Numerical and experimental methods applied to human exposure to electromagnetic fields

The research focuses on a hybrid experimental-numerical technique, based on Boundary Element Method (BEM), to reconstruct the electromagnetic eld distribution in the space surrounding unknown sources, in both low and high frequency range. The same procedure also allows to evaluate the induced electric eld non-invasively when human body presents near such sources. By applying BEM (including Green function) to a discretized surface that enclosing the sources, the electromagnetic elds outside the surface (source free region) can be received from an integration of same quantities over this surface. At low frequency range (up to 100 kHz), the induced electric eld inside human body can be also calculated as an inverse process, i.e. applying again BEM over a discrete body surface on which the magnetic elds are provided through the above procedure, to compute the elds at any point inside this surface. The only approximation during this procedure is assuming that on each discrete element, the eld values are uniform. Measurement can be performed on a grid with regular step over any known surfaces and both the magnitude and phase are required for each component of the electric and magnetic elds. The experimental validation at low frequency range has been carried out around a Helmholtz coil system enclosed by a wooden frame, which is used to position the 3D magnetic eld probe. Numerous eld distributions can be generated through this system by separately imposing the currents which supply the two coils, and three of them are applied in the validation procedure. The three voltage signals detected by the eld meter (corresponding to the three components of the magnetic elds) are sampled synchronously with the fourth one, which is picked up from the supply circuit and acts like a trigger, in order to compute the phases of the other three signals. The measured data is tted by an interpolation/extrapolation technique before adopted as input for BEM reconstruction in free space. Reconstruction quality through proposed BEM procedure has been investigated through dierent approaches, as well as the accuracy of the induced electric eld evaluation inside the human body. Measurement uncertainty propagation has been estimated through Monte Carlo method coupled with a discrete numerical technique. At last, the prediction of the radiation emission generated by a radio frequency model has been also presented, as an example of application for the proposed eld reconstruction in high frequency (300 MHz). A satisfactory accuracy is obtained through the comparison with another numerical method.