A Slot Array Antenna With Single-Layered Corporate-Feed Based on Ridge Gap Waveguide in the 60 GHz Band

This paper presents an <inline-formula> <tex-math notation="LaTeX">$8\times 8$ </tex-math></inline-formula>-element slot array antenna with single-layered corporate-feed based on the ridge gap waveguide (RGW) technology in the 60 GHz band. As is well known, a corporate-feed slot array antenna usually has backed cavities to increase the bandwidth and provides a space for its distribution network, and therefore three layers in total: one layer for radiating slots and two layers for feed network with one layer of back cavities and the other one of power dividers. The antenna in this paper is designed by utilizing only two separate metallic layers–a corporate-feed network layer and a radiating slot layer. Compared with the conventional three-layered slot array antennas, the proposed antenna avoids the utilization of the backed cavity layer so that its complexity and manufacture cost decrease. In order to solve the problem of the narrow bandwidth caused by taking away the backed cavities, we utilize double-ridged radiating slots instead of the conventional rectangular ones. A compact transition power divider from standard waveguide WR-15 to the RGW is introduced to excite the proposed array antenna. The <inline-formula> <tex-math notation="LaTeX">$8\times 8$ </tex-math></inline-formula>-element slot array antenna has been fabricated by computerized numerical control machining technique. The measured results demonstrate that the −10 dB reflection coefficient has around 17% bandwidth covering 56.5–67 GHz frequency range, and the measured gain is better than 26 dBi with more than 70% antenna efficiency over 58–66 GHz.