Mitigation of Radiation Loss in mmWave Rotman Lens Beamformers

The millimeter wave (mmWave) frequency spectrum, essential for high capacity transmission in Beyond 5G (B5G) and 6<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sup> Generation (6G) communication systems, requires efficient and precise beamforming solutions. The Rotman Lens (RL), known for its low-cost fabrication, design simplicity, wide bandwidth, and wide-angle scanning capabilities, has been extensively used in beamforming networks. Traditionally, Microstrip Line (MSL) technology is employed to develop RL. However, MSL-based RL suffers from considerable radiation losses in addition to insertion losses due to impedance mismatch. The radiation loss is prominent at mmWave frequencies, which degrades the RL performance. To overcome these challenges, the Substrate Integrated Coaxial Line (SICL) technology offers an improved alternative for RL development, making them highly effective for beamforming and multiplexing operations. This paper discusses the design challenges and performance of SICL-RL, to study enhanced phase accuracy, and wide-angle scanning capabilities for mmWave applications.