A differential phase shifting structure is disclosed, employing corrugated ridges in square or round waveguides or in coaxial lines operating in the TE.sub.11 mode. The structure provides a substantially constant differential phase shift between two waves polarized orthoganally to each other. The corrugations...http://www.google.se/patents/US4725795?utm_source=gb-gplus-sharePatent US4725795 - Corrugated ridge waveguide phase shifting structure
