A Broadband Gain-Enhanced Conical-Beam Antenna Loaded With the Multicircle Sectored Metasurface

A broadband gain-enhanced monopole antenna loaded with metasurface is designed in this article, which is suitable for sub-6-GHz fifth-generation (5G) applications. The multicircle sectored metasurface antenna is analyzed through the evolution process and field distribution. With the addition of the metasurface, the antenna’s relative bandwidth is increased from 23.25% to 48.5%, and the in-band gain is improved by 2 dBi. To validate the proposed working principles and design guidelines, the proposed antenna is fabricated and measured. Measured results agree well with the simulated ones and show that the −10-dB impedance bandwidth is 56% (3.25–5.78 GHz), covering the 5G frequency band (3.3–3.6 and 4.8–5 GHz). The average gain in the desired band is 7 dBi with a variation of ±1 dBi, which is suitable for 5G indoor microceiling base station applications.