2001/4

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Results of Indoor Propagation Measurement Campaign at 1900 MHz
(Společnost pro radioelektronické inženýrství, 2001-12) Pechač, Pavel; Klepal, M.; Zvanovec, S.
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.
The Laboratory of Wireless and Mobile Communications
(Společnost pro radioelektronické inženýrství, 2001-12) Hanus, S.
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.
Ground Radar Target Classification Using Singular Value Decomposition and Multilayer Perceptron
(Společnost pro radioelektronické inženýrství, 2001-12) Matousek, Z.; Kurty, J.; Mokris, I.
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.
Dipole Array Excited by Slots in its Coaxial Feeder
(Společnost pro radioelektronické inženýrství, 2001-12) Cernohorsky, D.; Novacek, Z.
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.
Neural Networks in Antennas and Microwaves: A Practical Approach
(Společnost pro radioelektronické inženýrství, 2001-12) Raida, Zbyněk
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.

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