Multigrid FDTD code for calculating microwave absorption pattern in human head radiated by hand-held antennas

Numerical modeling of realistic engineering problems using the finite-difference time-domain (FDTD) technique often requires more details than are possible when using a uniform-grid FDTD code. With the increasing interest in the FDTD method, and the desire to extend modeling to more complex structures. The use of the uniform-grid FDTD algorithm becomes prohibitive due to limited computer resources. We describe the application of a three-dimensional multigrid FDTD code in describing the microwave power absorption distribution in a realistic model of a human head exposed to radiation from a hand-held antenna. With the multigrid FDTD code it is possible to focus a large number of cells of small dimensions in the head region, and the rest of the body is modeled using coarse cells. The proposed procedure makes it possible for the first time to take into account the effect of the rest of the human body on the absorption characteristic in the head and the radiation pattern of the antenna. It is shown that this effect is particularly important when antennas are placed at a relatively larger distances from the body. Body shapes and dimensions also play an important role in determining the radiation characteristics of these antennas.