On the computation of power in VIE scattering and radiation calculations

We present simple formulas for computing power (including absorbed, scattered and radiated power) in current-based volume integral equation formulations. The proposed formulas compute the quantities of interest directly from the equivalent polarization currents and the material properties with no need for post-processing. We also discuss the application of Poynting theorem for the case of sources inside lossy materials. The effectiveness of these formulas is demonstrated by computing absorbed and radiated power in a number of representative geometries.