Time‐domain reciprocity theorems for electromagnetic fields in dispersive media

Time-domain reciprocity theorems of the time-convolution and the time-correlation type for electromagnetic fields in linear, time-invariant, and locally reacting media are discussed. Inhomogeneous, anisotropic, and arbitrarily dispersive, both active and passive, media are included. The analysis is entirely carried out in space-time, without intermediate recourse to the frequency or the wave vector domain. The application to inverse source and inverse constituency (or inverse profiling) problems is briefly indicated.