Aspects of adaptive beamforming with an AESA radar with subarray architecture

The invocation of the numerous operational advantages feasible with an active electronically steered array (AESA) radar relies heavily on the capability to apply adaptive beamforming (ABF) and space-time adaptive processing (STAP) procedures to adapt to changing interference and clutter environments and conditions. ABF provides an electronic counter-counter measure (ECCM) capability. It uses the degrees of freedom (DOF) available with a spatial multichannel system to suppress jamming sources. STAP enhances the detection in the presence of clutter. It generalises ABF in that it also uses temporal DOFs. The radiating elements of an AESA radar are distributed on a planar surface such that the spatial sampling condition is obeyed. The latter implies that the distance between adjacent radiating elements has to be in the vicinity of half the RF wavelength. The paper presents an outline of the relevant system level issues specific to the development of ABF AESA based airborne applications and approaches to solutions. Also selected results of performance assessments are discussed along with some open questions.