The equivalent circuit with an ideal transformer for waveguide junctions

Rigorous electrodynamic calculation of different end waveguide junctions with infinitely thin diaphragm shows that as a rule, the real part of input conductivity depends on aperture dimensions, therefore an equivalent circuit of an end waveguide junction can not be represented in the form of reactive conductivity in the joint plane of two transmission lines with different wave resistances. An equivalent circuit of the end waveguide junction is shown to contain reactive conductivity and an ideal transformer. The transformation coefficient value is determined by the ratios of aperture dimensions to dimensions of waveguides and does not depend on frequency. Expressions for transformation coefficients are obtained for some waveguide junctions.