Beam broadening for active aperture antennas

A beam broadening technique for active aperture antennas for communication satellite downlinks is described. The elements of the active aperture are separated into two subarrays which are phased in two different directions so that the subarray beamwidths overlap. Each subarray is composed of every other element of the original active aperture so that the subarrays are interleaved. In this way, the phase centers of the subarray are close together, minimizing grating lobes caused by the phase center displacement of the two subarrays. Because the element spacing of the individual subarrays is twice that of the active aperture, further problems with grating lobes can be anticipated. However, the broader beamwidth requires less beam scanning to reach the edge of coverage, offsetting grating lobe difficulties. Example active aperture patterns are presented.<>