Low-angle tracking using multifrequency sampled aperture radar

A discussion is presented of the improvements that can be achieved in low-angle radar by using a sampled aperture radar (SAMPAR) and a new maximum likelihood (ML) algorithm. The SAMPAR system that is described herein is unique in that it has a wide-ranging multifrequency capability. The ML technique is unique, as well, because its estimation is based on the use of a highly refined signal model. It is shown, by using both simulated data and real data, that this combination, i.e., a SAMPAR system and the modified ML algorithm, provides a multiple signal resolution that exceeds any reported in the open literature. The measured data that are used in this study were recorded using a 32-element sampled aperture antenna on an 'over-water' path.