Gain enhancement for microstrip antenna with zero-index metamaterial

A wideband microstrip antenna fed by a modified T-shaped probe is presented for 60-GHz applications. In order to improve the gain performance, a novel Zero-Index Metamaterial (ZIM) is loaded at the top of the proposed antenna. The zero permittivity point of the proposed ZIM structure is acquired at the frequency around 60-GHz. Two antennas are simulated for a comparison, the antenna loaded with ZIM cells and the one without ZIM cells. The antenna loaded with ZIM cells exhibits a gain enhancement of up to 3.1dB in the frequency band of 55–70 GHz. The impedance bandwidth for SWR≤2 is about 30% from the frequency band of 55–70 GHz.