Nonreciprocal devices in open‐boundary structures for millimeter‐wave integrated circuits

Although a number of components for millimeter‐wave integrated circuits based on an open dielectric waveguide have been proposed, little has been reported on nonreciprocal devices and no significant results have been obtained. In this paper we discuss experimental verification of nonreciprocal propagation phenomena in an open ferrite waveguide and their application to open nonreciprocal devices. Based on the results, we propose a circulator of directional coupler type which makes use of nonreciprocal propagation phenomena in an open ferrite waveguide. We also propose a pillbox resonator type circulator and a junction type circulator using the nonreciprocal resonance of an open cylindrical ferrite. Circulators of the directional coupler type and the pillbox type do not need any conductor in principle. The radiation loss can be reduced without significant increase of the conductor loss if a conductor shield is used in the E‐plane of the junction circulator. A junction circulator with practical characteristics is developed for millimeter‐wave integrated circuits.