Wideband Linear-to-Multi-Polarization Converter Based on Active Metasurface

This article proposes a transmission-type linear-to-multi-polarization converter based on cascading four-layer metasurface integrated with p-i-n diodes. By controlling the states of the p-i-n diodes, the polarization maintaining (PM) which means transmission without conversion, linear to linear (LTL), linear to right-hand circular polarization (LTRCP), linear to left-hand circular polarization (LTLCP) conversions can be realized. When the PM is realized, the incident wave will pass through the polarizer with low loss over wideband, the isolation is higher than 30 dB. When the linear-to-circular polarization (LTCP) conversion is realized, the incident linearly polarized (LP) wave can be converted to a left-hand circularly polarized (LCP) or right-hand circularly polarized (RCP) wave with a relative bandwidth over 40%. When the LTL polarization conversion is realized, the polarization conversion ratio (PCR) is greater than 0.9 from 2.58 to 3.89 GHz. The overlapping bandwidth of the four operating states is 36%. The detailed design process and equivalent circuit of the proposed polarizer are analyzed in this article. A sample consisting of
$10\times10$
elements is fabricated. The measured and simulated results are in good agreement. To the authors’ best knowledge, this is the first reported reconfigurable polarizer capable of PM, LTLCP, LTRCP, and LTL polarization conversions within wideband. The proposed device can play an important role in polarization diversity and RF-integrated aperture of wideband channel multiplexing technology.