Equivalent circuit model of square waveguide T-junction for ortho-mode transducers

In this paper, an equivalent circuit model of square waveguide T-junction is derived from numerical results obtained by mode-matching analysis. The resultant 5-port network is simplified as a combination of a 3-port network and a 2-port network. A short-circuited branch ortho-mode transducer (OMT) is then designed in circuit simulator using this equivalent circuit model. Measured results exhibit good agreement with those from circuit simulation.