Design and characteristic mode analysis of a low-profile wideband patch antenna using metasurface

A low-profile linearly polarized patch antenna using metasurface is proposed for wideband operation at 5-GHz Wi-Fi bands. The antenna is comprised of a rectangle patch sandwiched between a lattice of 3x3 periodic metasurface and the ground plane. The adopted coaxial probe feed is easy to fabricate and match. Characteristic mode analysis (CMA) is utilized to explain and understand the working mechanism of the proposed antenna. It is found that two dominant characteristic modes are well excited, leading to the broadband operation and linearly polarized radiation. The proposed dielectric-filled antenna with a low profile of 0.057 lambda(0) (lambda(0) is the operating wavelength at 5.7GHz in free space) attains about 30% measured -10 dB impedance bandwidth (4.89-6.62 GHz) with 7.28 dBi average gain. Across the bandwidth, the antenna efficiency is greater than 90%, and cross-polarization levels are less than 18 dB.