Non-Reciprocal Mode Converting Substrate Integrated Waveguide with Unsymmetrical Perturbation

In this work, we have proposed and developed a special non-reciprocal waveguide in which forward and reverse directed waves propagate in different paths, like a two-way road that traffic in each road flows only in one direction. This waveguide structure is made possible thanks to the use of a substrate integrated waveguide loaded with anti-symmetrically biased twin-ferrite slabs. Further, this structure has been exploited to design a compact, fully integrated, non-reciprocal mode converting waveguide device, which converts the TE10 mode into TE20 mode only in one direction while in the reverse direction the mode is preserved all along the propagation. Finally, a new type of circulator that operates on the basis of the proposed nonreciprocal mode conversion mechanism has been designed, fabricated and measured to validate and highlight the whole theoretical foundation of this work.