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The dispersion and leakage characteristics of coplanar waveguides are treated using the spectral-domain approach together with the complex residue technique. To handle the complex propagation constant of the coplanar waveguide, the Fourier transform and Parseval's theorem in the complex plane are extended. A number of numerical results, such as the effective dielectric constant and normalized attenuation constant, are presented to illustrate the characteristics of the coplanar waveguide. Sharp peaks just after leakage together with broad peaks are two interesting phenomena observed in the attenuation characteristics. The physical mechanism of these peaks and the details of transition in the epsilon /sub eff/ and alpha /k/sub 0/ curves are still unclear. >

A perturbed-transverse electromagnetic (TEM) approach to studying the detailed current distribution and the propagation constant of a multiconductor transmission line system with imperfect conductors is discussed. The perturbed fields are derived assuming that the fields outside the conductors are TEM waves of the corresponding lossless system and those inside the conductors satisfy the transverse magnetic (TM) modal equations. These fields are then inserted into a perturbational formula to obtain the propagation constant of the lossy system. The current distribution and the propagation constant (which clearly illustrates the loss mechanism due to the skin effect and the proximity effect) of a lossy two-wire system are presented as an example. >