Field mapping within biological tissues at millimeter wave frequencies

The universal personal communication system age is coming soon and significantly more knowledge is needed on the interaction of electromagnetic fields with the human body in the millimeter-wave band, particularly in the 20-60 GHz frequency range. Since electromagnetic energy deposition in the human body in this frequency range is superficial (skin, eyes, etc. ...), a study has been initiated using a modified version of the Finite Difference Time Domain method (FDTD) expanding grid algorithm to determine Specific Absorption Rate (SAR) distributions. These distributions were obtained using a homogeneous dielectric sphere as a simplified skin-equivalent model of the human head at 20 GHz and 30 GHz, consecutive to a plane-wave exposure. A correct formulation for the absorbing boundary condition is given. Subsequently, the effect of bringing the absorbing boundary within the dielectric body is considered and results are discussed