Calculation of 3-D waveguide structures with EFIE

Several examples of numerical calculations of waveguiding structures for microwave devices are presented. In the calculations we used the electric field integral equation (EFIE) model, applied to infinitely thin, perfectly conducting waveguide surfaces. The method of moments (MoM) is used to transform this model into an algebraic system of linear equations. It is solved by means of an iterative procedure with fast multipole method (FMM). The solution represents induced surface current, from which the electromagnetic field in the device is obtained. With the help of this method an asymmetric mode converter TE01-TE11 was calculated and optimized for maximum efficiency. We have also calculated several multi-mode helical structures, which are planned to be used in gyro-TWT and pulse compressors, and analyzed their dispersion curves. Experiments with these components were carried out. The numerical results agree well with the measurements.