Broadband pressure barrier for circular waveguide

A broad passband waveguide/pressure barrier arrangement comprising:

• a fixed radius circular waveguide for transmitting radio frequency (RF) energy in a spatially circumferential field mode between a source and a receiver;
• a solid cylindrical plug region formed of a dielectric material and sealed in a cross-section of said circular waveguide and having a longitudinal thickness for blocking the passage of a predetermined pressure load, said plug region centered on a radial plane of said circular waveguide;
• a plurality of solid cylindrical tuning regions formed of said dielectric material, said plurality of solid cylindrical tuning regions consisting of pairs of identically sized tuning regions, each pair having a unique radius and a longitudinal thickness, each pair being arranged symmetrically in mirror image fashion about said radial plane in order of decreasing radius, said plurality of solid cylindrical tuning regions coaxially aligned with said plug region in a contiguous abutting relationship;
• and
• each said radius and said longitudinal thickness of said plurality of solid cylindrical tuning regions, and said longitudinal thickness of said solid cylindrical plug region, sized so that an input impedance of a combination of said solid cylindrical plug region and said plurality of solid cylindrical tuning regions as seen from the source is equal to a characteristic impedance of said circular waveguide for a passband of interest.