Chiral Knotted Wire Metasurfaces for Near-Reflectionless Polarization Rotation

This work investigates the asymmetrical electromagnetic radiation of chiral knotted wire metasurfaces. We start with a theoretical analysis, deriving the vector potential for a general knotted wire metasurface. It is shown that if trefoil knots are chosen, the radiated field exhibits asymmetrical radiation, and the radiated field is circularly polarized. We use these characteristics to demonstrate a near-reflectionless polarization rotation metasurface. The proposed concept is numerically simulated, where the transmission and reflection coefficients of the electromagnetic fields are calculated. The design exhibits an almost perfect transmission into the rotated polarization, with a transmission of -0.64 dB.