Terminating Junctions in Single Layer Feed-waveguide for Excitation of the Dominant Quasi TEM-wave in Oversized-rectangular Waveguide

This paper proposes a single-layer feed waveguide with dielectric-filled matching junctions to excite a dominant quasi-TEM mode in oversized-rectangular waveguide with hard-surface sidewalls. Two coupling junctions in cascade with matching L-terminating junctions have been manufactured and the excitation of a dominant quasi-TEM mode was confirmed by both far- and near-field measurements at 12 GHz. The ripple in amplitude was less than 3 dB and in phase less than 15 deg. The bandwidth is 2.2% in terms of reflection less than -10 dB for the overall feeding structure