Aperture efficiency improvement using metasurface

A method to improve the aperture efficiency of antennas using a non-uniform metasurface (MS) is studied in this paper. For illustration, a patch antenna and a planar MS having unit cells of square patches with different sizes are used. The sizes of the square patches on the MS follow a radial gradient index function. The aperture efficiencies of the patch antenna and the antenna using the MS are compared. For easy comparison, the patch antenna is designed to have an aperture size of λ
₀
×λ
₀
, where the λ
₀
is wavelength at the operating frequency in free space. Simulation results show that, by placing the MS atop the patch antenna with a separating distance of 35 mm, the directivity of the patch antenna can be increased from 9.7 dBi to 11.6 dBi. With the aperture size remains unchanged, the aperture efficiency of the patch antenna is increased by more than 100%.