EMC problem

Abstract: New high-voltage power lines are often built in close proximity to MF/AM broadcast antennas The "skywire" which joins the tops of the power-line towers creates closed loops for RF current on the power line and its image in ground, and these loops can be resonant in the MF band If the broadcast antenna operates on such a resonant frequency, it induces large currents on the skywires and power-line towers, and "reradiation" from these induced currents can considerably alter the broadcast antenna's radiation patterns This paper uses computer modeling to systematically examine several techniques for "detuning" the power line, namely: isolating towers from the skywire, series insulators in the skywires, stub detuners on the skywires, and short capacitively terminated stub detuners on the towers The mechanism which makes each detuner effective is seen from the RF current distribution computed for the power line and detuner The bandwidth of each detuner is assessed Consideration is given to the difficulties that can arise in the implementation of each detuner design on a real power line All of these detuner designs have been tested by scale-model or full-scale measurements Only when detuning has been made a systematic economical procedure can this special EMC problem be regarded as solved

Abstract: In this contribution we deal with the development of a novel hybrid Finite Difference-Integral Equation method (FDIE) in which the efficient Integral Equation method (I.E.) is combined with the very flexible Finite Difference method (FDTD) / the Transmission Line Matrix (TLM) method. With that the FDIE method has got the high flexibility of a space discretizing method and the efficiency of the Integral Equation method for the analysis of large homogeneous regions. So the FDIE method is applicable for the analysis of EMC problems. It makes possible the efficient computation of complex structures which are coupled by their far fields. In a typical EMC problem the method is applicated to the modeling of the radiation from apertures in metallic enclosures which is a. The numerical results of the FDIE method are compared with results obtained by the TLM method and with data from literature, showing a very good agreement.

Abstract: A new TLM model for thin finite conductivity films is described. The basis of the method is the representation of the boundary by an equivalent one-dimensional lossy transmission line which is integrated into a parallel three-dimensional TLM code called PSTRIPES. Two applications of the model are considered. The first is an EMC problem where the authors compute the response to a hybrid structure. The other is a microwave problem where we model a travelling-wave tube with graphite loading.

Abstract: The essential features of transmission-line modeling (TLM) and its relevance to EMC problems are briefly described. The manner in which an EMC problem can be modeled using TLM is outlined, and three important applications are presented. Results are shown for a spherical dipole antenna placed near conducting walls, where a detailed model of the antenna and the surrounding space is used to determine the radiation resistance and its variation with proximity to the walls. The electromagnetic emission pattern from a typical device under test placed in a practical environment is determined by simulation. The current induced on wires placed on either side of a thin conducting plate is obtained by TLM, and the results are compared with measurements. Although a relatively coarse mesh of points has been used, the comparisons are very encouraging. Further developments to the code, which will allow a more efficient treatment of fine features and enhance the poser of the method to solve realistic EMC problems, are discussed. >