Compact Broadband Directive Slot Antenna Loaded With Cavities and Single and Double Layers of Metasurfaces

In this paper, a compact wideband directive metasurface (MS)-based antenna is proposed. A pair of edge-fed slots, assisted by a fictitious short, is used to excite the MS layer which is made up of a periodic arrangement of rectangular loop-based unit cells along both the x- and y-directions. The proposed MS-based slot antenna is compact and provides good matching over the entire bandwidth with a broadside radiation pattern. A metallic cavity and an artificial magnetic conductorbased cavity are integrated on the MS-based antenna to reduce its backward radiation. Finally, a pair of edge-fed slot antennas combined with two layers of MSs having compact ground plane area of 1.04 λ02 (λ0 is the operating wavelength in free space) is proposed for the improvement of gain, bandwidth, and forward radiation. The overall antenna has a low profile of 0.05 λ0. The proposed configuration shows a 21% measured bandwidth with an average gain of 9.6 dB over its bandwidth. Over its bandwidth, the antenna efficiency is >89%. The design is validated by a fullwave simulation study followed by the experimental verification.