# April 2003, Volume 12, Number 1

**V. Navratil, M. Leone**
[references] [full-text]

The Effect of Differential Driver Asymmetries on Common-Mode Frequency
Spectrum

A frequency spectra determination of the common-mode signal due to the differential driver asymmetries is presented. The analytical expression for the Fourier series is developed and the evaluations for different dependencies are introduced. The effect of the skew time and amplitude imbalance is shown in a parameter study. From the general analytical solution a compact expression for small amplitude imbalances is deduced. This allows to study the influence of the driver time skew on the resulting common-mode signal, which is the source of unwanted electromagnetic radiation. It is found that for realistic driver parameters, the driver skew is the most responsible.

- LEONE, M., NAVRATIL V. Analysis of the common mode radiation from differential signalling on printed circuit boards. In Proc. of the Conference EMC Zurich 2003. Zurich, 2003 (accepted).
- ILAVARSAN P. Simulation/experimental analysis of single/differential signals crossing splits. In Proc. of the 2001 IEEE International Symposium on Electromagnetic Compatibility. Montreal, 2001.
- LEONE, M. Design expressions for the trace-to-edge common-mode inductance of a printed circuit board. IEEE Trans. on Electromagnetic Compatibility, 2001, vol. 43, no. 4.
- CIZEK, V. Discrete Fourier transforms and their applications. Bristol: Adam Hilberg Ltd., 1986.
- BRIGHAM, E. O. The fast Fourier transform. New Jersey: Prentice Hall, 1986.
- PAPOULIS, A. The Fourier integral and its applications. London: Mc Graw-Hill, 1962.
- HOEFT, O.L., KNIGHTEN, J.L. Spectral analysis of common mode currents on fibre channel cable shields due to skew imbalance of differential signals operating at 1.0625 Gb/s. In Proc. of the 1998 IEEE International Symposium on Electromagnetic Compatibility. Seattle, 1998.
- KNIGHTEN, J. L. Common-mode current harmonics on differential pair cable shields operating in a regime as high as 2.125 Gb/s. In Proc. of the 2001 IEEE International Symposium on Electromagnetic Compatibility. Montreal, 2001.

**M. Grabner, V. Kvicera**
[references] [full-text]

Refractive Index Measurement at TV Tower Prague

Propagation related parameters are used for design and frequency planning of microwave networks. Atmospheric refractive index is the important parameter that influences the propagation of electromagnetic waves during so-called "clear sky" conditions. The refractive index measurement, which was launched in TESTCOM, is presented in this paper. Some statistical characteristics and their utilization are introduced.

- MAZANEK, M., PECHAC, P., VOKURKA, J. Anteny a sireni vln (Antennas and propagation of waves). Praha: CVUT Publishing, 1998.
- Rec. ITU-R P.530-9 Propagation data and prediction methods required for the design of terrestrial line-of-site systems. Geneva, 2001.

**O. Fiser**
[references] [full-text]

Site Diversity Gain Estimated from Rain Rate Records

The site diversity is used to mitigate the rain attenuation on satellite links. The attenuation is estimated through the rain rate-rain attenuation conversion based on the Assis-Einloft physical model in this study. Through the comparison of instantaneous attenuations at two receiving sites the site diversity gain is estimated. Examples of rain rate measurements in the Czech Republic followed by the site diversity gain estimation are added. This gain is greater on west-east situation of receiving sites achieving 10 dB on 0.01% exceedance level/100 km.

- ASSIS, M. S., EINLOFT, C. M.: A simple method for estimating rain attenuation distribution. In Proceedings of the Conference URSI. La Baule, 1977, p. 301
- HAJNY, M., MAZANEK, M., FISER, O. Bi-static scattering function - radiation pattern calculation. In COST Project 255, MC5 Meeting (CP51A09). Vigo, 1998, p. 1-17
- FISER, O. On the tipping-bucket rain measurement applied to microwave propagation (theory and actual results). In Proceedings of URSI F Open Symposium. Garmisch Partenkirchen, 2002 (CD).

**V. Schejbal, J. Novak, S. Gregora**
[references] [full-text]

Comparison of CAD for Rectangular Microstrip Antennas

Calculations of several cases for rectangular microstrip antennas using more accurate cavity model have been compared with the conventional cavity calculations, expressions generated by curve fitting to full wave solutions and published experimental values for a variety of different substrate thickness and patch sizes with width to length ratio of 1.5 and with r = 10.8 and r = 2.33.

- CARVER, K. R., MINK, J. W. Microstrip antenna technology. IEEETransaction on Antennas and Propagation, 1981, vol. 29, no. 1, p. 2to 24.
- COLLIN, R. E. Antennas and radiowave propagation. New York:McGraw-Hill, 1985, p. 273 - 283.
- LEE, K. F., CHEN, W. Advances in microsptrip and printed antennas.New York: J. Wiley and Sons, 1997.
- SCHEJBAL, V. CAD of rectangular mircostrip antennas. Radioengineering,1999, vol. 8, no. 3, p. 17 - 20.
- POZAR, D. M. Antenna design using personal computers. Dedham:Artech House, 1985.
- SAINATI, R. A. CAD of microstrip antennas for wireless applications.Dedham: Artech House, 1996.
- CHANG, E., LONG, S. A., RICHARDS, W. F. An experimentalinvestigation of electrically thick rectangular microstrip antennas.IEEE Transaction on Antennas and Propagation, 1986, vol. 34,no. 6, p. 767 - 772.

**V. Schejbal, Z. Raida, Z. Novacek**
[references] [full-text]

Comparison of CAD Formulas, Method of Moments and Experiments for
Rectangular Microstrip Antennas

Calculations of several cases for rectangular microstrip patch antennas using more accurate cavity model have been compared with the conventional cavity calculations, expressions generated by curve fitting to full wave solutions and method of moments. Calculated as well as experimental values have been studied for different thickness, patch sizes and substrate materials with different permittivities and losses.

- CARVER, K. R., MINK, J. W. Microstrip antenna technology. IEEETrans. on Antennas and Propagation, 1981, vol. 29, no. 1, p. 2 - 24.
- COLLIN, R. E. Antennas and radiowave propagation. New York:McGraw-Hill, 1985, p. 273 - 283.
- LEE, K. F., CHEN, W. Advances in microstrip and printed antennas.New York: John Wiley & Sons, 1997.
- SCHEJBAL, V. CAD of rectangular microstrip antennas. Radioengineering.1999, vol. 8, no. 3, p. 17 - 20.
- POZAR, D. M. Antenna design using personal computers. Dedham:Artech House, 1985.
- SAINATI, R. A. CAD of microstrip antennas for wireless applications.Dedham: Artech House, 1996.
- SCHEJBAL, V. Investigation of CAD for rectangular microstrip antennas.In Proceedings of the 10th Conference on Microwave TechniquesCOMITE. Pardubice (Czech Republic), 1999, p. 135 - 138.
- SCHEJBAL, V., RAIDA, Z., NOVACEK, Z. CAD formulas andexperiments for rectangular microstrip antennas. In Proceedings ofthe 13th Conference on Microwaves MIKON. Wroclaw (Poland),2000, Vol. 1, p. 159 - 162.
- SCHEJBAL, V., NOVAK, J., GREGORA, S. Comparison of CADfor Rectangular Microstrip Antennas. Radioengineering, 2003, vol.12, no. 1, p. 12 - 15.
- CERNOHORSKY, D., RAIDA, Z., SKVOR, Z., NOVACEK, Z.Analysis and optimization of microwave structures (in Czech). Brno:VUTIUM Publishing, 1999.

**P. Hajach, R. Hartansky**
[references] [full-text]

Resistively Loaded Dipole Characteristics

Resistively loaded dipole is very often used to measuring the electromagnetic field in EMC testing. The dipole is a traveling wave antenna, where its resonance is eliminated. The paper includes the computation of the current distribution and radiation pattern of this dipole. The characteristics were obtained by moment method, Hallen method and Wu-King method. The unique modification of presented methods has been made. The comparison of used methods has been presented in paper conclusions.

- WU, T. T., KING, R. W. P. The cylindrical antenna with nonreflecting resistive loading. IEEE Transactions on Antennas and Propagation. 1965, vol. 13, no. 3, p. 369-373.
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- HARTANSKY, R., KOVAC, K., HALLON, J. Effective modification of moment method for antenna simulation. In Proceedings of 9th Conference on Microwave Techniques. Pardubice (Czechia), 1997, p. .262-265
- MAGA, D., WAGNER, J. Numericke riesenie elektromagnetickych poli v elektrickych strojoch (Numerical solution of electromagnetic fields in electrical engines). Odborny casopis pre elektrotechniku a energetiku (Special journal on electrical engineering and power engineering). 1999, roc. 5, special issue ELOSYS 99, pp. 77 - 79
- KING, R. W. P. Theory of linear antennas. Cambridge MA: Harvard Univ. Press, 1956.
- MILJAVEC, D., JEREB, P. Synchronous reluctance motor and in-duction motor using the same stator frame. In Proceeding of ICEM 96. Vigo (Spain), 1999

**T. Fryza, S. Hanus**
[references] [full-text]

Algorithms for Fast Computing of the 3D-DCT Transform

The algorithm for video compression based on the Three-Dimensional Discrete Cosine Transform (3D-DCT) is presented. The original algorithm of the 3D-DCT has high time complexity. We propose several enhancements to the original algorithm and make the calculation of the DCT algorithm feasible for future real-time video compression.

- WESTWATER, R., FURHT, B. Real-Time Video Compression. Techniques and Algorithms. Boston: Kluwer Academic Publishers, 1997. ISBN 0-7923-9787-8.
- CHROMY, I. Compression of Digital Video Signals. Postgraduate thesis. Brno: Department of Radio Electronics FEI VUT, 1999.
- RILEY, M.J., RICHARDSON, I.E.G. Digital Video Communica-tions. Boston - London: Artech House, 1997. ISBN 0-89006-890-9.
- FRYZA, T. Three-Dimensional Discrete Cosine Transform 3D-DCT and methods of calculation. In Proceedings of 8th conference Student EEICT 2002, vol. I., p. 57-59.
- FRYZA, T. Compression of Video Signals by 3D-DCT Transform. Diploma Thesis. Brno: Department of Radio Electronics FEKT VUT, 2002.
- BURG, A., KELLER, R. A Real-Time Video Compression System. In Proceedings of MoMuC2000, Tokyo, 2000.

**J. Pospisil, Z. Kolka, S. Hanus, V. Michalek, J. Brzobohaty**
[references] [full-text]

Optimized State Model of Piecewise-Linear Dynamical Systems

The conditions for an optimized design of the second dynamical system having low eigenvalue sensitivities are directly derived. Their more general form is in accordance with the previous results obtained by using linear topological conjugacy.

- WU, C.W., CHUA, L.O. On Linear Topological Conjugacy of Lur'e Systems. IEEE Trans. Circ. Syst. - I: Fundamentals..., 1996, 43(2), p. 158-161.
- KOLKA, Z. Synthesis of Optimized Piecewise-Linear System Using Similarity Transformation-Part I: Basic Principles. Radioengi-neering, 2001, vol. 10, no.3, p.5-7.
- POSPISIL, J., KOLKA, Z., HORSKA, J. Synthesis of Optimized Piecewise-Linear System Using Similarity Transformation - Part II: Second-Order Systems. Radioengineering, 01, vol. 10, no. 3, p. 8-10.
- POSPISIL, J., KOLKA, Z., HANUS, S., BRZOBOHATY, J. Synthesis of Optimized Piecewise-Linear System Using Similarity Transformation - Part III: Higher-Order Systems. Radioengineering, 2002, vol. 11, no. 1, p. 4-6.

**J. Pospisil, Z. Kolka, S. Hanus, T. Dostal, J. Brzobohaty**
[references] [full-text]

New Second-Order Optimized Filter Design

Starting from the piecewise-linear (PWL) autonomous dynamical system optimized from the eigenvalue sensitivities viewpoint the corresponding optimized non-autonomous linear (single-input single-output) system is derived. Such a design procedure gives the possibility to obtain minimum eigenvalue sensitivities with respect to the change of the individual model parameters also for non-autonomous linear systems. Two examples of the system having the complex conjugate poles and zeros, i.e. the optimized second-order band-reject and all-pass filter design, are shown.

- POSPISIL, J., BRZOBOHATY, J., HORSKA, J.Mutual relation between multiple-input linear and multiple-feedback piecewise-linear dynamical systems. Radioengineering, 2000, vol. 9, no.4, pp. 28-32.
- POSPISIL, J., KOLKA, Z., HORSKA, J. Synthesis of optimized piecewise-linear system using similarity transformation - part II: second-order systems. Radioengineering, 2001, vol. 10, no.3, pp. 8-10.
- POSPISIL, J., BRZOBOHATY, J. Elementary canonical state models of Chua's circuit family. IEEE Trans. Circ. Syst.-I:
- POSPISIL, J., BRZOBOHATY, J., KOLKA. Z.,. HORSKA, J. Simplest ODE equivalents of Chua's equations. Intern. Journ. of Bifurcation & Chaos, 2000, 10(1), pp. 1-23 (Tutorial & Review paper).
- WU, C. W., CHUA, L. O. On linear topological conjugacy of Lur'e systems. IEEE Trans. Circ. Syst. - I: Fundamentals..., 1996, 43(2), pp. 158-161.
- KOLKA, Z. Using similarity transformation for nonlinear system synthesis. In Proc. Radioelektronika' 2001, Brno, 2001, pp. 5-7.
- POSPISIL, J., BRZOBOHATY, J., KOLKA ,Z.,. HORSKA, J., DOSTAL, T. Dynamical systems with low eigenvalue sensitivities. In Proc. MIC'2001, Innsbruck, 2001, pp. 217-219.
- M. S. SCHAUMAN, M. S. et al. Design of Analog Filters. Passive, Active RC, and Switched Capacitor. Engelwood Cliffs, NJ: Prentice-Hall, 1990.
- HANUS, S. Realization of third-order chaotic systems using their elementary canonical state models. In Proc. Radioelektronika'97, Bratislava, 1997, pp. 44-45.
- POSPISIL, J., BRZOBOHATY, J., KOLKA, Z., HANUS, S., MICHALEK, V. Optimized state model of piecewise-linear dynamical systems. Radioengineering, 2003, vol. 12, no.1, pp. 27-29.

**P. Kovar**
[references] [full-text]

Generation of the Narrow Band Digital Modulated Signals Using
Quadrature Digital Upconverter

The paper deals with the modern approach to generation of digital modulated signals at intermediate frequency in digital way. The common digital modulator is based on analogue Quadrature modulator. The modern VLSI integrated circuits enable to implement this signal processing method in digital form. Analog and digital approaches are compared in this document. The measurement of narrow band D8PSK modulation signal generated by Quadrature Digital Upconverter is presented in this paper.

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**K. Vlcek**
[references] [full-text]

Advanced Error-Control Coding Methods Enhance Reliability of
Transmission and Storage Data Systems

Iterative coding systems are currently being proposed and accepted for many future systems as next generation wireless transmission and storage systems. The text gives an overview of the state of the art in iterative decoded FEC (Forward Error-Correction) error-control systems. Such systems can typically achieve capacity to within a fraction of a dB at unprecedented low complexities. Using a single code requires very long code words, and consequently very complex coding system. One way around the problem of achieving very low error probabilities is turbo coding (TC) application. A general model of concatenated coding system is shown - an algorithm of turbo codes is given in this paper.

- AITSAB, O., PYNDIAH, R. Performance of Reed-Solomon BlockTurbo Code. In IEEE Global Telecomm. Conf. London, UK, Nov.18-22, 1996, pp. 121-125.
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