A Reconfigurable Broadband Polarization Converter Based on an Active Metasurface

• Published in: IEEE transactions on antennas and propagation Vol. 66; no. 11; pp. 6086 - 6095
• Main Authors: Gao, Xi, Yang, Wan Li, Ma, Hui Feng, Cheng, Qiang, Yu, Xin Hua, Cui, Tie Jun
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.11.2018; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Active metasurface; Bias; Broadband; Broadband antennas; Circuits; Circular polarization; Computer simulation; Conversion ratio; Converters; Diodes; Electric potential; Electronics; Equivalent circuits; Metamaterials; Metasurfaces; P-i-n diodes; Polarization; polarization conversion; reconfigurable; Reconfiguration; Strips; Switches; varactor; Varactor diodes; Varactors; wideband
• ISSN: 0018-926X; 1558-2221
• DOI: 10.1109/TAP.2018.2866636

We propose an active metasurface whose functionalities can be dynamically switched among linear-to-linear, linear-to-elliptical, and linear-to-circular polarization conversions in a wideband. The active metasurface is composed of butterfly-shaped unit cells embedded with voltage-controlled varactor diodes. By controlling the bias voltage of the varactor diodes, the electromagnetic responses of the proposed metasurface can be tailored, leading to reconfigurable polarization conversions. The simulation results reveal that with no bias voltage, the proposed metasurface is able to reflect linear-polarization waves to cross-polarization waves in the frequency range from 3.9 to 7.9 GHz, with a polarization conversion ratio of over 80%; however, at the bias voltage of −19 V, the metasurface is tuned to be a circular polarization converter in a wideband from 4.9 to 8.2 GHz. Moreover, two equivalent circuits along the <inline-formula> <tex-math notation="LaTeX">x </tex-math></inline-formula>- and <inline-formula> <tex-math notation="LaTeX">y </tex-math></inline-formula>-directions are developed to elucidate the tunable mechanism. The experimental results are in a good agreement with the simulation results obtained from commercial software and from the equivalent circuit model.