Downsized left-handed waveguides with ridge-shaped stubs

This paper suggests two types of structures for downsizing left-handed (LH) waveguides. One is composed of two waveguides stacked on their common broadside with virtual series capacitive stubs in ridged waveguide structure. The other is constructed of a single folded waveguide with the virtual capacitive stubs of a half-mode ridged waveguide in the interior conductive plate inserted for folding a rectangular waveguide. Good points of the present LH waveguides are simple structure and low-loss nature in addition to compactness. The validity of the design concept is confirmed by a commercial em-simulator.