Beam forming network design for cluster feeding of scanning antenna

This paper proposes a new beamforming network (BFN) for a scanning antenna system that generates a steerable beam using a reflector illuminated by an array of feeding elements. This BFN comprises several variable phase shifters, a power divider, and a Butler matrix (FFT circuit), which is a multibeam matrix network, and forms a primary beam pattern by using the Fourier transform. This BFN can obtain a primary radiation pattern that is very similar to the input signal distribution of the beam port, and does not require deep consideration of the excitation distribution of the antenna elements to obtain the desired pattern. Moreover, the beam pattern generated by this BFN effectively illuminates only the reflector. We confirm that this BFN was able to improve the antenna efficiency by 11%.