A stable high-gain cavity-stacked antenna array with compact high-order mode fed for W-band applications

This paper presents a W-band stable high gain 2 × 2 cavity-backed slot antenna array fed by compact high-order mode substrate-integrated cavity (SIC) with substrate-integrated waveguide (SIW) technology. The antenna element incorporates a 2 × 2 subarray of cross-shaped slots, excited by a high-order mode (TE₂₂₀) SIC, ensuring uniform amplitude and balanced phase to achieve stable high-gain and high efficiency. Moreover, an additional SIW cavity is stacked above the 2 × 2 cross-shaped slots, incorporating a rectangular slot etched on the surface of the SIW cavity for radiation to further enhance the gain. This novel architecture yields a gain enhancement of 2.6 dBi compared to the traditional unstacked SIW cavity antenna. A prototype antenna array, consisting of 2 × 2 radiation elements and a low-loss 1-to-4 SIW power divider integrated with waveguide (WG) to SIW transition, is designed and fabricated in standard PCB technology. The measured results exhibit a −10 dB impedance bandwidth range from 91 to 97 GHz, a peak gain of 18.5 dBi, and a peak aperture efficiency of up to 78 %.