Extremely High-Scanning-Rate Slot Array Antenna Employing Uniplanar-Coupled Waveguide Cavities

In this letter, we propose an extremely high-scanning-rate slot array antenna utilizing uniplanar-coupled waveguide cavities, allowing for easy fabrication and a low-profile planar implementation. In contrast to the current technique employing an alternating electric and magnetic coupling topology, the proposed new architecture relies on a combination of pure-magnetic coupling topology and phase reversal radiators, which allows high-scanning-rate beam scanning around the broadside. We design and fabricate both metallic waveguide and substrate integrated waveguide implementations to showcase the effectiveness of the proposed technique. Experimental results demonstrate that the two uniplanar-coupled waveguide antennas can scan angle ranges of 65<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^{\circ }$</tex-math></inline-formula> and 70<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^{\circ }$</tex-math></inline-formula>, respectively, within a 40 MHz frequency band centered at 4 GHz (equivalent to a 1% bandwidth). Compared to state-of-the-art methods, these proposed frequency-scanning antennas exhibit exceptionally high scanning rates, ease of fabrication, and a low-profile implementation.