Passive Inter-moduiation Analysis Of Scatterer

Passive inter-modulation (PIM) is caused by the inherent nonlinearities of thepassive devices and components. Nonlinearities include contact nonlinearity andmaterial nonlinearity. PIM caused by the contact nonlinearity and material nonlinearityare discussed in this article. The prime tasks and outcomes are as follows:1. Researches are done to study the contact and material nonlinearity based on thegeneration mechanism of passive inter-modulation, and formulations are derived topredict the frequencies and orders of PIM.2. The contact nonlinearity model is proposed based on the transmission line theory.The scattered field integral equations of the one-dimensional and two-dimensionalcontact nonlinearity are derived by adding the corrective nonlinear surface current terminto the standard time-domain physical optics linear surface current. Then PIM level canbe obtained by taking fast Fourier transform of the solved scattered field. Finally,simulation examples are given to summarize the influence rules of the relative factorson PIM.3. The material nonlinearity EM model is introduced and a modified FDTDcalculation method with much less computation time is proposed here. Its feasibility andvalidity are proved by simulation examples.