Radiating elements for wideband electronically scanned arrays

The initial applications of active electronically scanned array antennas (AESA) in radar (and other) applications have been in areas where a narrow operating bandwidth (<10%) has been acceptable. However, although the cost of an AESA has reduced in recent years it is still a relatively expensive asset. Also, space on a military platform such as a fighter aircraft is at a premium. There is therefore a need to share AESA apertures between various functions. As a result, system requirements are emerging that demand much wider bandwidth AESAs (sometimes well in excess of 2:1). This presentation briefly describes the rationale for wider band AESA antennas. It then describes the constraints that a wideband phased array places on a radiating element that would not apply to a free space antenna. The development of wideband radiating elements is then reviewed with particular reference to two state-of-the-art papers that were recently published in the EMRS DTC held in July 2007.