End-Fire Surface Wave Antenna With Metasurface Coating

This paper describes a wideband and low-profile end-fire surface wave antenna embedded into a large metallic platform. It consists of a tapered grounded slab fed by a wideband surface wave launcher and coated with a planar gradient metasurface (MS). It is found that by altering the surface reactance of the MS array, the surface wave propagating in the grounded slab can be manipulated to suppress the radiation of TM₁ mode region at a specific high frequency. A simple design procedure of MS array is then developed. In addition, a blind-filled cylinder hole is used to further improve the radiation pattern at certain high frequencies. A prototype of the proposed antenna is finally fabricated and tested. Measured results are in good agreement with simulated ones, and they show that the surface wave antenna has a very wide bandwidth from 3.78 to 18.54 GHz for voltage standing wave ratio < 2.5 and exhibits a low profile of only 5 mm (<inline-formula> <tex-math notation="LaTeX">$0.063~\lambda _{L}$ </tex-math></inline-formula>, <inline-formula> <tex-math notation="LaTeX">$\lambda _{L}$ </tex-math></inline-formula> is the free-space wavelength at the lowest operating frequency). Good radiation pattern and high gain are achieved over a wide frequency band.