Expressions are derived for the induced electric fields in an ellipsoidal model of man and experimental animals irradiated by an EM plane wave when the wavelength is long compared to the dimensions of the ellipsoid. Calculations of the power absorbed by an elliptical model of man are given and simulated for six different orientations of the ellipsoid with respect to the incident plane wave field vectors. The results show that the induced fields and the absorbed power in the ellipsoid are strong functions of frequency, size and orientation with respect to the incident EM field vectors. The results for the ellipsoidal model of man are also compared with those of the prolate spheroidal model. A long wavelength analaysis of Electromagnetic(EM) plane wave has recently developed and applied to prolate spheroidal models of man and phantom models. The results of power absorbed calculations in the prolate spheroid models of man and some experimental animals show that orientation of the body with respect to the incident plane wave vectors is an extremely inportant variable which can make an order of magnitude difference in EM power absorption. This strong dependance of EM power absorption upon orientation has also been observed experimentally, and simulated. The results are encouraging. Saline solution is used to measure the EM power absorption in prolate spheroidal human phantom, to observe six different orientations. Results of the calculations for spheroidal models have been compared with measurements of power absorbed by saline-filled spheroidal phantoms and good agreement between theoretical calculations and measurements have been found. Prolate spheroidal model is suitable for small objects like(rat, mice) since for these species, cross sections taken normal to the long axis appears approximately circular. An ellipsoidal man model will be a superior representation of primates(man, monkey, and others). In this paper the perturbation technique is applied to analyze the internal fields in an ellipsoid irradiated by a plane wave for each of the six major orientations of the incident fields with respect to the ellipsoid. Expressions for average absorbed power and power distribution inside the ellipse are given. Curves of power absorption versus frequency show that the absorbed power is a strong function of size and orientation of the ellipsoid in the incident fields. The first order internal electric fields and specific absorbed power in ellipsoidal models of man and experimental animals irradiated by an EM plane wave have been obtained for the case when the wavelength is long compared to dimensions of the ellipsoid(a/λ) < 0.1. The expressions for the internal fields and specific absorbed power and the curves of specific absorbed power versus frequency show that the internal electric fields and the specific absorbed power depend on the bodies dielectric properties and geometry as well as the frequency and polarizations of the incident wave.
