A Ridge Gap Waveguide 4×4 Butler Matrix for Multibeam Application

This work presents a planar full metallic ridge gap waveguide (RGW) 4x4 Butler Matrix for 5G applications. The 4 x 4 Butler matrix is composed of 3dB couplers, cross couplers and phase shifters, operating from 24 to 28 GHz with return loss and isolation both better than 15dB. At 26 GHz, the transmission coefficient is -6 dB +/- 0.7 dB, and the output phase distributions are +/- 45 degrees and +/- 135 degrees. The proposed beam forming network (BNF) is a good candidate for 5G communication system and can be easily scaled to higher frequency bands.