The Finite-Difference Time-Domain (FDTD) is the most often used method for
evaluation of electromagnetic fields in human tissue. This is of particular
importance for compliance testing of portable telephones. The specific abs
orption rate (SAR) averaged over 1 or 10 g tissue mass is required by regul
ations not to exceed a prescribed value. A computer algorithm is developed
for post-processing the FDTD data. This algorithm can be used for uniform a
s well as graded meshes, while the required cubical shape is maintained. Ex
tensive investigations are shown of the resultant SAR due to the number of
electric field components used in field averaging, and the volume of air wi
thin the cube. The latter is easily controlled in the algorithm, but the re
gulations on the permissible SAR do not specify it at the present time.