Dispersive effect of UWB pulse on human head

In this paper, the SA(Specific Absorption) distribution in a human head, exposed to wideband pulse EMF(0.03-3GHz), has been analyzed by taking into account the dispersion characteristics of biological tissues. The dispersive properties of biological tissues are characterized by the 4^th Cole- Cole model. However, there is no dispersive FDTD algorithm to implement the 4^th Cole-Cole model accurately. Thus, most of the current commercial simulators adopt the approximate Debye model, which can be easily incorporated into the FDTD calculation engine. Recently, new methods to implement the 4^th Cole-Cole model approximately have been proposed which utilize either z-Transform, or sums of exponential functions, or rational functions of polynomials. In this paper the FDTD methods with the dispersive algorithm for the 1st Cole-Cole model, the 3^rd Debye model and the 4^th Cole-Cole model were applied for SA analysis of four different kinds of human head exposed to a wideband pulse signal. To implement the dispersive models, each dispersive model has been optimized to the 4^th Cole-Cole model for the given frequency band. The effects of dispersion in each head model have been analyzed, and the error of each dispersion algorithm has been investigated.