An overview of methods for simulation of nonlinear IF radar hardware components at baseband frequencies

It is shown that the high sampling rate requirements of credible electronic countermeasure (ECM) simulations can be greatly reduced by developing baseband frequency models that are based on closed-form solutions, called nonlinear describing functions, which accurately define the effects that IF nonlinearities impose on realistic ECM signals. Two methods are given for obtaining the nonlinear describing function for any given nonlinearity: the transform method and the sinusoidal describing function method. An example of an ideal soft limiter shows that two methods yield identical nonlinear describing functions. However, the sinusoidal describing function method is much more readily applied than the transform method.