Study of high-frequency electromagnetic transients radiated by electric dipoles in near-field

The study investigates transient electromagnetic (EM) radiation in the near-field zone of a system of electric dipoles and the usage of the plane wave spectrum (PWS) concept for extraction of a 3-D field from 2-D measurements. Both aspects are important in the modelling and characterisation of radiated emissions in electromagnetic compatibility applications, which are extended here to time domain. Analytical expressions for a set of dipoles excited by short-duration Gaussian pulses, which in the author's approach are used to model EM radiation, are presented and implemented into a Matlab program to calculate the time-dependent distributions of the three electric field components E-x(t), E-y(t), E-z(t). These results are then used to verify the new technique of extraction of the time-domain component E-z(t) of the electric field from measurements of the two other components, E-x(t) and E-y(t). The details of the technique, based on PWS method applied to the time domain, are presented. Very good agreement between the extracted and analytically calculated fields has been achieved. Further verification and comparison has been done by the simulation in the time domain of the system of dipoles using commercial 3-D EM software.