75dBm EIRP W-band Electronic 2-D Beam-steering Antenna Integrated with a GaAs Array Transmitter via Quasi-Optical Spatial Power Combining

Journal article, 2026

We present a W-band (92–96 GHz) electronically steerable reflector antenna system for 6G backhaul that cointegrates a GaAs multi-channel transmitter (Tx) with a compact waveguide focal-plane array (FPA) via a quasi-optical multi-input feeding network (QOFN). Unlike conventional architectures that separate power amplifier (PA) power combining and beamforming into distinct modules, or switch a single PA among QOFN inputs, the proposed QOFN simultaneously combines the power of all PAs while synthesizing the required FPA excitation for electronic beam steering. This eliminates a separate lossy switch/combiner stage and equalizes per-channel power, critical for maintaining high Tx efficiency. Methodologically, we develop an active-system modeling framework that extends conventional passive antenna array formulations by incorporating PA output mismatch effects, channel-to-channel variations, and discrete phase-shifter states into the beam synthesis. The formulation yields closed-form realized-gain and EIRP (Effective Isotropic Radiated Power) maximization solutions under realistic PA constraints. To compensate for mast swaying, a rim-extended offset parabolic reflector is co-designed with the FPA, providing ∼ 50 dBi gain with ETSI Class 3 sidelobe mask compliance over a 2-half-power-beamwidth 2-D steering range. A prototype with six Tx PAs shows that across 92–96 GHz and multiple beams, the minimum measured EIRP is ≥ 75 dBm, the on-axis beam reaches ∼ 80 dBm, and the QOFN insertion loss is 2.3–3.7 dB. The results experimentally validate a unified architectural and modeling approach to high-EIRP W-band backhaul transmitters, demonstrating a compact and scalable alternative to large silicon-based phased arrays that typically peak near 60 dBm EIRP.