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°. 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.