Analysis of the tapered discontinuity in a planar dielectric waveguide

A rigorous approach yielding high accuracy is proposed for the solution of the tapered discontinuity in a planar dielectric waveguide. The method models tapered portion as a sequence of step discontinuities to which the mode-matching technique is imposed extending over infinite range. Partial field is established for TE wave polarization. An iterative procedure is developed to track the fields in forward and backward directions to obtain a higher degree of accuracy. The validity of this approach is checked by comparing the results with those of other method. The parameters of surface and radiation waves are investigated in detail. The radiation pattern exhibits no occurrence of a discontinuity in the region near the elevation angle of 90 degrees.