A simulation-before-test method has been applied to the linear and nonlinear microwave built-in test (BIT) problem. Fault simulation via a harmonic balance simulator is used to analyze and optimize BIT hardware placement based on figures of merit such as fault coverage, ambiguity size, and part isolation. Fault models for a prototype microwave minisystem were developed along with models for the BIT hardware itself. The search method developed to automate the placement of BIT hardware is an essential design-for-test tool. The techniques developed were applied to an example system and results are given. 0 1994