Design and testing of a large airborne phased array

Two large airborne phased-array antennas were designed and built for two E-9A aircraft in support of missile testing over the Gulf of Mexico. The antenna is a one-dimensional scan, multiple-channel phased array with a length of 30 ft and a height of 30 in that operates at 2.2 to 2.4 GHz. The design approach and performance testing are described. An important measure of antenna performance is its gain-to-temperature ratio (G/T). Based on the mission requirements, the antenna had to achieve a minimum G/T of 5.1 dB over the entire scan volume (+or-60 in azimuth and altitudes from sea level to 25000 ft). Much of the antenna design and testing activities focused on meeting this G/T requirement in an airborne environment. The calculated and measured G/T values with the main beam electrically steered to broadside are compared. The G/T is about 5 dB lower at +or-60 degrees than at broadside.<>