Modified Binomial Power Distribution Beamformer for Switched-Beam Circular Array

In this paper, we proposed a modified binomial power distribution circular beamforming network (BFN) with a single input port at the center and 12 antenna ports uniformly located along the outer rim of the BFN for full 360° azimuth coverage switched-beam circular antenna array. By combining and interleaving three modified binomial power distribution circuits (PDCs) with three two-way power combining circuits, a compact full horizontal plane coverage beam-switching beamformer is formed. While six switches are needed in the proposed BFN, a simplified prototype BFN without the switches is fabricated and tested for preliminary verification. Measured results agree well with those simulated. The proposed 1×12 modified binomial power distribution circular beamformer possesses several advantages over conventional circular BFN designs, including compact size, single-layered structure, and a wide bandwidth up to 11.4% centered at 5.6 GHz.