Design characteristics of the AMSAR airborne phased array antenna

This paper describes the key development tasks of an airborne active phased antenna carried out in the European AMSAR programme. The design of this antenna is based on a circular array with 1000 radiating elements operating in the X-band, each being linked to a dedicated transmit/receive module (T/R module). Because the chosen T/R modules are capable of controlling phase as well as amplitude transmission in each array channel, a very flexible steering of the radiation characteristics is possible. The antenna beam can be electronically steered over a wide scan region (±60°) and additionally the shape of the beam can be easily matched to various radar missions. In the AMSAR active phased array antenna, the array configuration provides signal access to several sub-arrays. This is the basis for the application of adaptive beamforming methods (ABF) in receive operation for the suppression of jammer signals