Beamforming for Millimeter Waves Using a Planar Fresnel Zone Plate Lens Antenna Array

Despite the effective beamforming capabilities of massive MIMO systems, their implementation in the mmWave frequency bands presents significant challenges due to complexity, cost, and high power consumption within multiple RF chains and phase shifter networks. Unlike traditional beamforming, a planar FZP lens integrated with a massive MIMO system was used to steer beams by adjusting the feed array elements on the focal surface of the lens. Two FZP lens antenna configurations at 60 GHz within ETSI V-band were designed and simulated using two different feeds: a 4×4 pyramidal horn array and an 8×8 circular microstrip patch array. Using CST Studio Suite, simulations had demonstrated that the FZP lens antenna by microstrip patch array, with optimal lens placement, significantly outperformed the FZP lens antenna by horn array. The patch array achieved 29.9 dBi gain and 2.8° HPBW, compared to 28.2 dBi gain and 8.1° HPBW for the horn array. Additionally, the compact patch design provided a wider coverage range of [-46°, 46°], supporting more users per cell. These findings demonstrate that adjusting feed elements for beam steering with optimal antenna-lens matching eliminates the need for extensive phase shifter networks, improving the performance of millimeter wave-based 5G systems.