Impedance effects on electromagnetic susceptibility
Abstract
This report studies the impedance effects on electromagnetic susceptibility for various loading conditions. From measurements of the selfimpedance (Z sub A) and received voltage across 50 ohms at the terminals of a generic test object, a Thevenin equivalent circuit model is derived. Then, using this model, the load voltage, current, spectral energy density and accumulated energy are computed for several interesting load impedances. Of interest are two worst cases where the load impedance is the complex conjugate of Z sub A and the conjugate pure reactance of Z sub A. Another case of particular interest is where the load impedance is that of an electronic unit representing that of a typical subsystem designed for operation at much lower frequencies. These three cases are compared with the voltage, current and energy at a 50 ohm load. It is concluded that the load voltage, current, spectral energy density and accumulated energy of the two conjugate cases can be one or two orders of magnitude larger than that for the 50 ohm case as might be expected. However, load voltage, current, and spectral energy density at the input of the electronic units tested are comparable to that of the 50 ohm case. The spectral energy density responses are generally within a factor of two (+/ 3 dB), but may be as large as a factor of three (+/ 5 dB) over narrow frequency bands.
 Publication:

NASA STI/Recon Technical Report N
 Pub Date:
 June 1987
 Bibcode:
 1987STIN...8729719N
 Keywords:

 Electrical Impedance;
 Equivalent Circuits;
 Magnetic Permeability;
 Spectral Energy Distribution;
 Electromagnets;
 Energy Spectra;
 Flux Density;
 Mathematical Models;
 Microwave Equipment;
 Communications and Radar