Modeling of discontinuities on lossy planar microwave structures by the spectral domain approach

New components appear, that require an improvement in the modeling methods in the microwave field. Indeed, in order to model the working of components such as the photoelectrical switch, whose substrate conductivity varies under the action of a judiciously chosen light beam, it has proved that taking losses in 3D problem was required. Thus, we have coupled the complex frequency concept to a dynamic modeling method: the spectral domain approach. This concept lays on the fact that the resonance frequency of a lossy resonator is complex. It enables to get the quality factor of the resonator and then its equivalent circuit, including the resistive elements that are characteristics of the losses. In the case of low losses, this general principle can be used through a perturbation method. We develop here this principle and use it for the study of a photoelectrical switch.