An iris polarizer in coaxial waveguide

An accurate and reliable electromagnetic model has been developed for the design of a circular polarizer in a coaxial waveguide. The component consists of a coaxial waveguide loaded by irises with inductive and capacitive behaviors for the incident field. The design is based on the method of field expansion into eigenmodes and takes into account the effects of higher order mode interactions and of multiple reflections among the polarizer elements. The measured and computed performances of a very compact five-element feasibility breadboard are presented. An axial ratio better than 1.02, insertion losses lower than 0.1 dB, and return losses better than 27 dB have been obtained over a 13.5% frequency band.<>