A Compact and High-Gain Cavity-Backed Waveguide Aperture Antenna in the C-Band for High-Power Applications

In this paper, the design of an ultracompact cavity-backed waveguide aperture antenna operating at C-band with 14% fractional bandwidth at 5.8 GHz is discussed. The measured results demonstrated a 96% antenna efficiency, greater than 78% aperture efficiency, 18 dB return loss, and 15 dBi gain with 0.6 dB flatness over the entire desired bandwidth (5.4-6.2 GHz). Measurements were found to be in excellent agreement with the simulation results. With a size of 126 mm (length) × 86 mm (width) × 48 mm (height), the proposed antenna is also ultracompact in comparison with other reported antennas with the same aperture size and electromagnetic features. The compactness of the proposed antenna was accomplished by employing a novel approach to excite the output aperture. This approach was achieved by incorporating the cavity-backed waveguide apertures and waveguide steps. The antenna structure is composed of three aluminum layers firmly screwed to each other. Each layer is manufactured by using the computer numerical control milling machine. The proposed antenna is an appropriate candidate for high-power applications due to its metallic structure and high radiation efficiency. The proposed structure is very robust and has carefully been designed to exhibit low sensitive to manufacturing tolerances.