A finite difference frequency domain method(FDFD)is presented to analyze the propagation characteristics of waveguides with imperfect conductor and rough surface. Two curl equations in the Maxwell system are discretized with difference method in the cross-section of the waveguide
and the loss surfaces and rough surfaces of the waveguide are replaced by the surface impedance boundary conditions(SIBC)and the equivalent SIBC
respectively. Then the eigen equations about the electromagnetic field components are formed and solved to obtain the propagation constants for a given frequency. Comparison with the perturbation method shows that the presented method is effective when the interested frequency is under cutoff frequency and the waveguide has irregular boundary. The simulation results show that with the increase of roughness
the attenuation constant is gradually increased to 2 times of that with smooth surfaces.
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references
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