Propagation Constant in Tapered Segment of Slotted Rectangular Waveguide

The paper investigates the propagation constant inside the rectangular waveguide, which has a narrow longitudinal slot on its broad face, while the width of waveguide linearly changes. The propagation constant is the result of solving the dispersion equation composed by means of Galerkin method for the tangential components of magnetic field, which is obtained on the basis of dyadic Green's functions. For the description of internal region the cylindrical coordinates system is introduced so that the faces of tapered segment of waveguide coincided with the coordinate surfaces. The dependencies of the propagation constant are obtained for various values of slot length and the waveguide expansion coefficient. The results of theoretical calculations are confirmed by the results of electrodynamic modeling in ANSYS Electronics Desktop.