Applications for MDA array antennas have ranged from L and S-Band mobile communications systems to large aperture L, C, and X-Band synthetic aperture radar antennas and to higher frequency Ku and Ka-Band arrays for multimedia communications. Extensive R&D has supported the development of innovative high-performance technologies, which often redefine the state-of-the-art in the industry. Requirements have been for single and dual linear polarization, single and dual circular polarization, single and dual frequency bands, single and multiple beam applications, fixed and steerable beam designs, passive arrays and active phased arrays, receive systems, transmit systems, and transmit/receive systems, and very high-power PIM free arrays.