Dual-Band Advanced Short Backfire Antenna With 100% Aperture Efficiency Over a Wide Range of Diameters

In this article, we demonstrate that a circular advanced short backfire antenna (A-SBFA) can be optimized for high single- or dual-band aperture efficiency over a range of different aperture sizes. Optimization methods developed previously to utilize anisotropic, dispersive metasurfaces on the cavity walls of the hexagonal A-SBFA are modified and applied to achieve 100% aperture efficiency at two frequency bands for circular aperture diameters spanning a remarkably large range from 1.0\lambda _{0} up to 2.13\lambda _{0} . Furthermore, a single-frequency optimization was able to achieve a design with 100% aperture efficiency for an A-SBFA with a diameter of 2.6\lambda _{0} , the highest known achievable efficiency for an antenna of its aperture size, and overall height. Finally, simulations revealed the first compact hard horn or open-ended waveguide design with close to 100% aperture efficiency below 1.6\lambda _{0} .