A Steerable Dual-Polarized Monopulse Reflector Antenna With Gap-Waveguide Adaptive Phase Shifters for E-Band Backhaul

This letter presents an E-band monopulse feed with broadband gap-waveguide adaptive phase shifters for Gregorian reflector antennas tailored for 5G backhaul communications. The monopulse functionality is achieved using a gap-waveguide-based 2 × 2 step-horn-array feed with a feeding network comprising 3dB couplers and adaptive phase shifters. The antenna achieves an ultra-high-gain of 50 dBi through integration of the feed with a Gregorian reflector antenna and employs beam steering by offsetting the feed from the sub-reflector focus. However, the feed offsetting degrades the null depth in difference (Δ) patterns. Therefore, a new phase compensation strategy is proposed, involving a co-design of adaptive phase shifters with the offset by using a numerical phase compensation function quantified in this work based on simulation data through GRASP and CST. The fabricated antenna demonstrates reflection coefficients below −10 dB for both polarizations over 71 − 86 GHz. Measured radiation patterns and gains align closely with the simulated. The system achieves a maximum gain of 50.48 dBi, with beam steering within ±2 ° from boresight and a maximum steering loss of 0.96 dB. The null depth of all Δ-beams is maintained above 20 dB. These results highlight the significant potential of this antenna for 5G backhaul communications