A coordinate transformation method is introduced to effectively solve the problems of traditional methods in the numerical simulation of irregular waveguides. According to the form-invariance property of Maxwell's equations under coordinate transformations
the coordinate transformation can be realized by means of an equivalent anisotropic medium whose constitutive parameters are obtained from the Jacobian tensor of the coordinate transformation. By employing the proposed method
an irregular waveguide can be transformed into another regular waveguide filled with appropriate anisotropic medium without changing its propagation characteristics. Thus
the analysis to an irregular waveguides can be replaced with the analysis to the transformed regular waveguides with easy numerical implementation. The proposed technique can largely reduce the complexity of the boundary processing algorithms and the number of unknowns
hence effectively enhances the computational performance. Simulation results on an elliptical waveguide and a ridged rectangular waveguide show that the proposed method can ensure enough calculation accuracy and reduce computing resources by about 50%.
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