innovative Computing, Information and Control (ICICIC’06), Beijing (China), Aug. 30 - Sept. 1, 2006, vol. 1, p. 476-479.
4. CHIN-CHEN CHANG, CHIA-CHEN LIN, CHUN-SEN TSENG, WEI-LIANG TAI Reversible hiding in DCT-based compressed images. Information Sciences, 2007, vol. 177, no. 13, p. 2768-2786.
5. YANG YOU, YU PING, XU JIANGFENG An improved LSB algorithm based on multi-transformation. In Proc. 2008 International Symposium on Information Science and Engineering (ISISE’08). Shanghai (China), Dec. 20-22, 2008, vol. 1, p. 487-491.
6. THIEN, C. C., LIN, J. C. A simple and high-hiding capacity method for hiding digit-by-digit data in images based on modulus function. Pattern Recognition, 2003, vol. 36, p. 2875-2881.
7. CHIN-CHEN CHANG, MIN-HUI LIN, YU-CHEN HU A fast and secure image hiding scheme based on LSB substitution. International Journal of Pattern Recognition and Artificial Intelligence, 2002, vol. 16, no. 4, p. 399-416.
8. KER, A. Improved detection of LSB steganography in grayscale images. In Proc. 6th International Workshop. Toronto (Canada), May 23-25, 2004, Springer LNCS, vol. 3200, p. 97–115.
9. SHARP, T. An implementation of key-based digital signal steganography. In Proc. 4th International Information Hiding Workshop. Pittsburgh (USA), April 25-27, 2001, Springer LNCS, vol. 2137, p. 13–26.
10. JARNO MIELIKAINEN LSB matching revisited. IEEE Signal Processing Letters, 2006, vol. 13, no. 5, p. 285-287.
11. XIAOLONG LI, BIN YANG, DAOFANG CHENG, TIEYONG ZENG A generalization of LSB matching. IEEE Signal Processing Letters, 2009, vol. 16, no. 2, p. 69-72.
12. JEN-CHANG LIU, MING-HONG SHIH Generalizations of pixel-value differencing steganography for data hiding in images. Fundamenta Informaticae, 2008, vol. 83, no. 3, p. 319-335.
13. RAN-ZAN WANG, CHI-FANG LIN, JA-CHEN LIN Hiding data in images by optimal moderately significant bit replacement. IET Electronics Letters, 2000, vol. 36, no. 25, p. 2069-2070.
14. RAN-ZAN WANG, CHI-FANG LIN, JA-CHEN LIN Image hiding by optimal LSB substitution and genetic algorithm. Pattern Recognition, 2001, vol. 34, p. 671-683.
15. CHIN-CHEN CHANG, JU-YUAN HSIAO, CHI-SHIANG CHAN Finding optimal least-significant-bit substitution in image hiding by dynamic programming strategy. Pattern Recognition, 2003, vol. 36, p.1538-1595.
16. CHIN-CHEN CHANG, CHI-SHIANG CHAN, YI-HSUAN FAN Image hiding scheme with modulus function and dynamic programming strategy on partitioned pixels. Pattern Recognition, 2006, vol. 39, no. 6, p. 1155-1167.
17. CHI-KWONG CHAN, L. M. CHENG. Improved hiding data in images by optimal moderately-significant-bit replacement. IEE electronics letters, 2001, vol. 37, no. 16, p. 1017-1018.
18. CHI-KWONG CHAN, L. M. CHENG Hiding data in images by simple LSB substitution. Pattern Recognition, 2004, vol. 37, p. 469-474.
19. WEN-NUNG LIE, LI-CHUN CHANG. Data hiding in images with adaptive numbers of least significant bits based on the human visual system. In Proc. IEEE Int. Conf. Image Processing. Kobe (Japan), October 24-28, 1999, p. 286-290.
20. LEE, Y. K., CHEN, L. H. High capacity image steganographic model. IEE Proc., Vis. Image Signal Process, 2000, vol. 147, no. 3, p. 288-294.
21. SHAO-HUI LIU, TIAN-HANG CHEN, HONG-XUN YAO, WEN GAO A variable depth LSB data hiding technique in images. In Proc. 2004 International Conference on Machine Learning and Cybernetics. Shanghai (China), Aug. 26-29, 2004, vol. 7, p. 3990-3994.
22. KEKRE, H. B., ARCHANA ATHAWALE, PALLAVI N. HALARNKAR Increased capacity of information hiding in LSB’s method for text and image. International Journal of Electrical, Computer, and Systems Engineering, 2008, vol. 2, no. 4, p. 246-249.
23. WU, D.C., TSAI, W. H. A steganographic method for images by pixel-value differencing. Pattern Recognit. Lett., 2003, vol. 24, no. 9-10, p. 1613–1626.
24. CHUNG-MING WANG, NAN-I WU, CHWEI-SHYONG TSAI, MIN-SHIANG HWANG A high quality steganographic method with pixel-value differencing and modulus function. Journal of Systems and Software, 2008, vol. 81, no. 1, p. 150-158.
25. CHIN-CHEN CHANG, TSENG, H.W. A steganographic method for digital images using side match. Pattern Recognition Letters, 2004, vol. 25, p.1431-1437.
26. PARK, Y. R., KANG, H. H., SHIN, S. U., KWON, K. R. A steganographic scheme in digital images using information of neighboring pixels. In Proc. International Conference on Natural Computation. Berlin (Germany), 2005, Springer-Verlag LNCS, vol. 3612, p. 962–968.
27. YANG, C. H., WENG, C. Y. A steganographic method for digital images by multi-pixel differencing. In Proc. International Computer Symposium. Taipei (Taiwan), December, 2006, p. 831 to 836.
28. KI-HYUN JUNG, KYEOUNG-JU HA, KEE-YOUNG YOO Image data hiding method based on multi-pixel differencing and LSB substitution methods. In Proc. 2008 International Conference on Convergence and Hybrid Information Technology (ICHIT '08). Daejeon (Korea), Aug. 28-30, 2008, p. 355-358.
29. WU, H.-C., WU, N.-I., TSAI, C.-S., HWANG, M.-S. Image steganographic scheme based on pixel-value differencing and LSB replacement methods. IEE Proceedings-Vision, Image and Signal Processing, 2005, vol. 152, no. 5, p. 611-615.
30. CHENG-HSING YANG, CHI-YAO WENG, SHIUH-JENG WANG, HUNG-MIN SUN Adaptive data hiding in edge areas of images with spatial LSB domain systems. IEEE Transactions on Information Forensics and Security, 2008, vol. 3, no. 3, p. 488-497.
31. SHAH TRIIEHI, CHANDRAMOULI, R. Active steganalysis of sequential steganography. In Proc. SPIE-IS&T Electronic Imaging: Security and Watermarking of Multimedia Contents V, Santa Clara (CA), Jan. 2003, SPIE vo1.5020, p. 123-130.
32. LAHOUARI GHOUTI, AHMED BOURIDANE, MOHAMMAD K. IBRAHIM Edge-preserving wavelet-based multisensor image fusion approach. In Proc. EUSIPCO 2004, 12th European Signal Processing Conference. Vienna (Austria), September 6-10, 2004, p. 61-64.
33. SHENG-NAN YE, KAINA SU, CHUANG-BAI XIAO Video quality assessment based on edge structural similarity. In Proc. 2008 Congress on Image and Signal Processing. Sanya, Hainan (China), May 27-30, 2008, vol. 3, p. 445-448.
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Keywords: Data Hiding, Adaptive Least Significant Bits Substitution, Human Visual System, High Embedding Capacity, Optimal Pixel Adjustment Process.

E. Ferdinandov, K. Dimitrov, A. Dandarov, I. Bakalski [references] [full-text] [Download Citations]
A General Model of the Atmospheric Scattering in the Wavelength Interval 300 - 1100nm

We have presented and developed new theoretic-empirical models of the extinction coefficients of the molecular scattering in the lower, close to the ground troposphere. We have included the indicatrices of backscattering. The models have been presented using general analytical functions valid for the whole wavelength interval 300-1100 nm and for the whole interval of visibility from 0.1 km up to 50 km. The results have been compared in quantity with the model and experimental data of other authors. The modeling of troposphere scattering is necessary for the analysis and design of all optoelectronic free space systems: atmospheric optical communication systems, location systems for atmospheric research (LIDAR), optical radiometric systems.

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Keywords: Model, extinction, atmosphere, visibility, lidar.

A. Lahiri [references] [full-text] [Download Citations]
Explicit-Current-Output Quadrature Oscillator Using Second-Generation Current Conveyor Transconductance Amplifier

This paper presents a novel quadrature sinusoidal oscillator using second-generation current conveyor transconductance amplifier as an active building block. The proposed circuit employs only a single second-generation current conveyor transconductance amplifier, four passive components. The proposed circuit offers the advantages of independent control of the condition of oscillation and frequency of oscillation, availability of two explicit quadrature current outputs and two quadrature voltages, use of allgrounded passive elements and low active and passive sensitivities. The workability of the proposed circuit is confirmed by SPICE simulations.

1. SENANI, R., SINGH, V. K. Single-element-controlled sinusoidal oscillator employing a single current conveyor IC. Electronics Letters, 1992, vol. 29, no. 14, p. 414-415.
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6. GUPTA, S. S., SENANI, R. State variable synthesis of single-resistancecontrolled grounded capacitor oscillators using only two CFOAs: additional new realisations. IEE Proc. Circuits, Devices and Systems, 1998, vol. 145, p. 415-418.
7. GUPTA, S. S., SENANI, R. Novel SRCOs using first generation current conveyor. International Journal of Electronics, 2000, vol. 87, no. 10, p. 1187-1192.
8. BHASKAR, D. R. Realisation of second-order sinusoidal oscillator/filters with non-interacting controls using CFAs. Frequenz: Journal of Telecommunications, 2003, vol. 57, no. 1/2, p. 12-14.
9. SINGH, V. K., SHARMA, R. K., SINGH, A. K., BHASKAR, D. R., SENANI, R. Two new canonic single-CFOA oscillators with single resistor controls. IEEE Trans. on Circuits and Systems II: Express Brief, 2005, vol. 52, no. 12, p. 860-864.
10. BHASKAR, D. R., SENANI, R. New CFOA-Based Single-Element-Controlled Sinusoidal Oscillators. IEEE Trans. Instrument. and Meas., 2006, vol. 55, no. 6, p. 2014-2021.
11. PRASAD, D., BHASKAR, D. R., SINGH, A. K. Realisation of single-resistance-controlled sinusoidal oscillator: a new application of the CDTA. WSEAS Transaction on Electronics, 2008, vol. 5, no. 6, p. 257-259.
12. YUCE, E., MINAEI, S. A modified CFOA and its applications to simulated inductors, capacitance multipliers, and analog filters. IEEE Trans. on Circuits and Syst. I, 2008, vol. 55, no. 1, p. 266-275.
13. BHUSAN, M., NEWCOMB, R. W. Grounding of capacitors in integrated circuits. Electronics Letters, 1967, vol. 3, p. 148-149.
14. SOLIMAN, A. M. New grounded capacitor current mode band-pass low-pass filters using two balanced output ICCII. Journal of Active and Passive Electronic Devices, 2008, vol. 3, p. 175-184.
15. TANGSRIRAT, W., PRASERTSOM, D., PIYATAT, T., SURAKOMPONTORN, W. Single-resistance-controlled quadrature oscillators using current differencing buffered amplifiers. International Journal of Electronics, 2008, vol. 95, no. 11, p. 1119-1126.
16. PROKOP, R., MUSIL, V. New modern circuit block CCTA and some its applications. In Proceedings of Fourteenth International Scientific and Applied Science Conference - Electronics ET’2005, Book 5. Sofia (Bulgaria), 2005, p. 93-98.
17. PROKOP, R., MUSIL, V. Modular approach to design of modern circuit blocks for current signal processing and new device CCTA. In Proceedings of the Seventh IASTED International Conference on Signal and Image Processing. Anaheim (USA), 2005, p. 494-499.
18. JAIKLA, W., SILAPAN, P., CHANAPROMMA, C., SIRIPRUCHYANUN, M. Practical implementation of CCTA based on commercial CCII and OTA. In Proceedings of International Symposium on Intelligent Signal Processing and Communication Systems. Bangkok (Thailand), 2008.
19. BIOLEK, D., SENANI, R., BIOLKOVA, V., KOLKA, Z. Active elements for analog signal processing: classification, review, and new proposals. Radioengineering, 2008, vol. 17, no. 4, p. 15-32.
20. TANGSRIRAT, W., SURAKAMPONTORN, W. Single-resistance-controlled quadrature oscillator and universal biquad filter using CFOAs. AEU-Int. J. Electron. Commun., 2008, doi:10.1016/j.aeue.2008.08.006
21. ACAR, C., OZOGUZ, O. A new versatile building block: current differencing buffered amplifier. Microelectronics Journal, 1999, vol. 30, p. 157-160.
22. TANGSRIRAT, W. CDBA-based quadrature sinusoidal oscillator. Frequenz, 2007, vol. 61, p. 102-104.
23. TANGSRIRAT, W., PRASERTOSM, D., PIYATAT, T., SURAKAM-PONTORN, W. Single-resistance-controlled quadrature oscillator using current differencing buffered amplifiers, International Journal of Electronics, 2008, vol. 95-11, p. 1119-1126.
24. LAHIRI, A., MISRA, A., GUPTA, K. Novel current-mode quadrature oscillators with explicit-current-outputs using CCCDTA. In Proceedings of 19th International Radioelektronika Conference. Bratislava (Slovakia), 2009, p. 47-50.
25. LAHIRI, A. Novel voltage/current-mode quadrature oscillator using current differencing transconductance amplifier. Analog Integrated Circuts and Signal Processing, 2009, doi: 10.1007/s10470-009-9291-0
26. FREY, D. R. Log-domain filtering: an approach to current mode filtering. IEE Proceedings-Circuits, Devices and Systems, vol. 140, no. 6, pp. 406-416, 1993.

Keywords: Single-element-controlled oscillators (SECOs), singleresistance-controlled oscillators (SRCOs), quadrature oscillators, second-generation current conveyor transconductance amplifier (CCII-TA).

B. Liu, C. Wang, M. Ma, S. Guo [references] [full-text] [Download Citations]
An Ultra-Low-Voltage and Ultra-Low-Power 2.4 GHz LNA Design

In this paper, ultra-low-voltage and ultra-low-power circuit techniques are presented for CMOS RF front-ends. By employing a modified current-reused architecture, the low-noise amplifier (LNA) can operate at a very low supply voltage with microwatt power consumption while maintaining reasonable circuit performance at 2.4 GHz. Using a TSMC 0.18 um CMOS process, from the simulation results, the fully integrated LNA exhibits a gain of 14.4 dB and a noise figure of 1.6 dB at 2.4 GHz, operated at a supply voltage of 0.9 V, the input matching (S11) is –18.1 dB while consumes only 960 μW. example.

1. ASGARAN, S., DEEN, M. J., CHEN, C.-H. Design of the input matching network of RF CMOS LNAs for low-power operation. IEEE Transactions on Circuits and Systems, 2007, vol. 54, no. 3, p. 350 - 353.
2. KAAMOUCHI, M. E., MOUSSA, M. S., DELATTE, P. et al. A 2.4-GHz fully integrated ESD-protected low-noise amplifier in 130-nm PD SOI CMOS technology. IEEE Transactions on Microwave Theory and Techniques, 2007, vol. 55, no. 12, p. 2822 - 2831.
3. CIMINO, M., LAPUYADE, H., DEVAL, Y. et al. Design of a 0.9 V 2.45 GHz self-testable and reliability-enhanced CMOS LNA. IEEE Journal of Solid-State Circuits, 2008, vol. 43, no. 5, p. 1187 - 1194.
4. FENG, Y., TAKEMURA, G., KAWAGUCHI, S. KINGET, P. Design of a high performance 2-GHz direct-conversion front-end with a single-ended RF input in 0.13um CMOS. IEEE Journal of Solid-State Circuits, 2009, vol. 44, no. 5, p. 1380 - 1390.
5. GIANESELLO, F., GLORIA, D., RAYNAUD, C., BONER, S. 5 GHz 1.4 dB NF CMOS LNA integrated in 130 nm high resistively SOI technology. In International Integrated Circuits symposium, 2007, p. 96 - 99.
6. ASGARAN, S., DEE, M. J., CHEN C.-H. A 4-mW monolithic CMOS LNA at 5.7 GHz with the gate resistance used for input matching. IEEE Microwave and Wireless Components Letters, 2006, vol. 16, no. 4, p. 188 - 190.
7. HSIEH, H.-H., WANG, J.-H., LU, L.-H. Gain-enhancement techniques for CMOS folded cascode LNAs at low-voltage operations. IEEE Transactions on Microwave Theory and Techniques, 2008, vol. 56, no. 8, p. 1807 - 1816.
8. WU, D., HUANG, R., WONG, W., WANG, Y. A 0.4-V low noise amplifier using forward body bias technology for 5 GHz application, IEEE Microwave and Wireless Components Letters, 2007, vol. 17, no. 7, p. 543 - 545.
9. HSIEH, H.-H., LU, L.-H. Design of ultra-low-voltage RF frontends with complementary current-reused architectures, IEEE Transactions on Microwave Theory and Techniques, 2007, vol. 55, no. 7, p. 1445 - 1458.
10. WEI, M.-D., CHANG, S.-F., LIU, C.-H. A low-power ultracompact CMOS LNA with shunt-resonating current-reused topology. In IEEE the 3rd European Microwave Integrated Circuits Conference, 2008, p. 350 - 353.
11. CHU, C.-Y., WEI, C.-C., HSU, H.-C. et al. A 24GHz low-power CMOS receiver design. In IEEE International symposium of Circuits and system, 2008, p. 980 - 983.
12. CHANG, C.-P., CHEN, J.-H., WANG, Y.-H. A fully integrated 5 GHz low-voltage LNA using forward body bias technology. IEEE Microwave and Wireless Components Letters, 2009, vol. 19, no. 3, p. 176 - 178.
13. WANG, Y. S., LU, L.-H. 5.7 GHz low-power variable-gain LNA in 0.18 um CMOS. IEEE Electronics Letters, 2005, vol.41, no. 2, p. 66 - 68.
14. CHA, C.-Y., LEE, S.-G. A 5.2GHz LNA in 0.35 μm CMOS utilizing inter-stage series resonance and optimizing the substrate resistance. In IEEE Solid-State Circuits Conference, 2002, p. 339 - 342.
15. KAO, C.-Y., CHIANG, Y.-T., YANG, J.-R. A concurrent multiband low-noise amplifier for WLAN/WiMAX applications. IEEE International Conference of Electro/Information Technology, 2008, p. 514 - 517.
16. LEE, H., MOHAMMADI, S. A 3GHz subthreshold CMOS low noise amplifier. In Radio Frequency Integrated Circuits (RFIC) Symposium, 2006, p. 4.
17. NGUYEN, T.-K., KIM, C.-H., IHM, G.-J. CMOS low-noise amplifier design optimization techniques. IEEE Transactions on Microwave Theory and Techniques, vol. 52, no. 5, 2004, p. 1433 - 1442.
18. WU, D.-K., HUANG, R., WANG, Y.-Y. A low-voltage and low-power CMOS LNA using forward-body-bias NMOS at 5GHz. In International Conference of Solid-State and Integrated Circuit Technology, 2006, p. 1658 - 1660.

Keywords: Low-noise amplifier, low power, low voltage, low noise.

Q. Wan, C. Wang, M. Ma [references] [full-text] [Download Citations]
A Novel 2.4GHz CMOS Up-Conversion Current-Mode Mixer

In this paper, a low-power up-conversion current-mode mixer, designed in the chartered 0.18-μm RFCMOS technology, is proposed to realize the transmitter front-end in the frequency band of 2.4 GHz. The proposed mixer can convert a 10 MHz intermediate frequency (IF) signal to a 2.4 GHz RF signal, with a local oscillator power of 2 dBm at 2.39 GHz. A comparison with conventional voltage-mode up-conversion mixer shows that this mixer has advantages of low voltage, low power consumption and high performance. Simulation results demonstrate that at 2.4 GHz, the circuit provides 6.5 dB of conversion gain and the input-referred third-order intercept point (IIP3) of 15.3 dBm, while drawing only 5.7 mA from a 1.2V supply voltage. The chip area is only 0.7 mm x 0.8 mm.

1. BEHBAHANI, F., KISHIGAMI, Y., LEETE, J., ABIDI, A. A. CMOS mixers and polyphase filters for large image rejection. IEEE J. Solid-State Circuits, 2001, vol. 36, no. 6, p. 873 to 887.
2. LE VIET HOANG, NGUYEN TRUNG KIEN, SOK-KYUN HAN, SANG-GUG LEE, HYUN, S. B. Low power high linearity transmitter front-end for 900 MHz Zigbee applications. IEEE International Symposium on Circuits and Systems, 2006.
3. GILBERT, B. A precise four-quadrant multiplier with subnanosecond response. IEEE Journal of Solid-State Circuits, 1968, vol. SC-3, no.4, p. 365–373.
4. CHIH-MING LIN, HUNG-JU WE, YI-TING WANG, SHYH- CHYI WANG, YEONG-HER WANG A novel doubly-balanced folded mixer for low supply voltage and direct up-conversion system. In 8th Int. Conf. on Solid-State and Integrated Circuit Technology, 2006, p. 1562-1564.
5. S.H.-L. TU, S. C.-H. CHEN. A 5.26-GHz CMOS up-conversion mixer for IEEE 802.11a WLAN. In 4th IEEE Int. Conf. on Circuits and Systems for Communications, 2008, p. 820-823.
6. MEI-LING YEH, SHENG-HING KUO, WAN-RONE LIOU. A low-voltage 5-GHz quadrature up-conversion mixer for wireless transmitter. In Proceedings of the Int. Conf. on Communications, Circuits and Systems, 2006, vol.4, p. 2618-2622.
7. SHAHROURY, F.R., CHUNG-YU WU The design of low LO- power 60-GHz CMOS quadrature-balanced self-switching currentmode mixer. IEEE Microwave and Wireless Components Letters, 2008, vol. 18, no. 10, p. 692-694.
8. WANG-CHI CHENG, CHEONG-FAT CHAN, CHIU-SING CHOY, KONG-PANG PUN A 900 MHz 1.2 V CMOS mixer with high linearity. In IEEE Asia Pacific Conf. on Circuits and Systems, 2002, vol. 1, p. 1-4.
9. WANG-CHI CHENG, CHEONG-FAT CHAN, KONG-PANG PUN, CHIU-SING CHOY Sub-1 V current mode CMOS integrated receiver front-end for GPS system. In IEEE Asia Pacific Conf. on Circuits and Systems, 2006, p. 195-198.
10. BULT, K., WALLINGA, H. A class of analog CMOS circuits based on the square-law characteristic of an MOS transistor in saturation. IEEE J. Solid-State Circuits, 1987, vol. 22, no. 3, p.357–365.
11. WEN-CHIEH WANG, CHUNG-YU WU. The 1-V 24-GHz lowvoltage low-power current-mode transmitter in 130-nm CMOS technology. In Research in Microelectronics and Electronics Conference, 2007, p.49-52.
12. GIUSTOLISI, G., PALMISANO, G., PENNISI, S. High-linear class AB transconductor for high-frequency applications. IEEE Int. Symp. on Circuits and Systems, 2000, vol. 5, p. 169-172.
13. HONG ZHANG, GUICAN CHEN, XIAO YANG. Fully differential CMOS LNA and down-conversion mixer for 3-5 GHz MB-OFDM UWB receivers. In IEEE International Workshop on Radio-Frequency Integration Technology, 2007, p.54-57.
14. WEI ZHUO, EMBABI, S., DE GYVEZ, J. P., SANCHEZ- SINENCIO, E. Using capacitive cross-coupling technique in RF low noise amplifiers and down-conversion mixer design. In Proc. of the 26th European Solid-State Circuits Conf., 2000, p. 77-80.
15. XIAOHUA FAN, HENG ZHANG, E.SANCHEZ-SINENCIO. A noise reduction and linearity improvement technique for a differential cascode LNA. IEEE Journal of Solid-State Circuits, 2008, vol. 43, no. 3, p.588–599.

Keywords: Current-mode mixer, up-conversion mixer, CMOS, high linearity, low power.

J. Horng [references] [full-text] [Download Citations]
High-Order Current-Mode and Transimpedance-Mode Universal Filters with Multiple-Inputs and Two-Outputs Using MOCCIIs

A high-order current-mode and transimpedance-mode universal filter with multiple-inputs and two-outputs based on multiple output second-generation current conveyors (MOCCIIs) is introduced. By choosing the input current terminals appropriately, the current-mode and transimpedance-mode lowpass, bandpass, highpass, notch or allpass filters can be obtained without component matching conditions. The proposed nth order universal filter requires (n+1) MOCCIIs, (n+1) resistors and n grounded capacitors. As examples, the first-order, biquadratic and third-order universal filters are given and compared with previous published works.

1. TOUMAZOU, C., LIDGEY, F. J., HAIGH, D. G. Analog IC Design: The Current-Mode Approach. Peter Peregrinus Ltd., London, 1990.
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3. ACAR, C. Nth-order lowpass voltage transfer function synthesis using CCII+s: signal-flow graph approach. Electronics Letters, 1996, vol. 32, p. 159-160.
4. ANDAY, F., GUNES, E. O. Realization of nth-order transfer functions using current conveyors. International Journal of Circuit Theory and Applications, 1992, vol. 20, p. 693-696.
5. GUNES, E. O., ANDAY, F. Realisation of nth-order voltage transfer function using CCII+. Electronics Letters, 1995, vol. 31, p. 1022-1023.
6. ACAR, C., OZOGUZ, S. High-order voltage transfer function synthesis using CCII+ based unity gain current amplifiers. Electronics Letters, 1996, vol. 32, p. 2030-2031.
7. GUNES, E. O., ANDAY, F. An nth-order allpass voltage transfer function synthesis using commercially available active components. Microelectronics Journal, 1999, vol. 30, p. 895-898.
8. SVOBODA, J. A., MCGORY, L., WEBB, S. Applications of a commercially available current conveyor. International Journal of Electronics, 1991, vol. 70, p. 159-164.
9. NANDI, R. Insensitive current mode realization of third-order Butterworth characteristics using current conveyors. IEEE Transactions on Circuits and Systems-I: Fundamental Theory and Applications, 1994, vol. 41, p. 925-927.
10. NANDI, R. Precise insensitive current-mode third-order lowpass Butterworth characteristics. IEE Proceedings-Circuits Devices and Systems, 1996, vol. 143, p. 223-224.
11. GUNES, E. O., ANDAY, F. Realisation of current-mode low pass filters using CFCCIIs. Electronics Letters, 1995, vol. 31, p. 2161 to 2162.
12. WU, J., EL-MASRY, E. Current-mode ladder filters using multiple output current conveyors. IEE Proceedings-Circuits Devices and Systems, 1996, vol. 143, p. 218-222.
13. HWANG, Y. S., HUNG, P. T., CHEN, W., LIU, S. I. Systematic generation of current-mode linear transformation filters based on multiple output CCIIs. Analog Integrated Circuits and Signal Processing, 2002, vol. 32, p. 123-134.
14. BHUSAN, M., NEWCOMB, R. W. Grounding of capacitors in integrated circuits. Electronic Letters, 1967, vol. 3, p. 148-149.
15. YUCE, E. Grounded inductor simulators with improved lowfrequency performances. IEEE Transactions on Instrumentation and Measurement, 2008, vol. 57, p. 1079-1084.
16. CHANG, C. M., CHEN, P. C. Universal active current filter with three inputs and one output using current conveyors. International Journal of Electronics, 1991, vol. 71, p. 817-819.
17. CHANG, C. M., CHIEN, C. C., WANG, H. Y. Universal active current filter with three inputs using current conveyors-part 2. International Journal of Electronics, 1994, vol. 76, p. 87-89.
18. ABUELMA’ATTI, M. T., TASADDUQ, N. A. A novel three inputs and one output universal current-mode filter using plus-type CCIIs. Microelectronics Journal, 1999, vol. 30, p. 287-292.
19. CHANG, C. M. Universal active current filter with three inputs and one output using plus-type CCIIs. Electronics Letters, 1997, vol. 33, p. 1207-1208.
20. ABUELMA’ATTI, M. T., BENTRCIA, A., AL-SHAHRANI, S. M. A novel mixed-mode current-conveyor-based filter. International Journal of Electronics, 2004, vol. 91, p. 191-197.
21. WANG, H. Y., LEE, C. T. Versatile insensitive current-mode universal biquad implementation using current conveyor. IEEE Transactions on Circuits and Systems-II: Analog and Digital Signal Processing, 2001, vol. 48, p. 409-413.
22. FABRE, A., SAAID, O., WIEST, F., BOUCHERON, C. High frequency applications based on a new current controlled conveyor. IEEE Transactions on Circuits and Systems-I: Fundamental Theory and Applications, 1996, vol. 43, p. 82-91.
23. SURAKAMPONTORN, W., RIEWRUJA, V., KUMWACHARA, K., DEJHAN, K. Accurate CMOS-based current conveyors. IEEE Transactions on Instrumentation and Measurement, 1991, vol. 40, p. 699–702.

Keywords: Current conveyor, high-order filter, current-mode, transimpedance-mode.

M. Hosseinipanah, Q. Wu [references] [full-text] [Download Citations]
Equivalent Circuit Model for Designing of Jerusalem Cross-Based Artificial Magnetic Conductors

This paper introduces an equivalent circuit model to estimate the resonant frequency and reflection phase of Jerusalem cross-based artificial magnetic conductor (JC-AMC) structures for waves normally incident on the structure. The JC-AMC structure is composed of an array of Jerusalem cross-shaped frequency selective surfaces (JC-FSSs) printed on a metal-backed dielectric slab without vias. This approach is based on the coupled microstrip lines and transmission line theories. Analytical expressions for the resonant frequency and reflection phase resulting from our model are thoroughly verified by full-wave simulations for different samples reported in the open literature. A comprehensive parametric study of the design parameters of JC-AMC structure and the influence of these parameters on the reflection phase properties are presented. This model can easily be extended to complex-shaped AMCs.

1. SIEVENPIPER, D.F., ZHANG, L.J., BROAS, R.F.J., ALEXOPOLOUS, N. G., YABLONOVITCH, E. High-impedance electromagnetic surfaces with a forbidden frequency band. IEEE Trans. Microwave Theory & Techn., 1999, vol. 47, no. 11, p. 2059-2074.
2. SIEVENPIPER, D. High-impedance electromagnetic surfaces. Ph.D. dissertation, Univ. Calif., Los Angeles, 1999.
3. LUUKKONEN, O., SIMOVSKI, C., GRANET, G., GOUSSETIS, G., LIOUBTCHENKO, D., RAISANEN, A. V., TRETYAKOV, S. A. Simple and accurate analytical model of planar grids and high-impedance surfaces comprising metal strips or patches. IEEE Trans. Antennas & Propag., vol. 56, no. 6, p. 1624 – 1632.
4. SIMOVSKI, C. R., SOCHAVA, A. A. High-impedance surfaces based on self-resonant grids. Analytical modelling and numerical simulations. Progress in Electromagnetics Research (PIER) 2003, vol. 43, p. 239–256.
5. ENGHETA, N., ZIOLKOWSKI, R. W. Metamaterials: Physics and Engineering Explorations. IEEE press published by Wiley-Interscience, 2006.
6. HOSSEINI, M., HAKKAK, M. Characteristics estimation for Jerusalem cross-based artificial magnetic conductors. IEEE Antenna and Wireless Propagation Letters, 2008. vol. 7, p 58-61.
7. SIMOVSKI, C. R., MAAGT, P. D., MELCHAKOVA, I. V. Highimpedance surfaces having stable resonance with respect to polarization and incidence angle. IEEE Transaction on Antennas Propagation, 2005, vol. 53, no. 3, p. 908-914.
8. GUPTA, K. C., GARG, R., BAHL, I., BHARTIA, P. Microstrip Lines and Slotlines. 2nd ed. Norwood: Artech House, 1996.
9. BAHL, I. Lumped Elements for RF and Microwave Circuit. Norwood: Artech House, 2003.
10. BAGGEN, R., MARTINEZ-VAZQUEZ, M., LEISS, J., HOLZWARTH, S. Comparison of EBG substrates with and without vias for GALILEO/GPS applications. In Proc. EuCAP 2007, 2nd European Conf. on Antennas and Propagation. Edinburgh (UK), 2007.
11. VALLECCHI, A., ALBANI, M., CAPOLINO, F. Planar metamaterial transverse equivalent network and its application to low-profile antenna designs. In Proc. EuCAP 2009 – the 3rd European Conf. on Antennas and Propagation. Berlin (Germany), 2009.

Keywords: Artificial magnetic conductor, electromagnetic bandgap, high-impedance surface, Jerusalem crosses, equivalent circuit model.

F. Yu, C. Wang [references] [full-text] [Download Citations]
A CPW-Fed Novel Planar Ultra-Wideband Antenna with a Band-Notch Characteristic

A coplanar waveguide (CPW) fed novel planar ultra-wideband antenna with a band-notch characteristic is presented. The proposed antenna consists of a rectangular metal radiation patch and a tapered arc-shaped ground plane. To achieve ultra wideband, three modifications are introduced, the first one is to remove a 90-degree fan angle on the upper corners of the patch, the second one is to shape the bottom of the patch into an arc, and the third modification is to remove a small fan angle on each side of the ground plane near the feeding line. Simulation results show that the proposed antenna operates over 3.0 to 23 GHz for VSWR < 2. By embedding a C-shaped slot in the radiating patch, a frequency band notch between the bandwidth of 5 to 6 GHz for Wireless LAN (WLAN) will be obtained. All simulations in this work were carried out by using the electromagnetic software Ansoft HFSS 11. Compared with the recently proposed antennas, this antenna has advantages in wide bandwidth, good band-notch characteristic, compact in size and easy design. Details of the proposed antenna are presented, and simulated results show that the antenna has stable radiation patterns and good gain flatness over its whole frequency band.

1. HUNG, K.-J., LIN, Y.-CH. Open-slot loaded monopole antennas for WLAN and UWB applications. In IEEE Antennas and Propagation Society International Symposium. Albuquerque (USA), 2006, p. 4653 - 4656.
2. ABBOSH, A. Planar ultra wideband antennas with rejected subbands. In IEEE Proceedings of Asia-Pacific Microwave Conference. Bangkok (Thailand), 2007.
3. YIN, K., XU, J. Compact ultra-wideband monopole antenna with band-stop characteristic. In International Conference on Microwave and Millimeter Wave Technology, vol. 3. Nanjing (China), 2008, p. 1174 - 1176.
4. ZAMEL, H. M., ATTIYA, A. M., HASHISH, E. A. Design of a compact UWB planar antenna with band-notch characterization. In Radio Science Conference. Cairo (Egypt), 2007, p. 1 – 8.
5. CHU, Q.-X., YANG, Y.-Y. A compact CPW-fed planar ultrawideband antenna with a frequency notch characteristic. In Proceedings of Asia-Pacific Microwave Conference. Bangkok (Thailand), 2007.
6. CHOI, S. H., LEE, H. J., KIM, J. K. Design of an ultra-wideband antenna with band notch characteristic. In IEEE Antennas and Propagation Society International Symposium. San Diego (USA), 2008, p. 1 - 4.
7. JAFARI, H. M., DEEN, M. J., HRANILOVIC, S., NIKOLOVA, N. K. Slot antenna for ultra-wideband applications. In IEEE Antennas and Propagation Society International Symposium. Albuquerque (USA), 2006, p. 1107 - 1110.
8. YOON, H., KIM, H., CHANG, K., YOON, Y. J., KIM, Y.-H. A study on the UWB antenna with band-rejection characteristic. In IEEE Antennas and Propagation Society International Symposium, vol. 2. Monterey (USA), 2004, p. 1784 - 1787.
9. HONG, C.-Y., LING, C.-W., CHUNG, S.-J. Design of a planar ultra wideband antenna with a new band-notch structure. IEEE Transactions on Antennas and Propagation, 2007, vol. 55, no. 12, p. 3391 - 3397.

Keywords: Keywords Coplanar waveguide (CPW), ultra wideband (UWB), planar UWB antenna, C-shaped slot, band-notched characteristic.

V. Ricny [references] [full-text] [Download Citations]
Maximum Available Accuracy of FM-CW Radars

This article deals with the principles and above all with the maximum available measuring accuracy analyse of FM-CW (Frequency Modulated Continuous Wave) radars, which are usually employed for distance and velocity measurements of moving objects in road traffic, as well as air traffic and in other applications. These radars often form an important part of the active safety equipment of high-end cars – the so-called anticollision systems. They usually work in the frequency bands of mm waves (24, 35, 77 GHz). Function principles and analyses of factors, that dominantly influence the distance measurement accuracy of these equipments especially in the modulation and demodulation part, are shown in the paper.

1. de WIT, W. M. Linearization of an FM-CW 94,5 GHz Millimetre Wave Radar, thesis for the degree of MSc. Department of IEEE, University Stellenbosch, 2006.
2. VIQUERAT, A. et al. Reactive collision avoidance for unmanned aerial vehicles using doppler radar. In Proceedings of the 6th International Scientific Conference FSR 2007, Chamonix (France), 2007.
3. LISSEL, E., ROHLING, H., LAGGE, W. Radar sensor for car applications. In Proceedings of the Vehicular Technology Conference IEEE, Stockholm (Sweden), 1994.
4. ELVA-1, Russia. El94 GHz FMCW Radar Module. (datasheet). [Online] 2001. Available at http://www.elva-1.spb.ru .
5. University of St. Andrews, UK. Radar and Ranging. The Scots Guide to Electronics. 1999. Available at http://www.st-andrews. ac.uk/~www_pa/Scots_Guide/ .
6. GORJESTANI, A. et al. Evaluation of Radar for Snowplows – Initial Results, technical report. Minnesota (USA): Department of Mechanical Engineering, University of Minnesota, 1998.
7. RICNY,V. Presna vyskomerna soustava (Precise Altimeter), thesis for the degree of MSc. Department of Radio Electronics, Brno Technical University, 1973.
8. NATHANSON, F. et al. Radar Design Principles: Signal Processing and Environment. E-book. Raleigh (USA): SciTech Publishing, 1999.
9. RICHARDS, M. A. Fundamentals of Radar Signal Processing. New York: McGraw-Hill, 2005.
10. LEVANON, N., MOZESON, E. Radar Signals. London: John Wiley, 2004.
11. SKOLNIK, M. I. Introduction to Radar Systems. 3rd ed. New York: McGraw-Hill, 2003.

Keywords: FM-CW radar, continual wave, frequency modulation, measurement, distance, velocity.

J. Pidanic, V. Schejbal, D. Cermak [references] [full-text] [Download Citations]
Analysis of Periodic Errors for Synthesized-Reference-Wave Holography

Synthesized-reference-wave holographic techniques offer relatively simple and cost-effective measurement of antenna radiation characteristics and reconstruction of complex aperture fields using near-field intensity-pattern measurement. These methods allow utilization of advantages of methods for probe compensations for amplitude and phasing near-field measurements for the planar and cylindrical scanning including accuracy analyses. The paper analyzes periodic errors, which can be created during scanning, using both theoretical results and numerical simulations.

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17. SCHEJBAL, V., PIDANIC, J., KOVARIK, V., CERMAK, D. Accuracy analyses of synthesized-reference-wave holography for determining antenna radiation characteristics. IEEE Antennas & Propag. Magazine, 2008, vol. 50, no. 6, pp. 89- 98.
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Keywords: Periodic errors, numerical simulations, accuracy analyses, near-field sampling, holography.

J. L. Jimenez-Martin, V. Gonzalez-Posadas, F. J. Arques, L. E. Garcia-Munoz, D. Segovia-Vargas [references] [full-text] [Download Citations]
Dual Band High Efficiency Power Amplifier Based on CRLH Lines

In this paper we propose the use of Composite Right/Left Hand (CRLH) and Extended Composite Right/Left Hand (ECRLH) transmission lines for the design of dual band high efficiency power amplifiers working in CE class. The harmonic termination can be synthesized using the meta-lines is particularly suitable for CE class amplifiers, which have a termination not as sensitive to the third harmonic as F class amplifier. This paper presents the design procedure and the design equations. The nonlinear phase response of a CRLH and ECRLH transmission line has been utilized to design arbitrary dual-band amplifiers.

1. FUKUDA, A., OKAZAKI, H., HIROTA, T., YAMAO, Y., QIN, Y., GAO, S., SAMBELL, A., KOROLKIEWICZ, E. Novel 900 MHz/1.9 GHz dual-mode power amplifier employing MEMS switches for optimum matching. IEEE Microw. Wireless Compon. Lett., Mar.2004, vol. 14, no. 3, pp. 121–123.
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4. LIN, I., DEVINCENTIS, M., CALOZ, C., ITOH, T. Arbitrary dual-band components using composite right/left handed transmission lines. IEEE Trans. Microw. Theory Tech., Apr. 2004, vol. 50, no. 4, pp. 1142–1149.
5. SEUNG HUN JI, CHOON SIK CHO, LEE, J. W., JAEHEUNG KIM Concurrent dual-band class-E power amplifier using composite right/left-handed transmission lines. IEEE Transactions on Microwave Theory and Techniques, June 2007, vol. 55, no. 6, part 2, pp.1341 – 1347.
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Keywords: eywords Power Amplifier, Meta-materials, CE class, CRLH, ECRLH, Diplexer, Statistical Sensitivity.

J. Svihlik [references] [full-text] [Download Citations]
Modeling of Scientific Images Using GMM

This paper deals with modeling of scientific and multimedia images in the wavelet domain. Images transformed into wavelet domain have a special shape of probability density function (PDF). Thus wavelet coefficients PDFs are usually modeled using generalized Laplacian PDF model (GLM), which is characterized by two parameters. The wavelet coefficients modeling can be more efficient, while the Gaussian mixture model (GMM) is utilized. GMM model is given by addition of at least two Gaussian PDFs with different standard deviations. The equation system derived by moment method for GMM model parameters estimation will be presented. The equation system was derived for an addition of two GMM models. So it is suitable for advanced denoising systems, where an addition of two GMM random variables is considered (e.g. dark current). This paper presents a continuing of previous work [11], deals with dark current elimination (novel approach) and shows a better way of to modeling light image and dark current.

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9. SAME, A., OUKHELLOU, L., C ME, E., AKNIN, P. Mixture-model-based signal denoising. Advances in Data Analysis and Classification. Springer, March 2007, vol. 1, no. 1, p. 39-51.
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11. SVIHLIK, J., PATA, P. Elimination of thermally generated charge in charged coupled devices using Bayesian estimator. Radioengineering. June 2008, vol. 17, no. 2, p. 119 - 124.
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Keywords: Gaussian mixture model, discrete wavelet transform, moment method, ML method, dark current.

O. Yildiz, A. E. Yilmaz, B. Gokalp [references] [full-text] [Download Citations]
State-of-the-Art System Solutions for Unmanned Underwater Vehicles

Unmanned Underwater Vehicles (UUVs) have gained popularity for the last decades, especially for the purpose of not risking human life in dangerous operations. On the other hand, underwater environment introduces numerous challenges in navigation, control and communication of such vehicles. Certainly, this fact makes the development of these vehicles more interesting and engineering-wise more attractive. In this paper, we first revisit the existing technology and methodology for the solution of aforementioned problems, then we try to come up with a system solution of a generic unmanned underwater vehicles.

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Keywords: Unmanned underwater vehicle, autonomous underwater vehicle, navigation, control and guidance, underwater communications, systems engineering, software framework.

R. Dolecek, J. Novak, O. Cerny [references] [full-text] [Download Citations]
Traction Permanent Magnet Synchronous Motor Torque Control with Flux Weakening

The paper deals with analysis of dynamic behavior of a feedback flux weakening control of PMSM traction drive for light vehicles. The PMSM flux weakening is very important for traction drives. Two torque control structures were analyzed - pure feedback control and feedback control with prediction of the field producing current component. The principles, control structures, simulation and experimental results are given.

1. TAKAO, K., URUGA, K. Gauge change EMU train outline. Railway Technical Research Institute Report, 2003, vol. 44, no. 3, p. 103-108.
2. YOSHIDA, K. Development of main circuit system using direct drive motor (DDM). JR East Technical Review, 2002, no. 1, p. 46-52.
3. OSAVA, M. Toward creation of a railway car meeting the 21st century requirements. JR East Technical Review, 2002, no. 1, p. 9-12.
4. SIMANEK, J., NOVAK, J., CERNY, O., DOLECEK, R. FOC and flux weakening for traction drive with permanent magnet synchronous motor. In IEEE International Symposium on Industrial Electronics. Cambridge (United Kingdom), 2008, p. 753 - 758.
5. MIHAILOVIC, Z. Modeling and Control Design of VSI-Fed PMSM Drive Systems with Active Load. M. S. Thesis. Virginia (USA): Virginia Polytechnic Institute and State University, 1999.
6. LETTL, J. Matrix converter hybrid drive system. WSEAS Transactions on Power Systems, 2006, vol. 1, no. 7, p. 1217-1222.
7. NOVAK, J., SIMANEK, J., CERNY, O., DOLECEK, R. EMC of frequency control electric drives. Radioengineering, 2008, vol. 17, no. 4, p. 101-105.

Keywords: Permanent magnet synchronous motor, traction drive, torque control, magnetic flux weakening, vector control.

J. Novak, R. Dolecek, O. Cerny [references] [full-text] [Download Citations]
EMC Specific Problems of Frequency Converters Used at Interlocking Device

The paper deals with problems of electromagnetic compatibility (EMC) of frequency control drive of electromotive switch actuator of railway switch. The frequency converter with Pulse Width Modulation (PWM) and the output sinus filter are used for feeding of the asynchronous motor of the switch actuator. This drive is operated in an insulated system of feeding voltages. The drive is fed by a frequency converter with an unshielded cable with length up to 1.2 km. The EMC problems occurring at development and operating of the drive are analyzed in this paper. The used solution of these problems and experience with EMC of the given system from real operation are described in this paper as well.

1. NOVAK, J., SIMANEK, J., CERNY, O., DOLECEK, R. EMC of frequency control electric drives. Radioengineering, 2008, vol. 17, no. 4, p. 101-105.
2. LETTL, J., DOLECEK, R. EMC increasing of PWM rectifier in comparison with classical rectifier. Radioengineering, 2008, vol. 17, no. 4, p. 93-100.
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4. NOVAK, J., STASTNY, J. Measurements at Drive of Electromotive Switch Actuator. Report for AZD, Prague, 1998, (in Czech).
5. KAISER, L., K. Electromagnetic Compatibility Handbook. CRC Press, USA, 2005, ISBN 0-8493-2087-9.
6. SHEPHERD, W., ZHANG, L. Power Converter Circuits. New York: Tailor and Francis, 2004, ISBN 0-8247-5054-3.
7. ELFIS s.r.o. Czech Republic. Report – Measurements of Interference according to EN 50121-3-1, no. 214/1998. July 1998, (in Czech).
8. ELFIS s.r.o. Czech Republic. Report – Measurements of Interference to cable, no. 215/1998. July 1998, (in Czech).
9. MOHAN, N., UNDELAND, M. T., ROBBINS, P. W. Power Electronics: Converters, Applications and Design. John Wiley and Sons, USA, 2003, ISBN 0-471-22693-9.
10. NOVAK, J. Measurements at Frequency Control of Switch Actuator of Railway Switch and Analysis of Faulted States. Report for AZD, Prague, 2003, (in Czech).
11. NOVAK, J. Analysis of Faults at the new Converters “Taian” for Drives of Switch Actuators of Railway Switches with Earthed Centre of Sinus Filter. Report for AZD, Prague, 2005, (in Czech).
12. NOVAK, J. Verification of Elimination Possibility of Faults at the New Converters “Taian” for Drives of Switch Actuators of Railway Switches under Conditions of Railway Station and Design of Structural Solution. Report for AZD, Prague, 2005, (in Czech).

Keywords: EMC, PWM, interlocking device, control system, converter, sinus filter, switch actuator, railway switch.

O. Jane, H. G. Ilk [references] [full-text] [Download Citations]
A Quantitative Study on Optimum Parameters Selection in Adaptive Unsharp Masking Technique for Infrared Images

Infrared image processing has been the focal point of considerable research activity in the last decade mainly because of its wide application areas in security and defense. With the aid of an existing image enhancement technique, we propose an optimum parameters selection procedure which delivers better performance in sharpness and contrast adjustment for the detection of targets in interest in objective quality metrics. Hence, proposed method ensures that the edges of the targets in infrared images are sharper and that the quality of contrast adjustment has its optimum level with minimum error.

1. JACKSON, J. S., COSGRIFF, R. L., BOSGESS, R. L., HAYMAN. Infrared techniques for surveillance and crime deterrence. IEEE Transaction on Industrial Electronics and Control Instrumentation, May 1971, vol. IECI-18, no. 2, p. 38 -42.
2. HUDSON, R. D. Infrared System Engineering. John Wiley & Sons, Inc., 1969.
3. KARALI, A. O., AYTAC, T. A comparison of different infrared image enhancement techniques for sea surface targets. In Signal Processing and Communications Applications Conference, SIU 9 - 11 April 2009, p. 765 – 768 (in Turkish).
4. POLESEL, A., RAMPONI, G., MATHEWS, V. J. Image enhancement via adaptive unsharp masking. IEEE Transactions on Image Processing, March 2000, vol. 9, no. 3, p. 505 – 510.
5. BADAMCHIZADEH, M. A., AGHAGOLZADEH, A. Comparative study of unsharp masking methods for image enhancement. In Proceedings of the IEEE Third International Conference on Image and Graphics. 18-20 December 2004, p. 27 to 30.
6. GONZALEZ, R. C., WOODS R. E. Digital Image Processing. Prentice Hall, Upper Saddle River, NJ, 2008.
7. LAMBRECHT, C. V. D. B. Perceptual models and architectures for video coding applications. Ph.D. dissertation, EPFL, Lausanne, Switzerland, 1996.
8. WIDROW, B., STEAMS, S. D. Adaptive Signal Processing. Englewood Cliffs, NJ: Prentice-Hall, 1985.
9. SINGH, M., SINGH, S. Optimizing image enhancement for screening luggage at airports. In Proceedings of the 2005 IEEE International Conference on Computational Intelligence for Homeland Security and Personal Safety, CIHSPS 2005, art. no. 1500627, p. 131 – 136.
10. SINGH, M., SINGH, S., PARTRIDGE, D. A comparison of image enhancement techniques for explosive detection. In Proceedings of the International Conference on Pattern Recognition 4, 2004, p. 811 – 814.
11. FERRARI, J. A., FLORES, J. L., PERCIANTE, C. D., FRINS, E. Edge enhancement and image equalization by unsharp masking using self-adaptive photochromic filters. Applied Optics 48 (19), 2009, p. 3570 – 3579.
12. SINGH, M., SINGH, S., PARTRIDGE, D. A knowledge-based framework for image enhancement in aviation security. IEEE Transactions on Systems, Man, and Cybernetics, Part B: Cybernetics 34 (6), 2004, p. 2354 – 2365.
13. FRANCISCO, G. L., BILLUPS, R. B., DEHORN, T., ANSTETT, F., O’HARA, M., FISHER, D. A. Thermal imaging for law enforcement and security, post 9-11. Proceedings of SPIE – The International Society for Optical Engineering 5071, 2003, p. 453 – 464.
14. HAYKIN, S. Adaptive Filter Theory. Prentice Hall, 2002.

Keywords: Adaptive filtering, surveillance applications, image enhancement, Gauss-Newton algorithm, minimum mean square error.

L. Drazan, R. Vrana [references] [full-text] [Download Citations]
Axial Vircator for Electronic Warfare Applications

This paper deals with a high power microwave generator with virtual cathode – vircator in axial release for electronic warfare applications. The classification of directed energy weapons microwave (DEWM) is introduced together with basic block diagrams of a particular class of DEWM. In the paper, methods for designing vircator pulsed power supply, axial vircator structure, measurement methods and experimental results are presented. The vircator in electromagnetic ammunition is powered by magneto-cumulative generator and in weapons for defense of objects (WDO), it is powered by Marx generator. The possible applications of a vircator in the DEWM area are discussed.

1. ADAMY, D. EW101: A First Course in Electronic Warfare. Norwood: Artech House, 2001.
2. GLASSTONE, S., DOLAN, P. The Effect of Nuclear Weapons. 3rd ed. USA: United States Department of Defence, 1977.
3. COOP, C. An Introduction to the Technical and Operational Aspects of the Electromagnetic Bomb. Canberra: RAAF Air Power Studies Centre Technical Reports, 1996.
4. TAYLOR, C. D., GIRI, D. V. High-Power Microwave Systems and Effects. Washington: Taylor and Francis, 1994.
5. BARKER, R. J., SCHAMILOGLU, E. High-Power Microwave Sources and Technologies. IEEE Press, 2002.
6. DRAZAN, L. The Chosen Problems of Directed Energy Weapons Radio Frequency and Microwave Design. Inaugural dissertation. Brno: University of Defence, 2008. 144 p. [in Czech].
7. ALGILBERS, L. L., GRISHNAEV, I., TKACH, Y. Magnetocumulative Generators. New York: Springer-Verlag, 2000.
8. DRAZAN, L., ZAJONC, J. Magneto-cumulative generator test results - version G3 and G4 (22.10.2002). APPM project technical report. Brno: Military Academy, 2002. [in Czech].
9. DRAZAN, L., ZAJONC, J. Magneto-Cumulative Generator Test Results, ver. G3 and G4 (26.11.2002). APPM project technical report. Brno: Military Academy, 2002. [in Czech].
10. DRAZAN, L., ZAJONC, J. Magneto-Cumulative Generator Test Results – ver. G3 (9.12.2002). APPM project technical report. Brno: Military Academy, 2002. [in Czech].
11. DRAZAN, L., ZAJONC, J. Magneto-Cumulative Generator Test Results – ver. G3 (7.1.2003). APPM project technical report. Brno: Military Academy, 2003. [in Czech].
12. DRAZAN, L., ZAJONC, J. Magneto-Cumulative Generator Optimisation Possibility. APPM project technical report. Brno: Military Academy, 2003. [in Czech].
13. MILLER, R., B. An Introduction to the Physics Intense Particle Beams. New York: Plenum Press, 1982.
14. BEZDEK, M., TECL, S., DRAZAN, L. Report Concerning the Vircator Research Results. Research report. Vyskov: VOP-026 Sternberk, 2005. [in Czech].
15. SUNKA, P. High Power Pulse Generation. Lectures collection. Prague: Academy of Sciences of the Czech Republic, Institute of Plasma Physics, 2004. [in Czech].
16. DRAZAN, L.,ZAJONC, J. Test of Pulse Forming Line and Design of Microwave Generator with Virtual Cathode. APPM project technical report. Brno: Military Academy, 2003. [in Czech].
17. DOSTAL, F., PLCH, Z. GENVLN - Measurement. Technical report. Vyskov: VOP 026 Sternberk, 2008. [in Czech].
18. DREXLER, P., FIALA, P. Methods for high power EM pulse measurement. Radioengineering, 2006, vol. 15, no. 4, p. 43-49.

Keywords: Electronic warfare, directed energy weapons microwave, high power microwave, magneto-cumulative generator, Marx generator, pulse forming line, vircator.

L. Burita [references] [full-text] [Download Citations]
Multilateral Interoperability Programme

The Multilateral Interoperability Programme (MIP) is a voluntary and independent activity in NATO environment by the participating nations and organizations. The MIP concept is based on data exchange in form of common exchange data model to achieve the international interoperability in command and control information systems (C2IS) of the tactical units. The article describes the basis of the MIP organizations, structure, planning and testing processes. The core of the MIP solution is the Information Exchange Data Model (IEDM). The Czech Armed Forces (CAF) MIP process implementation is mentioned. The MIP example is a part of university education process.

1. THE JOINT C3 INFORMATION EXCHANGE DATA MODEL. Germany, Greding: MIP community, 2007, 860 pp.
2. http://www.mip-site.org/.

Keywords: Interoperability, Command and Control Information System (C2IS), Multilateral Interoperability Programme (MIP), Joint Consultation Command and Control Information Exchange Data Model (JC3IEDM); data, model, test, CAF, NATO.

M. Varchola, M. Drutarovsky [references] [full-text] [Download Citations]
Embedded Platform for Automatic Testing and Optimizing of FPGA Based Cryptographic True Random Number Generators

This paper deals with an evaluation platform for cryptographic True Random Number Generators (TRNGs) based on the hardware implementation of statistical tests for FPGAs. It was developed in order to provide an automatic tool that helps to speed up the TRNG design process and can provide new insights on the TRNG behavior as it will be shown on a particular example in the paper. It enables to test sufficient statistical properties of various TRNG designs under various working conditions on the fly. Moreover, the tests are suitable to be embedded into cryptographic hardware products in order to recognize TRNG output of weak quality and thus increase its robustness and reliability. Tests are fully compatible with the FIPS 140 standard and are implemented by the VHDL language as an IP-Core for vendor independent FPGAs. A recent Flash based Actel Fusion FPGA was chosen for preliminary experiments. The Actel version of the tests possesses an interface to the Actel’s CoreMP7 softcore processor that is fully compatible with the industry standard ARM7TDMI. Moreover, identical tests suite was implemented to the Xilinx Virtex 2 and 5 in order to compare the performance of the proposed solution with the performance of already published one based on the same FPGAs. It was achieved 25% and 65% greater clock frequency respectively while consuming almost equal resources of the Xilinx FPGAs. On the top of it, the proposed FIPS 140 architecture is capable of processing one random bit per one clock cycle which results in 311.5 Mbps throughput for Virtex 5 FPGA.

1. MENEZES, J. A., OORSCHOT, P. C., VANSTONE, S. A. Handbook of Applied Cryptography. New York: CRC Press, 1997. [Online]. Available at: http://www.cacr.math.uwaterloo.ca/hac/.
2. MARKETTOS, A. T., MOORE, S. W. The frequency injection attack on ring-oscillator-based true random number generators. In Proceedings of Cryptographic Hardware and Embedded Systems. Lausanne (Switzerland), 2009, p. 317 - 331.
3. SCHINDLER, W. Random number generators for cryptographic applications. Cryptographic Engineering. Berlin: Springer, 2009.
4. SCHINDLER, W. Evaluation criteria for physical random number generators. Cryptographic Engineering. Berlin: Springer, 2009.
5. SUNAR, B. Random number generators for cryptography. Cryptographic Engineering. Berlin: Springer, 2009.
6. DAVIES, P. Flexibile security. In Thales e-Security, White Paper - Cryptography & Interoperability, 2003.
7. SCHINDLER, W. Efficient online tests for true random number generators. In Proceedings of Cryptographic Hardware and Embedded Systems. Paris (France), 2001, p. 103 - 117.
8. U.S. Department of Commerce / National Institute of Standards and Technology. Federal Information Processing Standards Publication FIPS PUB 140-1, 1994.
9. U.S. Department of Commerce / National Institute of Standards and Technology. Federal Information Processing Standards Publication FIPS PUB 140-2, 2001.
10. FISCHER, V. DRUTAROVSKY, M. True random number generator embedded in reconfigurable hardware. In Proceedings of Cryptographic Hardware and Embedded Systems. Redwood City (USA), 2002, p. 415 - 430.
11. GOLIC, J. New methods for digital generation and postprocessing of random data. In IEEE Transactions on Computers, 2006, vol. 55, no. 10, p. 1217 - 1229.
12. DRUTAROVSKY, M., VARCHOLA, M. Cryptographic system on a chip based on actel ARM7 soft-core with embedded true random number generator. In IEEE Workshop on Design and Diagnostics of Electronic Circuits and Systems. Bratislava (Slovakia), 2008, p. 164 - 169.
13. VANCAK, O. Implementation of the Statistical Randomness Tests for Cryptographic Applications in FPGA Devices. Master Thesis. Technical University of Kosice, 2009.
14. HASEGAWA, A., KIM, S. J., UMENO, K., KITAMACHI, N. IP core of statistical test suite of FIPS 140-2. Design & Reuse. [Online]. Cited 2009-10-16. Available at: http://www.design-reuse.com/articles/7946/ip-core-of-statistical-test-suite-of-fips-140-2.html .
15. SUNAR, B., MARTIN, W. J., STINSON, D. R. A provably secure true random number generator with built-in tolerance to active attacks. IEEE Transactions on Computers, 2007, vol. 56, no. 1, p. 109 - 119.
16. SUNAR, B. Response to Dichtl’s Criticism. 2008.
17. SCHELLENKES, D., PRENEEL, B., VERBAUWHEDE, I. FPGA Vendor agnostic true random number generator. In Proceedings of International Conference Field Programmable Logic and Applications. Madrid (Spain), 2006.
18. DICHTL, M. Scrutinizing the assumptions used in the security proof of a true random generator. IEEE Transactions on Computers, 2007.
19. VASYLTSOV, I., HAMBARDZUMYAN, E., KIM, Y. S., KARPINSKYY, B. Fast digital TRNG based on metastable ring oscillator. In Proceedings of Cryptographic Hardware and Embedded Systems. Washington DC (USA), 2008, p. 164 - 180.
20. WOLD, K. TAN, C. H. Analysis and enhancement of random number generator in FPGA based on oscillator rings. In International Conference on Reconfigurable Computing and FPGAs. Cancun (Mexixo), 2008, p. 385 - 390.
21. KILLMANN, W., SCHINDLER, W. Functionality classes and eval-uation methodology for true (physical) random number generators. AIS 31: Application Notes and Interpretation of the Scheme (AIS), 2001.
22. RUKHIN, A., et al. A statistical test suit for random and pseudorandom number generators for cryptographic applications. NIST Special Publication 800-22, 2001.
23. VARCHOLA, M., DRUTAROVSKY, M., FOUQUET, R., FISCHER, V. Hardware platform for testing performance of TRNGs embedded in actel fusion FPGA. In Proceedings of the 18th International Conference Radioelektronika. Prague (Czechia), 2008, p. 145 - 148.
24. ROZIC, V., VERBAUWHEDE, I. Random numbers generation: Investigation of narrow transitions suppression on FPGA. Proceedings of International Conference Field Programmable Logic and Applications. Prague (Czechia), 2009.
25. FISHER, V., BERNARD, F., BOCHARD, N., VARCHOLA, M. Enhancing security of ring oscillator-based RNG implemented in FPGA. In Proceedings of International Conference Field Programmable Logic and Applications. Heidelberg (Germany), 2008, p. 245 - 250.
26. VALTCHANOV, B., AUBERT, A., BERNARD, F., FISCHER, V. Modeling and observing the jitter in ring oscillators implemented in FPGAs. In IEEE Workshop on Design and Diagnostics of Electronic Circuits and Systems. Bratislava (Slovakia), 2008, p. 158 - 163.
27. VARCHOLA, M., DRUTAROVSKY, M. New FPGA based TRNG principle using transition effect with built-in malfunction detection. In International Workshop on Cryptographic Architectures Embedded in Reconfigurable Devices - CryptArchi. Prague (Czechia), 2009, p. 150-155.
28. SANTORO, R., SENTIEYS, O., ROY, S. On-Line monitoring of random number generators for embedded security. In IEEE International Symposium on Circuits and Systems. Taipei (Taiwan), 2009, p. 3050 - 3053.

Keywords: TRNG, on-chip randomness tests, FIPS 140, FPGA

F. Dvorak, J. Maschke, C. Vlcek [references] [full-text] [Download Citations]
Utilization of Birefringent Fiber as Sensor of Temperature Field Disturbance

The paper deals with utilization of induced birefringence sensitivity to temperature field in birefringent optical fibers. The propagating optical wave and optical fibers are described by means of coherency and Jones matrices, which are decomposed into unitary matrix and spin matrices. The development of polarization caused by temperature field is interpreted on the Poincare sphere by means of MATLAB® environment. The temperature sensitivity of Panda and bow-tie fiber has been measured for circular polarization excitation. Curves of intensity fluctuation caused by the temperature dependence are presented.

1. ZHANG, Ζ., LIT, J. W. Y. Temperature sensitivity measurement birefringent polarization-maintaining fibres. SPIE vol. 1580 Fiber Optic Components and Reliability, 1991.
2. DVORAK, F., MASCHKE, J., VLCEK, C. Study of time fluctuation of polarization of polarization preserving fibers. In Proceedings of 19th IMEKO World Congress. Lisbon (Portugal), 2009, p. 80 - 83.
3. CUBIAN, D. P., ARCE-DIEGO, J. L., FREY, R. Application of the Quaternions theory to the analysis of the semimagnetic semiconductor microcavity. SPIE vol.5036 Photonics, Devices, and Systems II. Prague (Czech Republic), 2002, p. 511 - 517.
4. KORN, G. A., KORN, T. M. Mathematical Handbook for Scientists and Engineers. McGraw-Hill, 1968.
5. JONES, R. C. A new calculus for the treatment of optical systems. I. Description and discussion of the calculus. J. Opt. Soc. Am., 1941, 31, p. 488 - 493.
6. SHURCLIFF, W. A. Polarized Light, Production and Use. Cambridge, Massachusetts: Harvard University Press, 1962.
7. TALPA, M. Automated measurement with table calculator Microsoft Excel. In Proceedings of the Conference STO-7. Brno (Czech Republic), 1999, p. 235 - 238 (in Czech).

Keywords: Induced birefringence, temperature dependence, birefringence sensitivity, beat length, Jones matrix, coherency matrix, spin matrices, Poincare sphere, temperature sensor.

K. Malinka, P. Hanacek, D. Cvrcek [references] [full-text] [Download Citations]
Analyses of Real Email Traffic Properties

In this paper, we perform an empirical analysis of email traffic logs obtained from a large university to better understand its impact on the effectiveness and efficiency of anonymous mix remailers. We analyzed data containing records of almost 790,000 emails sent over a period of forty days – the largest dataset we are aware of. The initial analysis of data is followed by an exploration of how variance in message arrival time and size impact the anonymity and efficiency provided by timed and threshold mixes, respectively. The analysis results are subsequently explored for their possible impact on traffic analysis.

1. BERTHOLD, O., FEDERRATH, H., KOPSELL, S. Web MIXes: A System for anonymous and unobservable internet access. In Workshop on Design Issues in Anonymity and Unobservability, 2000, p. 115--129.
2. CHAUM, D. Untraceable electronic mail, return addresses, and digital pseudonyms. Communications of ACM, 1981, vol. 24, no. 2, p. 84-88.
3. DANEZIS, G. Stastistical disclosure attacks: Traffic confirmation in open environments. In Proceedings of Security and Privacy in the Age of Uncertainty, (SEC2003), Gritzalis, Vimercati, Samarati, and Katsikas (Eds.). Athens: Kluwer, May 2003, p. 421 - 426.
4. DANEZIS, G. The traffic analysis of continuous-time mixes. In Proceedings of Privacy Enhancing Technologies Workshop (PET 2004). Springer-Verlag, LNCS 3424, 2004.
5. DANEZIS, G., DINGLEDINE, R., MATHEWSON, N. Mixminion: Design of a type III anonymous remailer protocol. In Proceedings of 2003 Symposium on Security and Privacy. IEEE Computer Society, May 11-14, 2003, p. 2-15.
6. DIAZ, C., SASSAMAN, L., DEWITTE, E. Comparison between two practical mix designs. In Computer Security (ESORICS'04), P. Samarati et al. (Eds.), Springer-Verlag, LNCS 3193, p. 141 - 159, 2004.
7. DIAZ, C., SEYS, S., CLAESSENS, J., PRENEEL, B. Towards measuring anonymity. In Proceedings of Privacy Enhancing Technologies Workshop (PET 2002). Springer-Verlag, LNCS 2482, 2002.
8. DINGLEDINE, R., MATHEWSON, N., SYVERSON, P. F. Tor: The second-generation onion router. In USENIX Security Symposium, 2004, p. 303--320.
9. FREEDMAN, M. J., MORRIS, R. A peer-to-peer anonymizing network layer. In SIGSAC: 9th ACM Conference on Computer and Communications Security. ACM SIGSAC, 2002.
10. KESDOGAN, D., EGNER, J., BUSCHKES, R. Stop-and-Go MIXes Providing Probabilistic Anonymity in an Open System. In Springer-Verlag, LNCS 1525, p. 83--98, 1998.
11. MATHEWSON, N., DINGLEDINE, R. Practical traffic analysis: extending and resisting statistical disclosure. In Proceedings of Privacy Enhancing Technologies Workshop (PET 2004), LNCS 3424, 2004.
12. NEWMAN, R. E., MOSKOWITZ, I. S., SYVERSON, P., SERJANTOV, A. Metrics for traffic analysis prevention. In Proceedings of Privacy Enhancing Technologies workshop (PET 2003). Springer-Verlag, LNCS 2760, 2003.
13. PAXSON, V., FLOYD, S. Wide-Area Traffic: The failure of Poisson modeling. IEEE/ACM Transactions on Networking, 1995, vol. 3, no. 3, p. 226 - 244.
14. RACKOFF, C., SIMON, D. R. Cryptographic defense against traffic analysis. In Proceedings of {ACM} Symposium on Theory of Computing, 1993, p. 672 - 681.
15. SERJANTOV, A., DANEZIS, G. Towards an information theoretic metric for anonymity. In Proceedings of Privacy Enhancing Technologies Workshop (PET 2002). Springer-Verlag, LNCS 2482, 2002.
16. SERJANTOV, A., DINGLEDINE, R., SYVERSON, P., PETITCOLAS, F. A. P. From a Trickle to a Flood: Active Attacks on Several Mix Types. In Information Hiding 2002 (IH 2002). Springer-Verlag, LNCS 2578, 2002, p. 36 - 52.

Keywords: SMTP, email traffic, mixing, anonymity, social networks.

V. Bolom, J. Ingerle, P. Sovka [references] [full-text] [Download Citations]
Derivation of Criterion Suitable for Evaluation of Multichannel Noise Reduction Systems for Speech Processing

This paper deals with the theoretical derivation of the Noise Reduction criterion suitable for evaluation of multichannel noise reduction system performance. This criterion is suitable for noise suppression assessment and thus serves as an important step in the development of noise reduction systems. Noise reduction is evaluated in dependence on spatial coherence. The derivations are made for five basic multichannel systems, Delay and sum beamformer, Beamformer with adaptive postprocessing, Generalized sidelobe canceller, Linearly constrained beamformer, and Modified coherence filter.

1. BITZER, J., SIMMER, K. U., KAMMEYER, K.-D. Theoretical noise reduction limits of the generalized sidelobe canceller (GSC) for speech enhancement. In International Conference on Acoustics, Speech, and Signal Processing ICASSP '99. Vol. 5. Phoenix (USA), 1999. p. 2965–2968.
2. BOUQUIN, R. L. Enhancement of noisy speech signals: application to mobile radio communications. Speech Communication, 1996, vol. 18, no. 1, p. 3–19.
3. CRON, B. F., SHERMAN, C. H. Spatial-correlation functions for various noise models. Journal of Acoustic Society of America, 1962, vol. 34, no. 11.
4. FISCHER, S., SIMMER, K. U. Beamforming microphone arrays for speech acquisition in noisy environments. Speech Communication, 1996, vol. 20, p. 215–227.
5. FROST, O. L. An algorithm for linearly constrained adaptive array processing. In IEEE, 1972, vol. 60, p. 926–934.
6. GRIFFITHS, L. J., CHARLES, W. J. An alternative approach to linearly constrained adaptive beamforming. IEEE Transaction on Antenas and Propagation,1982, vol. AP-30, no. 1.
7. INGERLE, J. Methods of Speech Signal Enhancement Combining Beamforming and Postfiltration. PhD thesis, Prague: FEL, Czech Technical University, 2003. In Czech.
8. MAHMOUDI, D., DRYGAJLO, A. Combined Wiener and coherence filtering in wavelet domain for microphone array speech enhancement. In Proceedings of the 1998 International Conference on Acoustics, Speech and Signal Processing. Vol. 1. Seattle (USA), 1998, vol. 1, p. 385–388.
9. MARRO, C., MAHIEUX, Y., SIMMER, K. U. Analysis of noise reduction and dereverberation techniques based on microphone arrays with postfiltering. IEEE Transactions on Speech and Audio Processing, 1998, vol. 6, no. 3, p. 240-259.
10. MEYER, J., SIMMER, K. U. Multi-channel speech enhancement in a car environment using Wiener filtering and spectral subtraction. InInternational Conference on Acoustics, Speech, and Signal Processing ICASSP ’97. Vol. 2. Munich (Germany), 1997, p. 1167–1170.
11. RAFAELY, B. Spatial-temporal correlation of a diffuse sound field. The Journal of the Acoustical Society of America, 2000, vol. 107, no. 6, p. 3254–3258.
12. SIMMER, K. U., BITZER, J., MARRO, C. Post-filtering techniques Microphone Arrays. Berlin: Springer, 2001, p. 39–57.
13. SIMMER, K. U., WASILJEFF, A. Adaptive microphone arrays for noise suppression in the frequency domain. In COST-229 Workshop on Adaptive Algorithms in Communications. Bordeaux (France), 1992, p. 185–194.
14. SOVKA, P., POLLAK, P. Chosen Methods of Digital Signal Processing. Prague: CTU Publishing House, 2003. In Czech.
15. UHLIR, J., SOVKA, P. Digital Signal Processing. Prague: CTU Publishing House, 2002. In Czech.
16. VAN VEEN, B. D., BUCKLEY, K. M. Beamforming: A versatile approach to spatial filtering. IEEE ASSP Magazine, 1988, p. 4–24.
17. STRUPL, M., SOVKA, P. Analysis and simulation of frost's beamformer. Radioengineering, 2003, vol. 12, no. 3, pp. 1–9.
18. WIDROW, B., STEARNS, S. D. Adaptive Signal Processing. Prentice-Hall, 1985.
19. ZELINSKI, R. A microphone array with adaptive postfiltering for noise reduction in reverberant rooms. In International Conference of Acoustic Speech Signal Processing. New York (USA), 1988, p. 2578–2581.

Keywords: Beamforming, microphone arrays, speech enhancement, noise reduction.

J. Nouza, J. Silovsky [references] [full-text] [Download Citations]
Fast Keyword Spotting in Telephone Speech

In the paper, we present a system designed for detecting keywords in telephone speech. We focus not only on achieving high accuracy but also on very short processing time. The keyword spotting system can run in three modes: a) an off-line mode requiring less than 0.1xRT, b) an on-line mode with minimum (2 s) latency, and c) a repeated spotting mode, in which pre-computed values allow for additional acceleration. Its performance is evaluated on recordings of Czech spontaneous telephone speech using rather large and complex keyword lists.

1. ALON, G. Key-word spotting – The base technology for speech analytics. Natural Speech Communications, July 2005.
2. SZOKE, I., SCHWARZ, P., MATEJKA, P., BURGET, L., FAPSO, M., KARAFIAT, M., CERNOCKY, J. Comparison of keyword spotting approaches for informal continuous speech. In Proc. of Interspeech 2005. Lisbon (Portugal), Sept. 2005, p. 633–636.
3. NOUZA, J., ZDANSKY, J., CERVA, P., KOLORENC, J. A System for information retrieval from large records of Czech spoken data. Lecture Notes in Computer Science. LNAI 4188. Berlin, Heidelberg : Springer-Verlag, 2006, pp. 485-492.
4. KNILL, K. M., YOUNG, S. J. Fast implementation methods for Viterbi-based word-spotting. In Proc. of ICASSP 1996. Atlanta (USA), 1996, p. 522-525.
5. NOUZA, J., ZDANSKY, J., CERVA, P., KOLORENC, J. Continual on-line monitoring of Czech spoken broadcast programs. In Proc. of Interspeech 2006. Pittsburgh (USA), 2006, p. 1650-1653.
6. NOUZA, J., CERVA, P., ZDANSKY, J. Very large vocabulary voice dictation for mobile. In Proc. of Interspeech 2009. Brighton (UK), 2009.
7. KUMAR, N. Investigation of silicon-auditory models and generalization of linear discriminant analysis for improved speech recognition. Ph.D. dissertation, John Hopkins University, Baltimore, 1997.
8. GALES, M. J. F. Semi-tied covariance matrices for hidden Markov models. IEEE Transactions Speech and Audio Processing, 1999, vol. 7, no. 3, pp. 272-281.
9. HERMANSKY, H. Perceptual linear predictive (PLP) analysis of speech. J. Acoust. Soc. Am., Apr. 1990, vol. 87, no. 4, pp. 1738 to 1752.

Keywords: Speech processing, keyword decoder, HLDA transformation. spotting, speech

F. Grezl, J. Cernocky [references] [full-text] [Download Citations]
Audio Surveillance through Known Event Classification

The way of audio surveillance through known event classification is presented introducing simple yet efficient framework. The use of the proposed system for unknown event detection is also suggested and evaluated. Further, a specific audio event is detected with use of audio classification, which helps the detection to focus on a signal of specific behavior. Thus it is shown that the system can be used in several applications.

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Keywords: Sound classification, event detection, audio surveillance.