A Wideband Planar Differential Antenna Loaded with Metasurface

This paper reports a novel wideband differential antenna based on metasurface. It consists of a differential slot coupled antenna and a planar metasurface. Planar metasurface is composed of 4 × 4 elements, and a rectangular slot is embedded on the ground plane to couple energy between the differential feeding lines and metasurface. The feeding line employs the three-line coupled lines which could provide wideband filter-integrated feature. The lower and upper resonant frequencies of the proposed antenna can be adjusted independently by tuning the distance of the metasurface units and the length of the rectangular slot in metallic ground, respectively. Moreover, a differential dielectric resonator antenna is simulated for performance comparison. It is concluded that the proposed antenna has many advantages, such as low profile (0.08λ0 at 5 GHz), frequency independent, high-gain, and symmetrical radiation pattern, comparing with the differential dielectric resonator antenna. Furthermore, a differential metasurface-based antenna prototype has been fabricated to experimentally validate the principle and design approach. The measured impedance bandwidth with odd mode reflection coefficient below − 10 dB is 19.35% from 4.76 to 5.78 GHz. Meanwhile, the measured boresight gain at 5 GHz is 6.4 dB, and low cross-polarization level could be achieved.