INVESTIGATION ON THE SPECIFIC ABSORPTION RATE (SAR) IN A 3D HUMAN HEAD MODEL EXPOSED TO ELECTROMAGNETIC RADIATIONS

Abstract

Exposure human tissue to electromagnetic radiation (EM) from radio wireless frequencies causes many
negative health effects. The assessment of the absorbed EM by human tissue depends on the Specific
Absorption Rate (SAR) factor. In this paper, a square patch antenna (SPA) is designed to be a source of
EM radiation, and optimized to operate at several applicable frequencies, such as GSM 1800, IEEE 802.11
WLAN standard 2.4 GHz and 5.3 GHz bands, and 3.2 GHz WiMAX band. The radiated EM by the SPA
antenna is evaluated in a 3D human head model or Specific Anthropomorphic Model (SAM), which
consists of two layers, the outer shell (1.5 mm thickness) and filled with tissue simulating liquid (TSL).
The investigation involved four aspects, first the distance between the SAM and the EM source has been
moved between 0 mm to 50 mm, second for the specific distances (0 mm, 15 mm, 30 mm, and 45 mm) the
frequency of EM source has been changed among 1.8 GHz, 2.4 GHz, 3.2 GHz, and 5.3 GHz. Third, the tilt
angle (θ) between the SAM and the antenna has been shifted from 00
to 900
. Finally, the antenna
encasement (2 mm thickness plastic material) was removed and the procedure in the first step is repeated
to investigate the effect of encasement on the SAR reducing. The results reveal that there is an inversely
proportional relation between SAR and distance, SAR and tilt angle. Besides, the antenna encasement has
a large impact on attenuating SAR value, while the SAR is directly proportional to frequency. All SAR
evaluations were performed by CST-2014 Microwave studio simulator which is built on the
Finite-Difference-Time-Domain (FDTD) principle. All calculations are achieved over 1 g and 10 g of mass
tissue averaging and according to IEEE/IEC 62704-1 standards.