Comparative Study of Wideband Butler Matrix and Rotman Lens Beamforming Network for Millimeterwave Applications at Ka Band

Abstract

This paper investigates two low-cost beamforming network approach for millimeter-wave and 5 G applications at frequency band of 27 to 40 GHz. As a result, an 8×8 Butler matrix and an 8×8 Rotman lens are developed. Both beamforming network have similar physical sizes and have return loss less than -10 dB. In comparison with the Butler matrix, the Rotman lens has better and more stable insertion loss, it also has less deviation in the phase shift in between the output ports. Prototype of the beamforming networks are fabricated. Experimental validation results together with further comparisons such as array factor and scanning angles will be presented in the conference.