Butler Matrix Based Multi-Beam Base Station Antenna Array

In this paper, a three-beam Butler matrix as well as its antenna arrays is presented for cellular base stations. The three-beam Butler matrix is able to generate three beams in the azimuth plane, which can increase the capacity of base stations. Striplines are used for developing the 3 × 3 Butler matrix, which is compose of directional couplers and phase shifters. To extend the 3 × 3 Butler matrix to a 3 × 5 one, unequal power dividers are also require. To verify the beam-forming network, 5-element dual-polarized antenna arrays covering LTE band are developed. Multiple beams are obtained by feeding the antenna array with the augmented 3 × 5 Butler matrix. The design is verified by both simulation and experiments.