Electrically reconfigurable waveguide polarizer using liquid crystal technology for Ka-band applications

A broadband liquid crystal based polarizer is presented in this paper, electrically changing the orientation of the fundamental TE₀₁-mode of a square waveguide. The basic concept is similar to the twisted nematic cell in LC-display technology, however, adapted to the microwave regime as a waveguide component. This allows for continuous, electrical reconfiguration of the linear polarization from -90° to 90° with respect to the incoming mode. Besides the demonstration of the prototype, methods for implementation are shown regarding the optimal length for the maximum crosspolarisation suppression. The polarizer has an insertion loss of about 6 dB to 7 dB between 28 GHz and 40 GHz.