# September 2006, Volume 15, Number 3

**J. Lacik, Z. Raida**
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Modeling Microwave Structures in Time Domain Using Laguerre Polynomials

The paper is focused on time domain modeling of microwave structures by the method of moments. Two alternative schemes with weighted Laguerre polynomials are presented. Thanks to their properties, these schemes are free of late time oscillations.

Further, the paper is aimed to effective and accurate evaluation of Green\'s functions integrals within these schemes. For this evaluation, a first- and second-order polynomial approximation is developed.

The last part of the paper deals with modeling microstrip structures in the time domain. Conditions of impedance matching are derived, and the proposed approach is verified by modeling a microstrip filter.

- RAO, S. M. Time Domain Electromagnetics. London: Academic Press, 1999.
- RAO, S. M., SARKAR, T. K. Numerical solution of time domain integral equations for arbitrarily shaped conductor/dielectric composites bodies. IEEE Transactions on Antennas and Propagation. 2002, vol. 50, no. 12, p. 1831-1837.
- LACIK, J., RAIDA, Z., MOTL, M. TD-EFIE with 3-point backward difference and stability investigation. WSEAS Transactions on Computers. 2004, vol. 3, no. 6, p. 1877-1881.
- CHUNG., S., SARKAR, T. K., JUNG, B. H., SALZAR-PALMA, M., JI, Z., JANG, S., KIM, K. Solution of time domain electric field integral equation using the Laguerre polynomials. IEEE Transactions on Antennas and Propagation. 2004, vol. 52, no. 9, p. 2319-2328.
- RAO, S. M., WILTON, D. R., GLISSON, A. W. Electromagnetic scattering by surfaces of arbitrary shape. IEEE Transactions on Antennas and Propagation. 1982, vol. 30, no. 5, p. 409-418.
- POULARKIS, A. D. The Transforms and Applications Handbook. Piscataway: IEEE Press, 1996.
- LACIK, J., RAIDA, Z. Transient analysis of scatterers and antennas: Laguerre polynomials scheme with improved efficiency. In Proc. of the International Conference on Electromagnetics in Advanced Applications ICEAA 2005. Turin (Italy): Polytecnico di Torino, 2005, p. 257-260.
- MAKAROV, S. MoM antenna simulations with Matlab: RWG basis functions. IEEE Antennas and Propagation Magazine. 2001, vol. 43, no. 5, p. 100-107.
- LACIK, J. Modelling of antennas in the time domain using Laguerre polynomials. In Proceedings of STUDENT EEICT 2005. Brno: Brno University of Technology, 2005, p. 426-430.
- WILTON, D. R., RAO, S. M., ALLEN, W. Potential integrals of uniform and linear source distributions on polygonal and polyhedral domains. IEEE Transactions on Antennas and Propagation. 1984, vol. 32, no. 3, p. 276-281.
- EIBERT, T. F., HANSEN, V. On the calculation of potential integrals for linear source distributions on triangular domains. IEEE Transactions on Antennas and Propagation. 1995, vol. 43, no. 12, p. 1499-1502.
- MOSIG, J., R. Analytical and numerical techniques in the Green's function treatment of microstrip antennas and scatterers. Proceedings of IEE. 1983, vol. 130, no.2, p. 175-182.
- POZAR, D. M. Microwave Engineering. New York: J. Wiley and Sons, 2005.

Keywords: Time domain analysis, method of moments, Laguerre polynomials, microstrip structures

**L. Merad, F. T. Bendimerad, S. M. Meriah**
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Controlled Random Search Optimization for Linear Antenna Arrays

An optimization problem for designing nonuniformly spaced, linear antenna\'s arrays is formulated and solved by means of a controlled random search algorithm.

The proposed iterative method aims at a linear array and the optimization of element positions and excitations coefficients by minimizing the side-lobes level and respecting a beam pattern shape. Selected examples are included, which demonstrate the effectiveness and the design flexibility of the proposed method in the framework of the electromagnetic synthesis of linear antenna arrays.

- YANG, S., BENG GAN, Y., QING, A. Antenna-array pattern nulling using a differential evolution algorithm. International Journal on RF and Microwave.2004, vol. CAE 14, p. 57-63.
- LUE, W. C., HSU, F. Use of B-spline curves and genetic algorithms to reduce the sidelobe level in array-patterns. Microwave and Optical Technology Letters, 2003, vol. 38, no. 4, p. 308-311.
- BALANIS, C. Antenna Theory - Analysis and Design. New York: Wiley, 1982.
- YAN, K., LU, Y. Sidelobe reduction in array-pattern synthesis using genetic algorithms. IEEE Transactions on Antennas and Propagation, 1997, vol. 45, no. 7, p. 1117-1122.
- AKDAGLI, A., GUNEY, K. Shaped beam pattern synthesis of equally and unequally spaced linear antenna arrays using modified tabu search algorithm. Microwave and Optical Technology Letters, 2003, vol. 36, No. 1, p. 16-20.
- ALI, M. Some Modified Global Optimization Algorithms with Applications. Loughborough University of Technology, PH.D Thesis, 1994.
- ALI, M. M., STOREY, C., TORN, A. Application of some stochastic global optimization algorithms to practical problems. Journal of Optimization Theory and Applications, 1997, vol. 95, no. 3, p. 545 to 563.
- PRICE, W.L. Global optimization by controlled random search. Journal of Optimization Theory and Applications, 1983, vol. 40, p. 333-348.

Keywords: Antenna array, pattern shape, synthesis, optimization, controlled random search

**P. Piksa, M. Mazanek**
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A Self-Complementary 1.2 to 40 GHz Spiral Antenna with Impedance Matching

This paper describes a design of the Self- Complementary Spiral Antenna (SCSA) which consists of a spiral antenna and a wideband impedance transformer. The spiral antenna and the transformer are designed separately due to computing demands. New knowledge about current distribution on the spiral antenna and influence of higher numbers of wavelength in circumference is presented. The novel transition between feeding and radiating antenna structure are optimized in the frequency range 1.2 to 40 GHz. The meaning of the transition in the paper includes the impedance as well as the geometry transforming of the structure. The antenna is suitable for wideband illuminating of a parabolic reflector due to relatively constant phase center and radiation pattern with frequency.

- MUSHIAKE, Y. Self-complementary antennas. IEEE Trans. Anten-nas Propagat. December 1992, vol. 34, p. 23 - 29.
- DYSON, John D. The equiangular spiral antenna. IRE Trans. An-tennas Propagat. April 1959, vol. 7, p. 181 - 187.
- RUMSEY, V. H. Frequency independent antennas. 1957 IRE Na-tional Convention Record. March 1957, p. 114 - 118.
- MISRA, D.K. Radio-frequency and microwave communication circuits: analysis and design. John Wiley & Sons, 2001, p. 189 - 242, ISBN 0-471-41253-8.
- NGUYEN, C. Analysis Methods for RF, Microwave, and Millime-ter-Wave Planar Transmission Line Structures. John Wiley & Sons, 2000, p. 63 - 84, ISBN 0-471-01750-7.
- PIKSA, P. An extending of a slot-field in the plane self-complementary spiral antenna. In Proceedings of the 13th Conference on Mi-crowave Techniques - COMITE 2005. Prague, 2005, p. 255-258,, ISBN 80-86582-16-7.
- http://www.zeland.com
- http://www.mathworks.com
- http://qucs.sourceforge.net/docs.html - Technical documentation.

Keywords: Spiral antenna, ultra wide-band, UWB, circular polarization, planar, self-complementary structure, current distribution, transition, impedance transformer, impedance matching, s-parameters renormalizing

**T. Bachorec, J. Dedkova**
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Image Reconstruction Based on Deterministic and Heuristic Approach

The aim of this paper is to provide a survey of the recent development in new algorithms and techniques to solve the electrical impedance tomography (EIT) inverse problem. The EIT problem is nonlinear and ill-posed. The modified Newton-Raphson method with the Tikhonov regularization and the differential evolution algorithm are used to obtain high-quality reconstruction in EIT problems. Numerical results of the reconstruction based on both deterministic and heuristic methods are presented and compared. Finally, we provide recommendations of solutions of still open problems in this field.

- CHENEY, M., ISAACSON, D., NEWELL, J., C. Electrical impedance tomography. SIAM Rev., vol. 41, no. 1, 1999, p. 85-101.
- SOMERSALO, E., CHENEY, M., ISAACSON, D. Existence and uniqueness for electrode models for electric current computed tomography. SIAM J. Appl. Math., vol. 52, 1992, p. 1023-1040.
- VAUHKONEN, M., VADASZ, D., KARJALAINEN, P. A., SOMERSALO, E., KAIPIO, J. P. Tikhonov regularization and prior information in electrical impedance tomography. IEEE Trans. Med. Eng., 1998, vol. 17, p. 285-293.
- BRANDSTATTER, B. Jacobian calculation for electrical impedance tomography based on the reciprocity principle. IEEE Transaction on Magnetics, 2003, vol. 39, no. 3, p.1309-1312.
- YORKEY, T. J., WEBSTER, J. G., TOMKINS, W. J. Comparing reconstruction algorithms for electrical impedance tomography. IEEE Trans. Biomed. Eng., 1987, vol. 34, p. 843-852.
- RAO, L., HE, R., WANG, Y., YAN, W., BAI, J., YE, D. An efficient improvement of modified Newton-Raphson algorithm for electrical impedance tomography. IEEE Transaction on Magnetics, 1999, vol. 35, p. 1562-1565.
- OLMI, R., BINI, M.,PRIORI, S. A genetic algorithm approach to image reconstruction in electrical impedance tomography. IEEE Trans. Evol. Comp., 2000, vol. 4, p. 83-88.
- MICHALEWICZ, Z. Genetic algorithms+Data Structure=Evolution Programs. 2nd ed. Springer Verlag Berlin, 1994.
- BORSIC, A. Regularization methods for imaging from electrical measurement. PhD. Thesis, Oxford Brookes University, 2002.
- BURGER, M. A level set method for inverse problems, Inverse Problems 17, 2001, p. 1327-1356.

Keywords: Spiral antenna, ultra wide-band, UWB, circular polarization, planar, self-complementary structure, current distribution, transition, impedance transformer, impedance matching, s-parameters renormalizing

**J. Bicak, J. Hospodka**
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Design of Dual Bandpass and Bandreject LC Ladder Filters

This paper deals with the design of two-passband bandpass and two-stopband bandreject LC ladder filters. The design method is based on the special dual frequency transformation that transforms normalized lowpass to either bandpass with two passbands or to bandreject with two stopbands that are specified by four cutoff frequencies. The paper shows analytical solution relating these four cutoff frequencies to parameters of dual frequency transformation. It enables a direct computation of dual band LC filter elements from a normalized lowpass filter by means of simple relations. These relations have been implemented in the mathematical program Maple (TM) as new user functions. They are supposed to be used as an enhancement of Syntfil package which is intended for analog filter design in program Maple. Specific application is shown on an example of the two-passband bandpass LC filter design.

- DAVIDEK, V., LAIPERT, M., VLCEK, M. Analogue and Digital Filters. 2nd edition. Praha: CTU Publishing House, 2004. (in Czech)
- OKSMAN, V. Standard VDSL Technology. Overview of European (ETSI), North American (T1E1.4) and International (ITU-T) VDSL standard development. Broadcom Corporation, July 2001, URL: http://www.ieee802.org
- TICHA, D., MARTINEK, P. OTA-C lowpass design using evolutionary algorithms. In Proceedings of the European Conference on Circuit Theory and Design, ECCTD'05. Cork: University College Cork, 2005, vol. 2, p. 197-200. ISBN 0-7803-9066-0.
- ZISKA, P., LAIPERT, M.: Analog group delay equalizers design based on evolutionary algorithm. Radioengineering. 2006, vol. 15, no.1
- HOSPODKA, J., BICAK, J. New features of Syntfil package for electric filters design. In Proceedings of Maple Conference 2005. Waterloo (Canada): Maplesoft, p. 36-44. ISBN 1-894511-85-9.
- HOSPODKA, J., BICAK, J.: WWW pages of Syntfil pages, URL: http://syntfil.feld.cvut.cz
- Syntfil package is sold through the Maplesoft Web site as part of the MapleConnect program. URL: http://www.maplesoft.com

Keywords: Frequency transformation, two-passbands bandpass filter, two-stopbands bandreject filter, Syntfil package

**J. Hospodka**
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Optimization of Dynamic Range of Cascade Filter Realization

This paper deals with a dynamic range optimization procedure for active filters based on the cascade realization. Dynamic characteristics of the cascade filter depend on many factors, mainly on pole-zero pairing, section ordering and gain assignment. Just the procedure for an optimal gain assignment for particular biquadratic sections is discussed in this paper. The input parameters of the procedure are parameters of particular biquads i.e. pole frequency ω_{0}, quality factor Q, eventually zero frequency ω_{n} for elliptic section and the transfer function type of the section. The gain is distributed so that output signal limitation of particular biquads occurs for the same level of the filter input signal. The procedure is versatile - can be used for analog as well as for digital filters with the cascade structure. The presented algorithm is fully universal (does not suppose any simplification). It has been used in Syntfil package for the filter design in the mathematical program Maple.

- SCHAUMANN, R., GHAUSI, M. S., LAKER, K. R. Design of Analog Filters. Passive, Active RC and Switched Capacitor. Englewood Cliffs: Prentice Hall, 1990.
- HOSPODKA, J. Cascade realization of electrical filters using SYNTFIL package. In Digital Communications '03. Zilina: EDIS-vydavatelstvo ZU. 2003, vol. 1, p. 25-29. ISBN 80-8070-165-2.
- HAJEK K., SEDLACEK J. Frequency-Selection Filters. Praha: Technical literature BEN, 2002. ISBN 80-7300-023-7. In Czech.
- HRUBY J., NOVAK M.: Microelectronic RC Filters with Amplifiers. Akademia/Praha 1976. (published in Czech).
- HOSPODKA, J., BICAK, J. Syntfil - synthesis of electric filters in Maple. In MSW 2004 [CD-ROM]. Waterloo, ON: Maplesoft, a division of Waterloo Maple Inc., 2004.
- HOSPODKA, J., BICAK, J. New features of Syntfil package for electric filters design. In Proceedings of Maple Conference 2005, Waterloo, ON: Maplesoft, p. 36-44. ISBN 1-894511-85-9.
- HOSPODKA, J., BICAK, J. WWW pages of Syntfil package, URL: http://syntfil.feld.cvut.cz/.

Keywords: Gain assignment, cascade filter realization, dynamic range optimization

**T. Kratochvil**
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Influence of the FEC Channel Coding on Error Rates and Picture Quality in DVB Baseband Transmission

The paper deals with the component analysis of DTV (Digital Television) and DVB (Digital Video Broadcasting) baseband channel coding. Used FEC (Forward Error Correction) error-protection codes principles are shortly outlined and the simulation model applied in Matlab is presented. Results of achieved bit and symbol error rates and corresponding picture quality evaluation analysis are presented, including the evaluation of influence of the channel coding on transmitted RGB images and their noise rates related to MOS (Mean Opinion Score). Conclusion of the paper contains comparison of DVB channel codes efficiency.

- RIEMERS, U. Digital Video Broadcasting. The Family of International Standards for Digital Television (second edition). Springer, 2004.
- WICKER, S. B., BHARGAVA, V. G. Reed Solomon Codes and Their Applications. IEEE Press, 1994.
- JOHANNESSON, R., ZIGANGIROV, K. S. Fundamentals of Convolution Coding. IEEE Press, 1999.
- KRATOCHVIL, T. Utilization of Matlab for digital image transmission simulation using the DVB error correction codes. Proceedings of Czech and Slovak Technical Universities and URSI Committees Radioengineering, vol. 12, no. 4, 2003.
- ITU. Methodology for the Subjective Assessment of the Quality of Television Pictures, ITU-R BT.500-11, 2002.
- MRAK, M., GRGIC, S., GRGIC, M. Picture quality measures in image compression systems. Proceedings of the Eurocon 2003 Conference, Ljubljana (Slovenia), 2003, p. 233-237.
- KRATOCHVIL, T. Transmission Distortion Analysis of Digital Video Signals. PhD Thesis, Brno University of Technology, 2006 (in Czech).

Keywords: Digital television, channel coding, forward error correction, error rates, picture quality, MOS

**J. Silovsky, J. Nouza**
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Speech, Speaker and Speaker\'s Gender Identification in Automatically Processed Broadcast Stream

This paper presents a set of techniques for classification of audiosegments in a system for automatic transcription of broadcast programs. The task consists in deciding a) whether the segment is to be labeled as speech or a non-speech one, and in the former case, b) whether the talking person is one of the speakers in the database, and if not, c) which gender the speaker belongs to. The result of the classification is used to extend the information provided by the transcription system and also to enhance the performance of the speech recognition module. Like the most of the state-of-the-art speaker recognition systems, the proposed one is based on Gaussian Mixture Models (GMM). As the number of the database speakers can be large, we introduce a technique that speeds up the identification process in significant way. Furthermore, we compare several approaches to the estimation of GMM parameters. Finally, we present the results achieved in classification of 230 minutes of real broadcast data.

- ZDANSKY, J., NOUZA, J. Detection of acoustic change-points in audio records via global BIC maximization and dynamic program-ming. In Interspeech 2005. Lisboa (Portugal), 2005 p. 669-672. ISSN 1018-4074.
- SILOVSKY, J. Speaker Recognition in Broadcast Streams. Diploma thesis (in Czech). Liberec: TU of Liberec, 2006.
- REYNOLDS, D.A., QUATIERI, T.F., DUNN, R.B. Speaker verifi-cation using adapted Gaussian mixture models. Digital Signal Proc-essing 10, 19-41, 2000.
- PADRTA, A., RADOVA, V. On the background model construction for speaker verification using GMM. Text, Speech and Dialogue TSD 2004. Lecture Notes in Artificial Intelligence 3206. Springer-Verlag: Berlin, Heidelberg, 2004, p. 425-432. ISBN 3-540-23049-1, ISSN 0302-9743.
- MARIETHOZ, J., BENGIO, S. An Alternative to Silence Removal for Text-Independent Speaker Verification. IDIAP-RR 03-51, 2003.
- NARAYANASWAMY, B. Improved Text-Independent Speaker Recognition using Gaussian Mixture Probabilities. A Report in Candidacy for the Degree of Master of Science. Carnegie Mellon University, May 2005.
- CERVA, P., NOUZA, J., SILOVSKY, J. Two-step unsupervised speaker adaptation based on speaker and gender recognition and HMM combination. In Interspeech 2006. Pittsburg (USA): 2006.

Keywords: Speaker recognition, Gaussian mixture models, broadcast speech transcription

**R. Marsalek**
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On the Reduced Complexity Interleaving Method for OFDM PAPR Reduction

Many methods for OFDM Peak to Average Power Ratio reduction have been proposed during approximately last ten years. There are nowadays many research efforts on PAPR reduction methods with reduced computational complexity. The method presented in this paper is based on adaptive symbol selection principle, with several replicas of signal created using set of interleavers incorporated inside an IFFT block at OFDM transmitter. This paper also discusses some practical aspects of this method - influence of zero padding and pilot positions.

- TELLADO, J. Multicarrier Modulation with Low PAR Applications to DSL and Wireless, Kluwer Academic Publishers, 2000.
- MARSALEK, R., FEDRA, Z. Reduced complexity adaptive symbol selection method for OFDM PAPR reduction. In Proceedings of 7th Nordic Conference NORSIG 2006, June 2006, Reykjavik, Iceland.
- OCHIAI, H., IMAI, H. Performance of the deliberate clipping with adaptive symbol selection for strictly band-limited OFDM systems. IEEE Journal on Selected Areas in Communications, 2000, vol. 18, no. 11, p. 2270-2277.
- HAN, S.H., LEE, J.H. PAPR Reduction of OFDM signals using a reduced complexity PTS technique. IEEE Signal Processing Letters, 2004, vol. 11, no. 11, p. 887-890.
- LIM, D.-W., NO, J.-S., LIM, CH.-W, CHUNG, H. A new SLM OFDM scheme with low complexity for PAPR reduction. IEEE Signal Processing Letters, 2005, vol. 12, no. 2, p. 93-96.
- INGLE, V.K., PROAKIS, J.G. Digital Signal Processing using MATLAB, Brooks/ Cole publishing, 2000.
- IEEE Std 802.11a-1999(R2003), Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) specifications.
- VAN NEE, R., PRASAD, R. OFDM for Wireless Multimedia Communications, Artech House Publishers, 2000.

Keywords: OFDM, PAPR reduction, multicarrier modulations

**V. Ricny**
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Compression Standard MPEG-4 AVC (Advanced Video Coding)

This letter deals with the basic principles and functions of the new compression standard MPEG-4 AVC, which has been developed for an effective compression of the digital video data; for digital signals of the high definition television (HDTV) especially.

- RICHARDSON, I. E. G. H.264 and MPEG-4 Video Compression. San Francisco: J. Willey and Sons, 2004.
- LISKA, D. Furter development of the project DVB (Dalsi vyvoj projektu DVB). In Proceedings of the conference Radiokomunikace 2005. Pardubice, 2005. (in Czech.)
- HURBAIN, I. The MPEG 4/AVC. Centre de reserche en informatique. EdM Paris, 2004.
- H.264/MPEG-4 AVC from Wikipedia. http://en.wikipedia.org/wiki/H.264.

Keywords: Video compression, encoder, algorithm, television technology, profile, level, sampling format