MODELLING OF THE MECHANISMS OF ELECTROMAGNETIC FIELDS INTERACTION WITH HUMAN BODY

Telecommunications

The interactions of electromagnetic waves with the human body are complex and depend on several factors related to the characteristics of the incident wave such as: frequency, intensity, modulation and polarization, the proprieties of the tissue encountered (geometry, electrical properties: dielectric permittivity and conductivity), the type of coupling between the field and the exposed body and the duration of exposure. The irradiating field generates currents inside the body at extremely low frequency, and energy absorption in the tissues in RF and microwave range. Specific Absorption Rate (SAR) is the quantity that measure the rate of change of the e nergy transferred to the biological tissue. At a certain level of the irradiating field, the absorbed energy can cause heating of tissues and organs; this effect is well known as thermal effects. Another so-called non-thermal effect refers to the fact that biological effects can exist below the levels which produce the thermal effects. The great puzzle here is firstly, whether radiation at such low levels can cause harmful biological changes without a confirmable thermal effects, and secondly, whether such effects can occur from electromagnetic fields radiation when thermoregulation maintains the body temperature at the normal level despite the electromagnetic energy deposition, or when thermoregulation is not challenged and there is no significant temperatu re change. In this article we will detail the mechanisms of interactions of electromagnetic waves with the human body from its sources, the propagation and zone of exposure, the penetration of the waves into the biological tissue, the mechanism of interaction with the tissue and the corresponding possible biological effects.

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