Frequency Offset Selection based adaptive 3D Beamforming in Planar Frequency Diverse Array

Frequency diverse arrays (FDAs) are gaining much popularity for their unique range angle dependent beampatterns. However, most of the researchers focus on linear frequency diverse arrays (LFDAs) and there is a shortage of existing research in other geometries of FDA, such as planar FDA (PFDAs). In this paper, 3D adaptive beamforming theory is explored in PFDA. Here, a unique frequency offset selection based 3D adaptive transmit beamforming is devised such that the target is illuminated adaptively by the maximum of the pattern and any unwanted source is suppressed by the null of the pattern. The proposed beamforming eliminates the use of phase shifters at the transmitter as well as at the receiver end, thereby promising reduced cost and receiver complexity. The paper further explores minimum variance distortionless response (MVDR) beamforming in PFDA and compares its performance with that of the proposed beamformer. Simulation results reveal that the proposed beamformer outsmarts other beamforming techniques in PFDA in terms of improved SINR, 3D steerability (range, elevation and azimuth), deeper nulls and sharp maxima.