Gain enhancement of a multiband square-loop patch antenna using an AMC-PEC substrate and a radome

In this paper, a high gain tetra-band microstrip patch antenna fed by a modified L-shaped strip has been designed, simulated and measured. The antenna consists of three concentric square-loop patches to support four operating modes and cover WLAN/Bluetooth, WiMAX, Mobile/Fixed satellite services, and WLAN/V2X commercial applications. In order to enhance gain of the antenna, the incorporating effect of the antenna with a superstrate and an artificial magnetic conductor (AMC)-perfect electric conductor (PEC) ground plane is investigated. It is demonstrated that the antenna gain is enhanced significantly when the superstrate is placed over the AMC-PEC ground plane based antenna. It shows a realized gain of 10.1 dBi at the first frequency band and achieves an increase in the gain by 7.5 dB. One outstanding result of the proposed design is that the air thickness between the square loops and the superstrate is about λ/40, because of the AMC-PEC ground plane. The proposed antenna has a low profile with overall dimensions of 0.64λ×0.64λ×0.08λ for the frequency at 2.42 GHz. A prototype of the antenna is fabricated and tested to verify the design.