Design and Development of an Efficient Rotman Lens Beam former for the Applications of 5G and Beyond

Abstract

With the development of 5G and beyond applications, there is an increased demand for high data rate communication. High band allocations up to mm-waves ensure these high data requirements. Among different beamforming structures, the Rotman lens (RL) is an attractive passive microwave lens-based beamforming network due to its low cost, reliability, design simplicity, and wide-angle scanning capabilities. Conventionally, RL is implemented using micro strip lines (MSL) technology for which there are inherent high atmospheric absorption and path losses which become severe for the applications operating at these high frequency bands. To mitigate these losses, high gain and narrow pencil-like beam radiation patterns are preferred for the applications operating at mm-Wave frequencies. So, for 5G and beyond applications, there is an increased demand for more efficient, directional and wideband beamforming devices. In this context, a novel fabrication technology i.e., Substrate Integrated Coaxial Line (SICL) is used for the first time to design the RL which provide accurate beamforming with the lowest possible radiation losses. This thesis presents a complete design development and performance analysis of SICL based RL beam former for the applications of 5G and beyond. By using SICL, isolation between the ports up to 15 dB is achieved which ensure a good impedance matching between the input beam ports. Due to the use of low-loss SICL technology, a high gain up to 13 dBi is achieved with an excellent scanning capability of -30 to 30 degrees over a wide frequency band of 24 to 28 GHz with 26 GHz as the central operating frequency. Owing to the low-loss and high gain performance, the designed SICL RL is suitable to be used for mm-Wave applications.