Effects of substrate material and dielectric properties on electromagnetic energy absorption over GSM bands

This paper analyzes the effects of electromagnetic (EM) absorption towards human head with variations of human head dielectric properties. The human head exposed to 900, 1800 and 1900 MHz operational frequencies. Specific absorption rate (SAR) was the parameter used to measure the interactions of EM waves towards human head. The mobile phone attached with helical antenna together with human head simulated through finite-difference time-domain (FDTD) method using Computer Simulated Technology (CST) Microwave Studio. The human head dielectric properties were varied with increment and decrement of 10 % and 20 % of each of the properties. Through this study, it was found out that conductivity was directly proportional to SAR values while permittivity was inversely proportional with SAR values. In all frequency exposures, helical antenna with substrate of FR4 resulted in the highest SAR values. It was found that, helical antenna with substrate of Rogers RO3006 (loss free) had contributed the lowest SAR values in all operational frequencies exposed.