A W-Band Choke-Ring Encircled Focal Plane Array of Full-Metal Elements for Reflector Antennas with over 50%-Efficiency High Cross-Over Beams

Journal article, 2024

This work presents a novel W-band (92-96 GHz) focal plane array (FPA) for 50 dBi-reflector antennas intended for the next-generation point-to-point communication links with antenna mast sway compensation. The FPA comprises seven metal waveguide elements arranged in a hexagonal lattice, ensuring the cross-over level of the corresponding reflector beams above-6 dB. The primary challenge of this design is to realize efficient illumination of the reflector for the on-axis and off-axis beams, while keeping a minimum beamforming complexity (i.e., one element per beam) and overcoming array implementation challenges associated with high frequencies. This is accomplished by (i) a high decoupling level of the FPA elements (<-24 dB) and shaping their individual element patterns via a dedicated aperture pin structure between them; and (ii) encircling the FPA aperture with a periodically perforated choke ring pair to further improve the illumination by off-set elements. The FPA performance, evaluated on an offset parabolic reflector with F/D=0.35, exhibits 52-68% efficiency, close beam overlap, and good impedance matching. Measurements of the FPA prototype verify the results for all characteristics; the latter are competitive with state-of-the-art solutions.