Hamid Khodabakhshi

  PhD Thesis Defense Session

  Abstract:

  In recent years, the rapidly increasing use of mobile phone operating nearby the human head has caused public concern for the effects on human health. In this thesis, after studying of general considerations of biological effects of electromagnetic waves, a new analytical method has been introduced to analyze the interaction between a six-layered lossy spherical human head model and a half-wave dipole antenna. In this method, a simple form of quasi-Green's function for a six-layered lossy sphere has been presented based on the sommerfeld integral. The method of auxiliary sources was then applied to model the half-wave dipole antenna. In the numerical results, the antenna radiation patterns and the local SAR have been calculated at 900 and 1900 MHz. In the second section, a fast numerical simulation of the human head coupling with a PIFA structure based on the CIE/MoM approach to study the effects of the EM coupling on the antenna performance. A mix-potential integral equation (MPIE) for the surface current of the PIFA and volume electric field integral equation (VEFIE) for the head have been extracted. After finding the antenna current distribution, the antenna performance parameters such as input impedance, radiation patterns and radiation effeciency have been calculated. Finally, simulation of mobile phone with dual-band patch antenna in the vicinity of the anatomical model of head has been performed using FDTD methodology. Then, the electric field, local SAR and 1gr-averaged SAR distribution have been calculated at 900 and 1800 MHz. Thereafter, temperature-rise of head tissues due to the radiation of mobile phone has been estimated using the bio-heat equation. It was observed that the peak of the temperature-rise in the brain region is very lower than the allowable values of temperature-rise in the brain tissue. To validate the proposed method, the mobile phone in the proximity of the spherical head phantom has been simulated and the results have been compared with the results of XFDTD and CST softwares.

  Defense Date: Wednesday 20/11/1389 Time: 16:00

  Place : Electrical Engineering Department, Room 305