Compact Wideband Butler Matrix Network Using Microstrip Structure

Abstract

In this paper, a wideband miniaturized $4\\times 4$ Butler matrix feed network is designed, which mainly includes 3dB directional couplers, cross junctions and 45° phase shifters. The Butler Matrix network has the the fractional bandwidth of 25% at the center frequency of 800 MHz. As the size of the coupler is reduced by half, the size of the Butler Matrix is more compact and can be adapted to more practical applications.