GENETIC ALGORITHM-CONFIGURED PLANEWAVE GENERATOR

The need exists to generate high-quality electromagnetic planewave enviroments over large assets or extended volumes for testing avionics suites installed on full-size aircraft. Previously, these conditions were realized only be using farfield ranges or large compact range configurations. We propose to investigate a unique solution to the problem. Instead of trying to generate a planewave enviroment over the entire volume, we propose to design a system that creates an incident field that is planewave in nature only over local points on the SUT. The test engineer indentifies the locations on an asset where the apertures of interest are located, and the planewave generator produces a field distribution where the incident field only over these locations have planewave amplitude, phase, and polarization relationships- -the field is free to assume any value in other areas of the test volume and on the asset where no specific value is demanded (say at a midpoint between two apertures). By relaxing the requirement on the EM field in the entire test volume, we have greatly reduced the overall complexity and defined a tractable problem that has a potential engineering solution. The system will be comprised of a set (three or four) of transmitting stations, each an array of broadband elements with individual excitation vector (amplitude and phase) control. The exact aperture locations on the asset and the direction and polarization of the desired planewave are input to a genetic algorithm. The genetic algorithm researches within the near infinite family of excitation vectors for one that produces a radiated field that meets the prescribed criteria, i.e. produces a field distribution with asset's apertures. This excitation then drives the array elements to create the desired EM enviroment.