Realistic Air-Filled TEM Printed Parallel-Plate Waveguide Based on Ridge Gap Waveguide

A double-ridge and double-sided textured surface waveguide based on the printed ridge gap waveguide (PRGW) is introduced. The structure acts as a parallel-plate waveguide supporting TEM waves, and it is referred to as TEM-PRGW. The TEM-PRGW has lower insertion loss and more confined power around the double ridges in comparison with the single-textured PRGW. The characteristic impedance of the TEM-PRGW is extracted from the conventional parallel-plate impedance expression. The TEM-PRGW is symmetric around the middle horizontal line splitting the gap. The modified unit cells of the periodic structure around the double ridges are also introduced to improve the TEM-PRGW performance in the presence of any discontinuities along the propagating direction, which might excite undesired horizontal polarization. Prototypes of the straight and double bend lines are fabricated based on the modified unit cells to prove the concept and have confidence in the simulation results.