Investigation of Time-Averaged Poynting Localized Energy Dynamics around Narrowband and Ultrawideband Antenna Systems

In this paper, we investigate the spatial dynamics of the recently discovered time-averaged Poynting localized energy around antennas using a finite-difference time-domain (FDTD) analysis technique. We consider two-port antenna systems comprised of: (i) narrowband thin-wire dipoles and (ii) ultrawideband (UWB) "fat" dipoles based on circular patches. Using FDTD, we characterize the S-parameters as well as evaluate the time-averaged localized energy distribution along an observation plane for differentiated Gaussian pulse excitation. Full-wave simulation results provide critical insight into energy signature manipulation in regions between closely spaced UWB antennas by changing their relative orientations. It is found that significant departure from S-parameters-based insights is revealed in the new localized energy data generated here using our method with practical antenna types as examples.