Ultra-Wideband Low-Profile Waveguide Antenna Array with High Aperture Efficiency

This paper presents an ultra-wideband, low-profile, full-metal waveguide antenna array based on quasi-TEM mode radiators, an ultra-wideband rectangular-coaxial-to-ridge-waveguide transition, and an air-filled corporate feeding network using rectangular coaxial lines. The antenna is fully metal and fabricated through computer numerically controlled (CNC) machining and laser cutting, ensuring high precision and minimal conductor loss. The measured results show excellent agreement with the simulations, validating the effectiveness of the design. The proposed antenna achieves a fractional bandwidth of 105% (10–32 GHz), an aperture efficiency exceeding 90%, and a profile height of 0.3λ at the lowest frequency. The antenna minimizes grating lobes while ensuring uniform power distribution across the array. Experimental verification confirms its wideband impedance matching, high gain, and stable radiation characteristics over the wide frequency range.