On localized antenna energy in electromagnetic radiation

Abstract

—We provide a general and rigorous formulation of antenna localized electromagnetic radiation energy in generic antenna systems based on Poynting flow instead of the spectral approach proposed earlier. The main theory is first developed using the principles of energy-momentum conservation and the center-of-energy theorem, culminating in the derivation of a direct localized energy expression. It is rigorously established that this expression satisfies the main features expected of physical energy, mainly positive definiteness and regularity. The obtained formula involves only the radiated fields (no current or charge) source and is easier to compute using specialized direct time-domain EM solvers. The proposed approach is expected to play a role in understanding energy localization in coupled antennas and shed light on gain enhancement methods.