| Summary: | 碩士 === 國立臺灣科技大學 === 電機工程系 === 91 === This thesis investigates the specific absorption rate (SAR) of the human body caused by the electromagnetic waves radiating from a mobile phone used by the person. A finite difference time domain software package XFDTD and the electromagnetic constitutive parameters of the human body are applied to analyze the electromagnetic effects between the mobile phone and human body and to evaluate the SAR in the human body.
In those studies, accurate simulation structures for analyzing the SAR are developed first, which include models of the human body and the mobile-phone handset to reduce simulation errors. Then, simulations and analyses are performed for the second generation (2G) GSM900/DCS1800 mobile communication system, which is popularly used in Taiwan. Typical exterior and interior antennas for the commercial mobile phones are simulated to evaluate the effects of different antenna structures on the SAR. Further, the SAR simulations for the third generation (3G) W-CDMA mobile communication system to be employed in the near future are studied. On the other hand, due to the effects of the dielectric materials in the human body, the characteristics of the antennas near the human body are different from those in free space. Thus, the influences of the human body on the antenna characteristics of the mobile phone are studied, which include radiation efficiency, input impedance, bandwidth, gain, and directivity.
As to the mitigation of the SAR values for the mobile phone, this thesis presents two approaches: one is the applications of the electromagnetic absorbing materials and the other is an interior antenna design for the mobile phone. Also, the SAR values excited by using an ear phone are studied. The secondary radiations from the connecting wire of the ear phone may increase the SAR values of the human body near the connecting wire. The uses of the electromagnetic absorbing materials on the surfaces of those metal objects may mitigate the secondary radiations and then reduce the SAR values in the human body.
This study is quite valuable for practical applications. Patent applications in Taiwan and other countries have therefore been submitted for many new solutions presented here.
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