High-Gain High-EIRP D-Band Planar Array Fed by Gap-Waveguide Quasi-Optical Multi-Reflector Multi-Port Architecture

Journal article, 2026

This work addresses the challenges associated with realizing a fixed-beam, high-gain, and high-EIRP (Effective Isotropic Radiated Power) planar array for D-band backhaul and fronthaul systems by proposing a novel quasi-optical multi-reflector, multi-port feeding architecture in a two-dimensional (2D) parallel-plate waveguide that enables uniform excitation of a long-slot array. The feeding architecture comprises a 2×2 array of offset 2D reflectors, each illuminated by an H-plane sectoral horn directly connected to a Tx/Rx module. A novel reflect-ortruncation-joint technique is proposed to mitigate the field-strength drop in the interface region between adjacent reflectors, thereby achieving uniform illumination along the long radiating slots. To experimentally validate the designed D-band array prior to active system integration, a gap-waveguide-based 1:4 power divider is employed to excite the four H-plane sectoral horns. A gold-plated prototype is fabricated using CNC machining and evaluated through measurements. The measured results show good agreement with simulations, achieving a peak realized gain of 39.5 dBi with antenna efficiency of 80% and a reflection coefficient below −10 dB over a 4.8% bandwidth of 139–146 GHz. This work offers a scalable pathway to high-EIRP systems while maintaining a fully planar compact form, and significantly reducing conductive loss when feeding large apertures compared to conventional corporate-feed networks.