Predicting detailed electromagnetic interference rejection requirements using a knowledge-based simulation approach

This paper overviews the application of a knowledge-based modeling and simulation approach for generating and analyzing a valid computational electromagnetics (CEM) structure model in order to determine detailed interference rejection requirements. An expert system is first used to generate the computational model of a complex structure comprised of co-located RF transceivers. Electromagnetic interference (EMI) analyses are performed on the model in both the frequency and time domains. This involves the use of the short-term Fourier transform (SFT) where the time scale is initially subdivided into contiguous segments in an effort to study time-dependent interactions among receptors and interferers, deduce the probability of spectral overlap, and estimate the degree of interference. Coupling is computed in the frequency domain using exact GTD theory where losses are calculated for high probability EMI cases. Frequency-domain results are ranked to determine the severity of EMI and to specify initial corrective measures with the aid of the expert system. The knowledge-base is then used to "monitor" the signal environment in the time domain and select the detailed interference rejection scheme(s) appropriate for mitigating the effects of interferers present at a victim receptor.