The multimode array-improved versatility through enhanced SAR

Today´s military aircraft must carry out various missions, some of them simultaneously. Consequently, antennas must be designed with the capability to function in a multiplicity of simultaneous as well as switchable modes. Slotted flat-plate arrays, with their unique ability to divide available aperture space among several antenna requirements, have become increasingly popular. Several recent design innovations have advanced the state of the art in attainable operational modes. Taking advantage of these approaches, one multimode antenna can now perform air-to-air pulse-Doppler monopulse, ground mapping, terrain following, and ground target tracking. Two multimode antennas are presented, one a simple and therefore less expensive design, the other a more complex configuration, a flat-plate array containing five separate apertures and eight RF outputs. Measured performance data, including far-field patterns when operating in the various modes, are shown