Influence on electromagnetic field of both time-varying medium in waveguide and its boundaries

An analysis of the electromagnetic transients caused by elementary action of both a time-varying medium and its boundary is given with a representative example of an oblique incidence of a plane monochromatic wave onto the flat boundary of a medium whose permittivity changes abruptly in time. This action significantly changes the scenario of the electromagnetic process, since the transient accompanies the transformed field, in contrast to the case of the normal incidence of the wave when the transformed field consists of monochromatic secondary waves only. The paper investigates the influence of a sequence of such elementary actions on the electromagnetic field in a dielectric waveguide whose permittivity changes in time by jumps. It is shown that these actions can form a basis for the modelling of electromagnetic processes in waveguides with a nonlinear medium.