Three dimensional modelling of EM fields in the human head

Public unease about the possibility of biological effects from the close proximity of RF fields due to the widespread use of cellular handheld transceivers together with the introduction of the new DECT 1700 MHz systems has spurred research into modelling and measurement of field strengths in human tissue. In particular given the location of the antenna in a handheld telephone, the brain, ears, eyes and hand are of particular interest since they are all in close proximity to the radiator. Using a two dimensional model Dilworth (1993) showed that some focusing of fields occurs in the human head from a close proximity antenna such as in the case using a handheld telephone. The present authors apply a three dimensional transmission line model to the problem. In the case of the two dimensional model the dimensions of an anatomically averaged human head were used and the dielectric values involved were taken from well established data. For the 3D model, for convenience, the authors use an elliptical head approximation and, unlike the 2D model, because of the limited mesh size applied they ignore bone, blood, muscle and other detail and assume a homogenous dielectric constant for the brain