Coaxial waveguide diplexing circuit using a corrugated waveguide transition

A technique using corrugated-wall waveguide to separate the energy from two frequency bands into concentric coaxially disposed circular waveguides is discussed. The corrugation depth is chosen so that the reactance sign of the surface impedance changes between the two frequency bands. This has the effect of matching the respective field distributions fo the coaxially disposed waveguides. A unique low-pass filter added fo the coaxial waveguide supports the center conductor and further enhances the isolation between the two frequency bands.