A Broadband Metasurface with Voltage-Controlled Transmission Phase

In this paper, an active four-layer metasurface using varactors is proposed which has 0° - 360° tunable transmission phase range and higher transmission magnitude than 0.8 with the large relative bandwidth about 12%. The capacitance of varactors is changed through the biased DC power, hence the transmission phase of the metasurface enables to shift continuously in an easier way, compared to the switch diode-based metasurface and digital metasurface. This work offers a valuable strategy to design broadband dynamically-tunable metasurface and has a good potential for high gain phased antennas and efficient beamforming.