Formulation of the Singular Integral Equation Technique for General Planar Transmission Lines

The singular integral equation technique is used to determine the normal modes of propagation in general planar transmission lines. Taking fin-lines as example it is demonstrated, how high-order modes can effectively and accurately be calculated. Some of these modes show an unusual evanescent nature for certain combinations of parameters. The modes of this type exist always in pairs with their squared propagation constants being complex conjugate.