This article presents low-profile configurations of the Fresnel zone plate antenna at Ka-band. The investigation involved progressively reducing the focal distance of the antenna through simulations and observing the effect on the directivity, radiation patterns, and aperture efficiency. The number of metal zones was also varied in the simulations. It was found that focal distances below 0.75λ yielded little more directivity than the feed itself. With a single zone, the 1.25λ focal distance achieved the highest overall aperture efficiency of 24%, which was a significant improvement over the larger focal distance cases. Measurements were performed to verify the simulated results.

Microwave and Optical Technology Letters
Department of Electronics

Stout-Grandy, S.M., Petosa, A., Minin, I.V., Minin, O.V., & Wight, J. S. (2008). Investigation of low-profile fresnel zone plate antennas. Microwave and Optical Technology Letters, 50(8), 2039–2043. doi:10.1002/mop.23593