High-gain UWB double slot vivaldi antenna loaded with metasurface and semi-elliptical slots

In this work, an ultra-wideband double slot Vivaldi antenna (DSVA) loaded with a novel wideband nonresonant metasurface is proposed to enhance the gain. The semi-elliptical slots are etched on both sides of the ground plane of the DSVA to improve the current distribution. In addition, the nonresonant metasurface composed of WiFi-shaped unit cells could maintain a stable high refractive index in the operating bandwidth of 1−18 GHz, which could bend the outgoing wave to the end-fire direction. Both the original antenna and the proposed antenna are simulated, fabricated, and characterized. The measured results are in good accordance with the simulated ones. The return losses of both antennas are less than −10 dB in the frequency range of 2−13.4 GHz, while the gain of the proposed antenna is improved from 13.6 to 16.3 dBi with a maximum gain enhancement of 3.1 dB.