Coherent receiver design and aperture expansion beamforming for frequency diverse array radar

Frequency diverse array (FDA) radar has attracted considerable attention in interference suppression due to its range-angle dependent beampattern property. However, the full-band coherent receiver design is sophisticated and expensive. Furthermore, prior research on FDA radar adaptive beamforming failed to suppress adjacent-target interference because of insufficient beam resolution. This paper aims to develop a receiver architecture based on fractional domain signal separation and to investigate aperture expansion adaptive beamforming based on interference-noise covariance matrix reconstruction and signal of interest steering vector estimation. The proposed receiver design not only simplifies the structure and saves resources, but it can also effectively separate the received signals, particularly for the FDA radar's overlapping linear frequency modulated baseband emission waveforms. The proposed aperture expansion beamforming approach improves beam resolution of beamforming and effectiveness in adjacent-target interference suppression.