Gain Enhancement of 60-GHz Antipodal Tapered Slot Antenna Using Zero-Index Metamaterial

A zero-index metamaterial (ZIM) structure is proposed for the gain enhancement of an antipodal tapered slot antenna (ATSA) at 60-GHz bands. The single ATSA loaded with the proposed ZIM cells exhibits a gain enhancement of up to 2.6 dB in the frequency band of 57-66 GHz. A prototype of a two-element ATSA array loaded with the ZIM cells measures a |S
₁₁
| of less than -10 dB and gain of 12-13.2 dBi over 57-66 GHz. The measurement results agree with the simulated ones and the gain enhancement of the ZIM cells is confirmed.