Rectangular Waveguide Radial Combiners Based on Curvilinear Matching Sections

This paper presents an innovative configuration for a compact non-resonant rectangular waveguide radial combiner. The combiner design relies on a curvilinear profile of its matching sections and successfully matches the frequency dispersive rectangular waveguide ports to a TEM coaxial line. The structure then enables the common TEM coaxial line port to feed standard rectangular waveguide port thus avoiding bulky mode converters. The proposed design promises to be useful in applications where compact size and high power handling are of high importance. The design methodology takes advantage of the inherent symmetry in the structure and uses a curvilinear surface described by a third order polynomial to design for a minimum reflection coefficient at the common coaxial port. This is followed by designing a compact coaxial to rectangular waveguide transition. Two designs are presented as proofs of concept. A design was fabricated and tested demonstrating very good results.