PEC-PMC Baffle Inside Circular Cross Section Waveguide for Reduction of Cut-Off Frequency

A design and position of a baffle placed inside a circular waveguide is presented which leads to the lowest possible cutoff frequency. The reduction in the cutoff frequency is achieved by having one side of the baffle be PEC while the other is PMC. The introduction of PMC boundary conditions leads to unique eigenvalues for the dominant mode resulting in 66% reduction in the cutoff frequency compared to that of a circular waveguide with a baffle with PEC surfaces on both sides and 41.7% reduction in the cutoff frequency compared to that of an empty waveguide. An e
^jωt
time convention is used.