Novel unified mode matching analysis of concentric waveguide junctions

A novel unified mode matching technique is proposed for the calculation of the modal scattering matrix of concentric waveguide junctions. The TE and TM modal fields in both waveguides which are connected to form the junction are expressed in the Cartesian coordinate system, so that the coupling coefficients of all the modes can be evaluated effectively. All types of waveguide junction are dealt with in a similar manner and no special function is required. As examples, the scattering parameters of nine types of waveguide junction are calculated and compared with other methods or measurements in the literature. Very good agreement in all these cases demonstrates the efficiency, accuracy and flexibility of this technique