Reflection-free Transmission in Reciprocal Slot Line Waveguide

A slot line waveguide that incorporates an enclosure in the form of a perfect-magnetic conductor (PMC) is presented. The configuration exclusively supports the propagation of a quasi-transverse electromagnetic (TEM) mode that is shown to be immune to reflections associated with bends in the propagation pathway. This is due to the mode forming time-reversal symmetry-warranted pseudospin states (decoupled polarizations), which are locked to the wavevector like in photonic topological insulators (PTIs). Unlike PTIs, however, the proposed structure does not demand a periodic system with a tailored wavefunction behavior. Here, the pseudospin property is intrinsic to the quasi-TEM mode and is simply enforced by eliminating all other modes including plane waves through the use of the PMC cover. We present a proof-of-concept design and full-wave simulation results, proving attractive for numerous microwave, millimeter-wave and terahertz applications.