A Compact Butler Matrix Design Based on Metallic Nanowire Filled Membrane Technology and Tunable Phase Shifter at 160 GHz

This paper presents the design of a planar miniaturized 4x4 Butler matrix, with implementation of 4 tunable 135° delay line phase shifters for a 160 GHz application. The Butler matrix and phase shifters are both realized with a metallic nanowire filled alumina membrane (NaM) technology, using slow-wave microstrip line to miniaturize the size. Tunability is achieved by filling in a microwave liquid crystal. Comparing with commonly used corporate feed network, the simulation results show such a Butler matrix with 135°-phase shifters has less insertion loss and reduced size.