ACCURACY OF BLOCK-MODELS FOR EVALUATION OF THE DEPOSITION OF ENERGY BY ELECTROMAGNETIC-FIELDS

Numerical solutions were found for block models using as many as 3048 cubes to approximate a prolate spheroidal model of man at 100 and 225 MHz. A high-frequency modification of G. W. Hohmann's (1974) formulation (HFH) gave values of mean absorption within 5% to 7% of those with the iterative extended boundary condition method (IEBCM). Arrangement of the cells for a best-fit approximation of the spheroid is found essential for such high accuracy. Numerical quadratures using the cubical shape of the cells verified the high accuracy of the closed-form expressions used for HFH matrix elements. Quadratures over spheres having the same volume as the cells gave inaccurate values for the matrix elements. Values of average absorption calculated with 296, 560, 1376, and 1944 cell models of the prolate spheroidal model of man differed from each other by no more than 17% at frequencies of 10 to 400 MHz, and by 5. 0% at the resonant frequency of 75 MHz.