Abstract: The ends of two strip transmission line substrates which meet at an interface are supported by resting on top of a sandwich structure made up of a dielectric, a circular metal choke member and a conductive pedestal. The choke member, the dielectric and the ground planes of the substrates form a low-loss RF ground connection to bridge the gap at the interface. The choke member, the dielectric and the ground planes form a quarter wave open circuited transmission line stub in the form of a circular structure. This structure acts as an RF choke and reflects a short circuit into the region between the ground planes, making a virtual connection between the ground planes and the metal choke member. The strip transmission line substrates and the metallic choke member are not rigidly connected, thus allowing for relative movement between the substrate and choke member due to differences in thermal expansion or contraction.

Abstract: 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 in the ridge provide a series inductance which can be optimized with the shunt capacitance of the ridge to provide a characteristic impedance matching that of the unloaded structure. The corrugated ridges provide increased differential phase shift per unit length. The differential phase shifting structure is particularly well suited to such applications as circular polarizers, quarter wave plates or polarization rotating half-wave plates.