Low-Profile Conical-Pattern Slot Antenna With Wideband Performance Using Artificial Magnetic Conductors

A slot antenna with conical patterns and wideband performance based on artificial magnetic conductors (AMCs) is presented in this paper. It has four symmetrical square radiating slots and a meandered feeding network etched on the both sides of the upper substrate to achieve a compact size. Wideband performance is achieved by tuning the resonant frequencies of the one-wavelength slot and quarter-wavelength monopole modes close to each other. The electric fields generated by these four slots cancel each other, resulting in a radiation null in the center. And the AMC surface converts the radiation pattern into conical pattern. The simulation and measurement results on S
₁₁
, radiation patterns, efficiencies, realized gains, and SAR values are given. The performance of the proposed antenna in a practical helmet model is studied. The results show that the proposed antenna has an impedance bandwidth of 4.83-6.25 GHz (1.42 GHz, 25.6%), maximum gain of 6 dBi at the elevation angle of 36°, and low 1 g SAR values of less than 0.22 W/kg for the application of the IEEE 802.11a WLAN system.