December 2001, Volume 10, Number 4

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P. Pechac, M. Klepal, S. Zvanovec [references] [full-text]
Results of Indoor Propagation Measurement Campaign at 1900 MHz

For the design of indoor picocellular systems in the frequency band of 1800/2100 MHz, a signal propagation modelling is needed. Empirical and semi-empirical models represent an efficient approach to the coverage prediction. For these models, suitable empirical parameters must be provided. The indoor propagation measurement campaign in the frequency range of 1900 MHz was carried out in several multi-floored buildings in Prague and Brno . For the campaign a special portable measurement system was developed. Based on the measurement results, the model parameters were derived. Optimised parameters are presented for two basic models (empirical and semi-empirical) according to the indoor environment classification. The results are compared to standard models as well. Accuracy and validity of derived models are discussed.

  1. PECHAC, P., KLEPAL, M. Empirical Models for Indor Propa-gation in CTU Prague Buildings. Radioengineering, April 2000, vol. 9, no. 1, p. 31-36
  2. PECHAC, P., KLEPAL, M., MAZANEK, M. Indoor Propagation Modelling in Multi-Storey Buildings in Prague. In Proceedings of the Millennium Conference on Antennas & Propagation - AP2000, Davos, April 2000
  3. PARSONS, J. D. The Mobile Propagation Radio Channel, 2nd Edition. John Wiley and Sons, London, 2000
  4. Digital Mobile Radio towards Future Generation Systems. COST 231 Final Report, Brussels, 1996
  5. ITU-R Rec. P.1238 Propagation Data and Prediction Models for the Planning of Indoor Radiocommunication Systems and Radio Local Area Networks in the Frequency Range 900 MHz to 100 GHz. ITU, Geneva, 1997
  6. PECHAC, P., NISZNANSKY, M., HUDEC, P. System for 1900 MHz Mobile Measurements Controlled by PDA Computer. In Proceedings of the Workshop CAD & CAE 2000, Praha 2000, p. 16-18
  7. PECHAC, P., KLEPAL, M. Software pro navrh bezdratovych systemu uvnitr vicepodlaznich budov. In Proceedings of of the Workshop CAD&CAE 2000, Praha 2000, p. 1-4 (www.i-prop.cz)
  8. PECHAC, P., KLEPAL, M., NOVOTNY, K. Novel Approach to Indoor Propagation Modelling. Radioengineering, September 2000, vol. 9, no. 3, p. 12-16
  9. PECHAC, P., KLEPAL, M., MAZANEK, M. New Fast Approach to Wide-Band Propagation Prediction in Picocells. In Proceedings of the Conference ICAP 2001, Manchester, April 2001, p. 1.216-1.219

T. Farkas, P. Hajach [references] [full-text]
Analysis of Aperture-coupled Microstrip Antenna Using Method of Moments

A microstrip patch antenna that is coupled to a microstripline by an aperture in the intervening ground plane is analyzed by using the method of moments. Integral equation is formulated by considering the exact dyadic Green's function in spectral domain for grounded dielectric slab so that the analysis includes all coupling effects and the radiation and surface wave effects of both substrates. The combination of the reciprocity method analysis and a Galerkin moment method solution seems to be suitable for a number of planar antenna problems, especially when coupling slots in the ground plane are included. Results for antenna input impedance are compared with other authors and verified by experimental results.

  1. KAY FONG LEE, WEI CHEN Advances in microstrip and printed antennas. New York: John Wiley & Sons, 1997.
  2. POZAR, D. M. A reciprocity method of analysis for printed slot and slot-coupled microstrip antennas. IEEE Transactions on Antennas and Propagation. 1986, vol. 34, no. 12, p. 1439 - 1446.
  3. SULLIVAN, P. L., SCHAUBERT, D. H. Analysis of an aperture coupled microstrip antenna. IEEE Transactions on Antennas and Propagation. 1986, vol. 34, no. 8, p. 977 - 984.
  4. HARRINGTON, R. F. Field computation by moment methods, IEEE, New York, 1993.

D. Cernohorsky, Z. Novacek [references] [full-text]
Dipole Array Excited by Slots in its Coaxial Feeder

A technical analysis of the coaxial dipole-array excited by periodically distributed slots in common coaxial feeder is presented. The lossy transmission-line theory is applied for determination of the current on all parts of the system. Calculated results support some properties of the system, especially the radiation pattern and the input impedance.

  1. CERNOHORSKY, D., NOVACEK, Z. Radiation pattern and impedance of dipole excited by a slot in it coaxial feeder. In Proceedings of the International Conference Radioelektronika 2001. Brno: Brno University of Technology, 2001, vol. 1, p. 250 - 253.
  2. HAUSKA, M. Klasicky antifading ci ARPO? (A classical antifading or ARPO?). Telekomunikace. 1979, vol. 5, no. 6, p. 83-86.
  3. AJZENBERG, G. Z. Kurzwellenantennen (Short-wave antennas). Leipzig: Fachbuchverlag, 1954.

K. Hoffmann, J. Vajtr [references] [full-text]
Solenoid above Ground Plane - Equivalent Circuit

Wide-band vector measurements of transmission structures formed by solenoids with 2, 4 and 6 turns above ground plane were performed in the frequency band 45 MHz to 18 GHz. Novel equivalent circuits of these structures were designed. The equivalent circuits fit the measured data very well in the frequency band DC to 11 GHz. Comparison with models known up to now are given.

  1. WADELL, B. C. Transmission Line Design Handbook. Artech House, Boston, 1991.
  2. RHEA, R. W. A New Solenoid Model. In MIOP 2001 Conference Proceedings, Stuttgart (Germany), 8th - 10th May, 2001, p. 323 - 328, ISBN 3-924651-53-1.
  3. HOFFMANN, K., SKVOR, Z. HP 8410-PC Controlling System and PTP Vector Network Analyzer. In COMITE 97 Conference Proceedings, Pardubice, Czech Republic, October 1997, p. 159 - 162, ISBN 80-902417-0-0.
  4. http://www.czech-web.cz/~mide/prikl.htm

K. Hoffmann, V. Sokol, Z. Skvor [references] [full-text]
Arbitrary Q-factor Dielectric Resonator

New circuit component, active resonator, is proposed for use in microwave and millimetrewave circuits. It consists of a common resonator and an amplifier, compensating for losses in the resonator. Properly designed, such an arrangement behaves as a (passive) resonator with dramatically increased quality factor. High quality factors can be achieved even at millimetrewave frequencies, where common resonators suffer from losses due to small skin depths. Viability of the component is experimentally verified at microwave region using a TE01 dielectric resonator and an oscillator.

  1. VENDELIN, G. D., PAVIO, A. M., ROHDE, U. L. Microwave Circuits Designs Using Linear and Nonlinear Techniques. John Wiley & Sons, 1990.
  2. KHANNA, A., GARAULT, Y. Determination of Loaded, Unloaded, and External Quality Factors of a Dielectric Resonator Coupled to a Microstrip Line. IEEE Trans. Microwave Theory Tech. vol. MTT-31, no. 3, March 1983. p. 261-264.
  3. FIEDZIUSZKO, S. J. Microwave Dielectric Resonators. Microwave Journal. 1986, vol. 29, p. 189-200.
  4. HOFFMANN, K., SKVOR, Z. Active microwave and millimetrewave resonator. In EMC proceedings. London 2001, vol. 3, p. 17-20.

Z. Raida [references] [full-text]
Neural Networks in Antennas and Microwaves: A Practical Approach

Neural networks are electronic systems which can be trained to remember behavior of a modeled structure in given operational points, and which can be used to approximate behavior of the structure out of the training points. These approximation abilities of neural nets are demonstrated on modeling a frequency-selective surface, a microstrip transmission line and a microstrip dipole. Attention is turned to the accuracy and to the efficiency of neural models. The association of neural models and genetic algorithms, which can provide a global design tool, is discussed.

  1. HAYKIN, S. Neural Networks: A Comprehensive Foundation. Englewood Cliffs. Macmillan Publishing Company, 1994.
  2. CICHOCKI, A.,UNBEHAUEN, R. Neural Networks for Optimi-zation and Signal Processing. Chichester: J. Wiley & Sons, 1994.
  3. CHANG, P. R., YANG, W. H., CHAN, K. K. A Neural Network Approach to MVDR Beamforming Problem. IEEE Transactions on Antennas and Propagation.1992, vol. 40, no. 3, p. 313 - 322.
  4. MAILLOUX, R. J., SOUTHALL, H. L. The Analogy Between the Butler Matrix and the Neural-Network Direction-Finding Array. IEEE Antennas and Prop. Magaz. 1997, vol. 39, no. 6, p. 27 - 32.
  5. SAGIROGLU, S., GUNEY, K. Calculation of Resonant Frequency for an Equilateral Triangular Microstrip Antenna with the Use of Artificial Neural Networks. Microwave and Optical Technology Letters. 1997, vol. 14, no. 2, p. 89 - 93.
  6. MISHRA, R. K., PATNIAK, A. Neurospectral Computation for Complex Resonant Frequency of Microstrip Resonators. IEEE Microw. and Guided Wave Lett. 1999, vol. 9, no. 9, p. 351 - 353.
  7. BANDLER, J. W., ISMAIL, M. A., RAYAS-SANCHEZ, J. E., ZHANG, Q.-J. Neuromodeling of Microwave Circuits Exploiting Space-Mapping Technology. IEEE Trans. on Microwave The-ory and Techniques. 1999, vol. 47, no. 12, p. 2417 - 2427.
  8. WANG, S., WANG, F., DEVABHAKTUNI, V. K., ZHANG, Q.-J., A Hybrid Neural and Circuit-Based Model Structure for Microwave Modeling. In Proceedings of the 29th European Microwave Conference. Munich (Germany), 1999, p. 174 - 177.
  9. WU, S., VAI, M., PRASAD, S. Reverse Modeling of Microwave Devices Using a Neural Network Approach. In Proc. of the Asia Pacific Microwave Confer. New Delhi (India), 1996, p. 951 - 954.
  10. PATNIAK, A., PATRO, G. K., MISHRA, R. K., DASH, S. K. Ef-fective Dielectric Constant of Microstrip Line Using Neural Network. In Proceedings of the Asia Pacific Microwave Confe-rence. New Delhi (India), 1996, p. 955 - 957.
  11. GUPTA, K. C., WATSON, P. M. Applications of ANN Computing to Microwave Design. In Proceedings of the Asia Pacific Microwave Conference. New Delhi (India), 1996, p. 825 - 828.
  12. ANTONINI, G., ORLANDI, A. Gradient Evaluation for Neural-Networks-Based EM Optimization Procedures. IEEE Trans. on Microwave Theory and Tech. 2000, vol. 48, no. 5, p. 874 - 786.
  13. CHRISTODOULOU, C., GEORGIOPOULOS, M. Applications of Neural Networks in Electromagnetics. Norwood: Artech House, 2000.
  14. ZHANG Q. J., GUPTA, K. C. Neural Networks for RF and Mic-rowave Design. Norwood: Artech House, 2000.
  15. DEMUTH, H., BEALE, M. Neural Network Toolbox for Use with Matlab: User's Guide. Natick: The MathWorks Inc., 2000.
  16. HAUPT, R. L. An Introduction to Genetic Algorithms for Elec-tromagnetics. IEEE Antennas and Propagation Magazine. 1995, vol. 37, no. 2, p. 7 - 15.
  17. WEILE, D. S., MICHIELSSEN, E. Genetic Algorithm Optimiza-tion Applied to Electromagnetics: A Review. IEEE Trans. on Antennas and Propagation, AP-45, 3, March 1997, p. 343 - 353.
  18. JOHNSON, J. M., RAHMAT-SAMII, Y. Genetic Algorithms in Engineering Electromagnetics. IEEE Antennas and Propagation Magazine. 1997, vol. 39, no. 4, p. 7 - 21.
  19. ALTMAN, Z., MITTRA, R., BOAG, A. New Designs of Ultra Wide-Band Communication Antennas Using a Genetic Algorithm. IEEE Transactions on Antennas and Propagation. 1997, vol. 45, no. 10, p. 1494 - 1501.
  20. JONES, E. A., JOINES, W. T. Design of Yagi-Uda Antennas Using Genetic Algorithms. IEEE Transactions on Antennas and Propagation. 1997, vol. 45, no. 9, p. 1368 - 1392.
  21. YAN, K.-K., LU, Y. Sidelobe Reduction in Array-Pattern Synthesis Using Genetic Algorithm. IEEE Transactions on Antennas and Propagation. 1997, vol. 45, no. 7, p. 1117 to 1121.
  22. GEN, M. CHENG, R. Genetic Algorithms & Engineering De-sign. Chichester: John Wiley & Sons, 1997.
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  24. SCOTT, C. Spectral Domain Method in Electromagnetics. Norwood: Artech House, 1989.
  25. HERTZ, J., KROGH, A., PALMER, R. G. Introduction to the Theory of Neural Computation. Reading: Addison Wesley, 1991.
  26. HAYKIN, S. Adaptive Filter Theory, 2nd edition. Englewood Cliffs: Prentice-Hall, 1991.
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Z. Matousek, J. Kurty, I. Mokris [references] [full-text]
Ground Radar Target Classification Using Singular Value Decomposition and Multilayer Perceptron

The paper deals with classification of ground radar targets. A received radar signal backscattered from a ground radar target was digitized and in the form of radar signal matrix utilized for a feature extraction based on Singular Value Decomposition. Furthermore, singular values of a backscattered radar signal matrix, as a target feature, were utilized for Radar Target Classification by multilayer perceptron. In the learning phase of a multilayer perceptron we used the learning target set and in the testing phase the testing target set was used. The learning and testing target sets were created on the basis of real ground radar targets.

  1. BARATH, J., MOKRIS, I. Classification of Noised Images Using Different Models of Neural Networks. Bulletin of WAT, Warsaw, 1994, pp. 3 - 10.
  2. BOTHA, E. C., BARNARD, E., BARNARD, CH. J. Feature-based Classification of Aerospace Radar Targets Using Neural Networks. Neural Networks, 1996, vol. 9, no. 1, p. 129-142.
  3. GOLUB, G. H., REINSCH, C.,: Singular Value Decomposition and Least Squares Solutions. Numer. Math., 1970, 14, p. 403 to 420.
  4. DEPRETTERE, E.F. (Editor) SVD and Signal Processing: Algorithms, Applications and Architectures. Elsevier Science Publishers B.V. (North - Holland), The Netherlands, 1988.
  5. HANSEN, P.C. SVD - Theory and Applications. ISSN 0105-4988, Numerisk Institute, Lyngby, Denmark, 1984.
  6. INGGS, M. R., ROBINSON, A. D.,: Ship Target Classification Using Low Resolution Radar and Neural Networks. IEEE Trans. on Aerospace and Electronic Systems. 1999, vol. 35, no. 2, p. 386 - 392.
  7. MOKRIS, I. Theory and Application of SVD in Image Proces-sing. Military Academy Press, Liptovsky Mikulas, 1995, (in Slovak).
  8. MOKRIS, I. Application of Approximated Orthogonal Transfor-mations for Image Processing. Liptovsky Mikulas, 1995.
  9. MOKRIS, I., BARATH, J., SEMANCIK, L. Image Classification by Means of Singular Value Decomposition and Multilayer Perceptron. Neural Network World, 1995, No. 2, pp. 191-198.
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S. Hanus [references] [full-text]
The Laboratory of Wireless and Mobile Communications

The paper presents the basic information about establishing of the laboratory for Mobile Communications on the Dept. of Radio Electronics, Brno University of Technology. This information allows to experts from the practice to obtain the general notion about the extent of theoretical knowledge and practical experiences of our students in this field. This information can be also useful for the specialists from universities comparing simple their pedagogical activity in this field respecting the activity in another institute.

  1. HANUS, S. The Education of Wireless and Mobile Communications Problems on Institute of Radio Electronics, Brno University of Technology. In Proceedings of Czech-Slovak Conference MOBILE COMMUNICATIONS. Bratislava 2000
  2. HANUS, S. The Laboratory of Wireless and Mobile Communications on Institute of Radio Electronics, FEECS, Brno University of Technology. In Proceedings of the 11th International Czech-Slovak Scientific Conference RADIOELEKTRONIKA 2001. Brno 2001, p. 306-309. ISBN: 80-214-1861-3
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