Low-profile Broadband Metasurface Antenna for 5G Antenna-in-package Application

A low-profile broadband antenna is proposed in this paper. This novel antenna is composed of a $\mathrm{2}\times \mathrm{2}$ closely arranged patch array with a loaded square ring type AMC structure fed by aperture coupled microstrip line. The proposed metasurface antenna and two reference antennas are separately designed with a same total thickness of only 0.33 mm for 37/39 GHz communication. The performance of the three antennas are investigated and analyzed in detail to verify the difficulty of obtaining large bandwidth under the condition of ultra-low profile and the effectiveness of the proposed metasurface antenna scheme. The results indicate compared with the narrow bandwidth of 3.7% and low gain of 5.6 dBi for reference patch antenna, the reference patch-driven metasurface antenna can effectively improve the bandwidth and gain. But the proposed metasurface antenna achieves the best performance among three antennas with the widest bandwidth of 20.1% for |S 11 | below −10 dB and 15.6% for |S 11 | below −15 dB together with a maximum gain of 9.8 dBi. The proposed antenna with low profile and broadband features is highly recommended for 5G millimeter wave antenna-in-package applications.