Circular waveguide bifurcation for asymmetric modes

An analytical solution for a circular waveguide bifurcation with incident TE11- and TM11-modes is presented using the residue calculus method. It is shown how the coupling between the TE1n- and TM1n-modes can be taken into account by expressing the coupling factor as a contour integral, which is the key step enabling the residue calculus method to be applied. Graphical results for the scattering matrix parameters of the junction are given for a range of waveguide radii of interest in the design of dual-mode coaxial prime focus feeds for paraboloidal antennas.