Initial design and optimization of broad-band and dual-band square-to-circular waveguide transitions

This paper presents guidelines for the design of square-to-circular waveguide transitions. Based on an algorithm developed for rectangular waveguide transformers, performances of initial and optimized transitions are presented. Although a direct transition from square to circular waveguide provides already a reasonable return loss, it is shown that more sections are required for broad-band and dual-band transitions. Verification of design and analysis procedures is provided through comparison with the commercially available field solver HFSS.