Differentially-Fed Slot Array Antenna Backed With High-Order Resonating Cavity Loading Slow-Wave Top–Bottom Double Pins

A novel slot array antenna based on a rectangular waveguide (RWG) cavity using the high-order resonating mode is introduced in this article. A TE440-mode radiation cavity is used to excite <tex-math notation="LaTeX">4×4 </tex-math> radiation slot elements with a specific distribution that ensures in-phase fields. To achieve a wide 1-dB gain bandwidth, slow-wave top–bottom double pins (TBDPs) are positioned near the radiation slots within the radiation cavity. This helps to simultaneously improve directivity, impedance matching, and eliminate grating lobes. A differential feeding strategy is deployed, employing the TE120-mode feeding cavity to excite both coupling slots with identical amplitude and 180° phase difference. The measurement and simulation results of the proposed cavity-backed slot antenna are in good agreement. The measured results reveal notable achievements, including an impedance bandwidth ( <tex-math notation="LaTeX">S₁₁ < -10 </tex-math> dB) of 9% (14.2–15.54 GHz) and a 1-dB gain bandwidth of 8.05% (14.3–15.5 GHz). Furthermore, the measured peak realized gain is 18.87 dBi and the maximum realized aperture efficiency is 86.2%.