Quantitative analysis of intermodulation product interference

An analytical technique for estimating the absolute signal strength of externally generated intermodulation (IM) product interference is given. The modeling approach detailed is intended to augment previously published work by providing greater insight into the mechanisms generating IM product interference and may find direct application for siting situations in which equipment parameters and layout are well defined. The layout for a simplified model used to determine externally generated IM product levels is shown; a transmitting antenna illuminates a dipole antenna terminated in a nonlinearity, which reradiates IM product interference that is coupled into the receiving antenna. Actual signal levels are calculated for a canonic case involving a parasitic, center-fed dipole terminated in a nonlinear diode-type junction. The results can be applied readily to any nonlinear function and radiating system