Radiators in Time Domain–Part II: Finite Pulses, Sinusoidal Regime and Q Factor

In part I, closed form expressions were derived in time domain to calculate the electric and magnetic field energy around a device and the energy radiated by the device. In part II, these expressions are applied to cases important in practice: pulses finite in time domain, and sinusoidal regime. The time domain expressions are able to provide a deeper physical insight compared to the previously derived equivalent expressions in frequency domain. The solution proposed by Gustafsson and Jonsson to solve the issue of “negative energies” can be interpreted based on them. This leads to an upgraded calculation of Q factors. The new expressions are illustrated through numerical calculations for the two most basic radiator types: dipoles and loops.