A Method for Determining the Envelope of Induced Electric Field on a Simple Human Head Model by Peaks Detection

This paper is on the use of a hybrid boundary element method/finite element method (BEM/FEM) to determine the induced electric field in spherical human head models exposed to high-frequency plane electromagnetic (EM) wave. The geometrically simplified models include the homogeneous one and the non-homogeneous one, featuring compartments such as skin, skull, CSF, and brain. Both models are illuminated by plane EM wave at frequencies including 900 and 1800 MHz, 3500 MHz pertaining to 5G communication systems and also 6000 MHz representing the transition frequency related to the EMF safety standards. The numerical results for the electric field induced in both human head models are presented, while the emphasis is on the electric field along the propagation axis. The novelty of this work is related to the subsequent post-processing of the sampled induced field along the model axis by using two different numerical filtering techniques. It is shown that using the peak detection algorithm, the spline interpolation could be used to estimate the signal envelope. The exponentially decaying nature of the envelope allows to assess the penetration depth of the EM radiation within the biological tissue. Moreover, it is shown that the analytically calculated penetration depth, derived for the unbounded medium, is well reproduced by the numerical computation of EM field.