Wire and patch method of moments models of coaxial to arbitrary waveguide transitions

We present a study of different techniques for the accurate characterization of coaxial to waveguide transitions. The methods use the integral equation technique to calculate the currents induced on the walls of the waveguide and on the coax probes. The modeling of the coax probes is carried out using two models, namely a thick wire model, and a surface model using triangular cells. The symmetry of the junction is exploited by using images with respect to ground planes of electric and magnetic types. Results show that the thick wire model is accurate for moderately thick probes (a/λ = 0.025), while the rigorous surface approach must be used for probes with larger radius.