Characterisation and modelling of near-field radiated emissions in the time-domain

The paper presents the characterisation and modelling approach for near-field (NF) radiated emissions in the time-domain based on the combination of time- and frequency-domain methods. Plane wave spectrum (PWS) transformation can be used to extract 3-D electromagnetic (EM) field from 2-D measurements as well as to calculate time-domain EM near-field at different heights above the measurement plane. As PWS applies to frequency-domain quantities, a Fourier transform is used to convert between time- and frequency-domains. The radiated emissions are modelled by an array of electric dipoles with time-domain excitations, enabling fast and easy calculation of an electromagnetic field anywhere in the surrounding space. However, identification of the dipole model parameters directly in the time-domain is difficult, so time-frequency approach is proposed. The approach has been verified by analytical calculations and 3-D EM software simulations.