A Coherent Multiple Beamforming Network for a Non-uniform Circular Antenna Array

This work proposes and describes a modular and innovative beamforming network (BFN) to feed a nonequally spaced circular antenna array. The structure is based on a set of alternated power combiners and dividers that delivers a Gaussian-like amplitude distribution and coherent (in-phase) signals. A multiple beam antenna system to generate two main beams in the same aperture with a coherent network for a nonuniform array with beam shaping and beam steering properties is simulated and analyzed. Furthermore, a comparative analysis based on uniform and nonuniform circular antenna arrays fed by the proposed coherent network is conducted. The complex signals and the nonuniform circular aperture are optimized using the well known differential evolution technique. Numerical experiments show the efficiency and improvement of the coherent network with a nonuniform aperture over uniform, with an advantage in average equal to 1.8dB of directivity and -2dB of side lobe level. Moreover, the simulation results exhibit an aperture reuse and complexity reduction of the proposed coherent network configuration compared with a conventional antenna array with direct feeding, where each main beam is shaped and steered with the half of control signal inputs.