Analysis and Design of Circular Waveguide Polarizers with Elliptical Irises

A new design of a polarizer realized in circular waveguide with the insertion of short lengths of guide with elliptical cross-section is introduced. The new structure, that requires a manufacturing by milling techniques only, compares favourably with circular waveguide implementations, since it is composed only by waveguides with separable cross-section, hence producing a definite advantage in electromagnetic modeling. With respect to previously known solutions using square waveguide sections it has the intrinsic advantage of avoiding the rectangular-to-circular transition when the component is used, as customary, with a circular feed. Measured and theoretical results for a polarizer with a 90° ± 1° differential phase shift over the operating 7.75-8.55 GHz band show a very good agreement.