Multi-beam phased arrays using dual apertures

The problem of transmitting multiple radar beams with an active-aperture phased arrays is considered. Several approaches are considered and the approach selected is to use a dual aperture which consist, of an active-aperture transmit array and a large receive array. It is shown that the optimal operating point is where the costs of the small, but expensive, transmit array is equal to the large, but simpler, receive array. Presently under consideration for the receive array are (1) phase shifters, (2) space feed lenses, and (3) a fiber optic feed