V-Band Geodesic Generalized Luneburg Lens Antenna With High Beam Crossover Gain

Abstract

Quasi-optical beamformers provide attractive properties for antenna applications at millimetre-wave frequencies. Antennas implemented with these beamformers have demonstrated wide angle switching of directive beams, making them suitable as base station antennas for future communication networks. For these applications, it is essential to ensure a high beam crossover gain to provide a robust service to end users within the steering range. Here, we propose a geodesic generalized Luneburg lens antenna operating from 57 to 67 GHz that provides increased crossover gain compared to previously reported geodesic Luneburg lens antennas. The focal curve of the generalized Luneburg lens can be displaced from the beamformer, allowing for a higher angular resolution in the placement of the feed array along the focal curve. The lens is fed with 21 ridge waveguides with an angular separation of 5.1 degrees, thus providing beam steering in a 102-degree range. The peak realized gain varies from 19 to 21 dBi throughout the steering and frequency ranges and the beam crossover gain is roughly 3 dB below the peak gain. The simulations are experimentally validated.

Wide-Angle Beam-Switching Antenna with Stable Gain Based on a Virtual Image Lens

“…Table 1 compares the proposed lens antenna with the reported wide-scanning planar lens antennas with stable gain. Available simulated results indicate that the gain is more stable in the presented antenna compared to the antenna based on a collimated lens [20]. In fact, the gain stability in the antenna with a collimated lens is inherently limited by the beam correlation.…”

“…The issues stemming from the beam correlation can be overcome by using two apertures, as proposed in [18,19], but the resulting antenna is bulky. The low gain between beams in rotationally symmetric lens antennas can be overcome by displacing the focal arc from the beamformer [20]. However, as also observed in the reflector-based antennas, closely spaced beams that share an aperture can suffer from performance degradation due to the beam correlation, which limits the obtainable gain stability.…”