The Time-Domain Optical Theorem in Antenna Theory

A special form of the time-domain optical theorem related to a general receiving antenna system is rigorously derived. It is shown that the total energies dissipated in the antenna load and in the antenna system itself can be directly related to the electromagnetic energy of the scattered field and its time-domain far-field characteristics. A practical implication of the result in optimizing antenna scattering properties with regard to the maximum energy dissipated in the antenna loading is discussed.