BUTLER MATRIX MINIATURIZATION FOR 5G COMMUNICATIONS AND BEYOND

Abstract

This capstone project presents a miniaturized implementation of Butler’s beamforming array on microstrip technology. Firstly, the basis of size reduction is obtained by developing a structure that behaves exactly as the quarter-wave transmission line segment at the operation frequency. Secondly, this structure is applied to reduce the area of higher-order components such as 3dB hybrid coupler and crossover. Then, the components are assembled into the layout of Butler Matrix where several components are reduced in size further. The obtained final structure takes up approximately two times less area at the cost of 20% theoretical bandwidth reduction. A 4-by-4 experimental setup is developed for validation at 2.5 GHz which corresponds to the lower 5G frequency band.