Abstract: A mode suppressor structure designed to maintain TE.sub.01 mode matching in an overmoded waveguide, while at the same time allowing efficient coupling of unwanted modes for dissipation in the mode filtering structure of the overmoded waveguide, and in a manner which is non-intrusive on the TE.sub.01 mode and thus promotes high power operation.

Abstract: A sharp, mode-transducing bend structure for circular TE.sub.01 overmoded waveguide systems is formed by first transducing from circular TE.sub.01 waveguide into multiport rectangular TE.sub.10 waveguide, performing the desired bend, and then transducing from the multiport rectangular TE.sub.10 waveguide back into the circular TE.sub.01 waveguide.

Abstract: A dominant TEM mode and a pair of spatially orthogonal TE.sub.11 modes suitably excited at the input ports of a coaxial waveguide commutator portion of a coaxial waveguide commutation feed network are employed to generate a commutatable low-sidelobe amplitude distribution at symmetrically disposed peripheral output ports of the coaxial waveguide commutator. The resulting low-sidelobe amplitude distribution can be used to feed radiating elements of an associated circular phased array antenna. The coaxial waveguide commutator is configured, inter alia, with a linearly tapered inner conductor surrounded by a uniform tube outer conductor to achieve a smoother TEM-dominant mode characteristic impedance transition from the input port plane to the output port plane thereof. Employment of this feed geometry, in conjunction with balanced four-port feeding of the coaxial waveguide commutator which inhibits the higher order TE modes, increases the bandwidth capability while maintaining low insertion loss.