Consideration of Poynting Localized Energy Around Radiators: An FDTD-based Investigation

In this paper, we focus on the Poynting Localized energy around arbitrary radiating systems, which is fundamentally different from the antenna reactive energy. By utilizing the FDTD-computed near-zone electric/magnetic fields around any antenna (multi-band/wide-band, not necessarily electrically small), it is possible to evaluate the Poynting localized energy density for various temporal excitations (Gaussian pulse/gated sinusoidal signals). Using the proposed FDTD-based scheme, we analyze the localized energy behaviour around microstrip-fed slot-loaded printed dipoles. We re-examine the impedance matching issues and redistribution of localized energy, caused by perturbation of antenna parameters, and obtain insights not available from the traditional circuit-theoretic Q-factor approach.