Simulation of Amplitude/Phase Nonlinearities of a Satellite Communication Terminal using Quasi-Statistical Network Modeling

When transmission elements or components are cascaded and inter-connected with cables or waveguides, with mismatches at the junctions, it is possible to predict the transmission (amplitude and phase) response from a network model. The response T(j¿) is composed of a deterministic component in the form of the gain functions Gk(j¿) and the random ripple caused by reflections (parameter Di(j¿)) at the discontinuities. The reflections, expressed by recurring polynomial functions, have been generalized to include reciprocity at the discontinuities. Corrective factors Ca and Cb have been included in the model to correct for errors in VSWR measurements of cables and waveguides. The principles were illustrated by an example for the case of a waveguide network where the objective was to implement an isolator to effectively reduce mismatch nonlinearties. Finally, transmission nonlinearity performance of a medium satellite earth terminal consisting of 20 cascaded components was analyzed and it was shown with actual test data that the results of analysis were comparable.