On the Phase-aligned Transmission Lines of a mmWave 5G Rotman lens Based Beamformer

Multi-antenna systems along with the millimeter wave (mm-Wave) frequency systems provide a viable solution for the increased high data demands for more than one users in a cell of a communication system. Beamforming technology has been found to fulfill these high data rate demands. As compared to conventional phased array beamformers, the Rotman lens-based beamformers are one of the prominent solutions in which the phase shifter array responsible for beamforming is replaced by a passive lens providing a low complexity and a low-cost alternative. In this paper, phase aligned transmission lines, that provides a connectivity between Rotman lens structure and the array of antenna elements, are briefly analyzed. Specifically, phase and magnitude response of the insertion components of multiple lengths of phase align transmission lines is discussed. It is shown that by carefully selecting the length of phase align transmission lines of a Rotman lens, better performance in terms of low loss and accurate phase shifting can be achieved.