A reconfigurable ultra-wideband polarization converter based on metasurface incorporated with PIN diodes

A reconfigurable ultra-wideband reflective polarization conversion metasurface (RUR-PCM) is proposed. The unit cell of the RUR-PCM consists of an anisotropic metal patch incorporated with a voltage controlled PIN diode, a dielectric layer, and a metal ground. When the PIN diode is switched on, the RUR-PCM can convert an incident linearly polarized electromagnetic (EM) wave to its orthogonal counterpart; when the PIN diode is switched off, the RUR-PCM can convert a linearly polarized EM wave to a circularly polarized one. The performance of the RUR-PCM is further improved by adding the superstrate and the “double L” metal patch to the unit cell of the RUR-PCM. Simulated and experimental results show that the RUR-PCM is able to achieve linear-to-linear (LTL) polarization conversion in the frequency range of 6.5–19.9 GHz with the polarization conversion ratio higher than 90%, and linear-to-circular (LTC) polarization conversion in the frequency range of 7.6–23.6 GHz, with the axial ratio better than 3 dB. Therefore, the LTL and the LTC polarization conversion methods are integrated into one metasurface in an ultra-wideband range, and each unit uses only one PIN diode, which makes the RUR-PCM have a broad application prospect in secure communication and polarization compatibility.