A multibeam circularly polarized antenna array based on miniaturized Butler matrix network

In this paper, a circularly polarized microstrip antenna array based on a beamforming network is designed. The beamforming network is a miniaturized 4×4 microstrip Butler matrix. The antenna array operates at 2.41~2.47GHz with S11<-10dB. Gain of the antenna array is greater than 8.7dB which axial ratio is less than 3 dB in the width of the main lobe. The antenna array can form four beams with about 40° spacing in a plane.