Design of Ridge Waveguide Radial Combiners

This article presents a comprehensive treatment to the subject of designing ridge waveguide radial combiners. A theoretical framework for the design process is first presented paving the way to a straightforward design procedure for radial combiners with both moderate and very wide bandwidths (BWs) realized in ridge waveguides. Two types of ridge waveguide radial combiners are presented, one with linearly tapered ridged sections and the other with staircase-like ridged sections. The methodology to design the radial combiner is presented. It starts with designing the individual ridge waveguide input ports, and then designing an equivalent transformer section that provides matching between the individual ridge waveguide ports and a common coaxial line output port. Design considerations for the different cross sections make it possible to achieve the required impedance levels for good matching across wide BWs. Three complete design examples are presented. Two proof-of-concept prototypes were designed, simulated, fabricated, and tested demonstrating excellent measured results without any tuning.