SMART GROUND-TERMINAL ANTENNA FOR GEOSTATIONARY SATELLITES IN SLIGHTLY INCLINED ORBITS

A system for communication comprises an antenna system that includes a reflector having a focus and a feed array positioned at or near the focus and having N feed elements, N being an integer greater than 1. The N feed elements receive N feed signals that result from illumination of the N feed elements by a target signal incident on the reflector from a slow-moving signal source. A first N-to-N Fourier Transform device performs a spatial Fourier Transform on the N feed signals to generate N wavefront signals which are orthogonal to one another. Band-pass filters filter the N wavefront signals and output N filtered wavefront signals. Frequency down-converters down-convert the N filtered wavefront signals to an intermediate frequency or baseband frequency and generate N frequency-down-converted wavefront signals. Analog-to-digital converters digitize the N frequency-down-converted wavefront signals and output N digital wavefront signals. A correlation processor computes a phase slope across the N digital wavefront signals. A direction-of-arrival processor determines a direction of arrival of the target signal based on the phase slope.