Electromagnetic Model of Circular-Rectangular OMT

The junction shown in fig.1 is the most important part of the ortomode transducer (OMT) in the antenna feed. Until now such junctions are experimentally designed because theoretical method of analysis is not available. This approach let´s design OMT with bandwidth of 10% but we are developing theoretical model to enlarge bandwidth up to 15-20%. The electromagnetic model of this junction is based on the formulation of integral equations in the spectral domain. In this domain there are some advantages of calculus with respect to the spatial domain. The method produces a number of infinite equations with inflnite unknown variables. The coefficients of these variables are fast convergent series. The model doesn´t consider the meniscus effect at the junction. This assumption is consistent with the usual geometry of OMT junctions where the geometrical parameters of the waveguide determine very small menisci.