Filtering Chiral Particle for Rotating the Polarization State of Antennas and Waveguides Components

Here, we present a compact component for waveguide systems and horn antennas, enabling both filtering and polarization rotation capabilities. In particular, the proposed module consists of an electrically thin-chiral particle, which is first used to design a waveguide twist to connect two waveguide sections mutually rotated by 90 degrees. We show that around the resonant frequency of the particle, good transmission efficiency between the two mutually orthogonal waveguides is achieved. Then, the same module is inserted at the throat of a vertically polarized horn antenna to rotate its polarization plane and narrow its matching bandwidth. The result is a filtering horn antenna that, within the operating bandwidth of the particle, efficiently radiates a horizontally polarized field. The effectiveness of the proposed module is verified through numerical and experimental results.