D-Band Demonstration of Quasi-Optical and Analog Beam Reconfiguration Using Phased Array and Lens for 6G Applications

In this article, a hybrid quasi-optic and analog beamforming approach is presented, involving an elliptical lens with an active focal plane array at D-band (110–170 GHz). Beamwidth reconfigurability and steering in two planes with enhanced performance are demonstrated. The quasi-optic technique minimizes the beam squint over frequency. Analog phase shift in the focal plane array is used to increase the lens steering range. A prototype including two four-channel D-band transceivers with on-chip antennas has been built as demonstrator. The resulting active focal plane array consists of $2\times 4$ antenna elements, which are tuned in amplitude and phase to reconfigure the beam. The advantages of using a resonant leaky wave (LW) cavity combined with a coherent array of feeds are discussed and quantified. Radiation pattern measurements performed with the calibrated active antenna validate the beam reconfiguration concept in two planes at 140 GHz. A steering loss reduction ranging from 2 to 4.5 dB is achieved in the whole D-band at 22° scan angle by applying beam steering in the feed radiation.