Mainbeam Notcher.

This report documents the development, evaluation, and design of mainbeam anti-jam techniques for successful operation of a C-band tracking radar in advanced ECM environments. The techniques addressed in this study employ an antenna array consisting of omnidirectional or high-gain subarray elements followed by a signal processor to remove mainbeam jamming and provide target detection and tracking. The signal processing techniques that were considered are similar well-known techniques used in the areas of adaptive array processing and high resolution spectrum estimation. Two procedures were developed and were shown to provide target detection in the presence of a high intensity mainbeam jammer. The extrapolation procedure employed extrapolation techniques to extend the apparent aperture of the antenna array and thereby achieve a narrow notch on the jammer while providing gain in the book direction of a nearby target. The maximum likelihood (ML) procedure provided both target detection and an estimate of its angle of arrival. The angle estimation feature offers a potential solution to the target tracking problem under mainbeam jamming conditions.