| With rapidly increasing demand for wireless communication, wireless handsets such as cellular and cordless telephones have been widely used. Electromagnetic exposure of a wireless handset near human head is a major public concern. Wireless handset as a low power transmitter can make human head super-irradiated due to the induction and radiation field of the antennas of the handset. The microwave energy which is absorbed by human body may induce thermal and non-thermal effects that may lead to damages to human body. Specific Absorption Rate (SAR), which is based on the electric field within the exposed body, is a key evaluation index for such exposure accepted by most of the international standard organizations.The dissertation, articulates my researches on evaluation for electromagnetic exposure of wireless handsets, the effects of head size on the electromagnetic energy absorption, the design of antennas for RFID handsets and its key technology, are based on electromagnetism, antenna theory, computational electromagnetism and Exposure Assessment of RF Technologies. These researches results not only provide effective inquiry data for RF bioeffects study, but also make a guiding role for the green design of wireless handsets.The main efforts and contribution of this dissertation are as following:(1) The confidence interval of E-field probes calibration for a high level of confidence is derived from Monte Carlo method. The compression characteristic of Schottky detector diode causes E-field probes highly non-linear over signal strength. Therefore it is important to accurately calibrate E-field probes in simulation liquid at mobile communications frequencies before probes are used in dosimetric measurements. The Monte Carlo method uses the probability density function rather than the mean, standard deviation and degree of freedom. So it avoids the approximation in the evaluation of uncertainty of probe calibration in Guide to the Expression of Uncertainty in Measurement.(2) The SAR distribution in a SAM head model which induced by a planar inverted-F antenna are studied by simulation and measurement. The PIFA antenna is widely applied to mobile service in which the 900MHz frequency band and 1800MHz frequency band are the current carrier frequency bands in China. The impacts to human health are investigated using the finite-difference time-domain technique. Assessments of specific absorption rate in the head were conducted through simulating the energy absorption mechanism of head in the near field. The experimental results are in good agreement with the simulative results.(3) A novel antenna and feed networks are proposed for a dual frequency of 840MHz～845MHz and 920MHz～925MHz application which is allocated for radio-frequency identification (RFID) use in China. Due to enhanced bandwidth, the antenna can also be applied to ultra high frequency of 860MHz-960MHz that is proposed for RFID use by ISO/IEC. The feed networks which are used to attain circular polarization characteristics of the antenna were introduced. Simulation and measurement were performed and the frequency band with a return loss less than -10dB was achieved. The evaluation for electromagnetic Exposure of the antenna is discussed in details.(4) Electromagnetic exposure of a mobile phone near children's head which is compared with adult's head is investigated by using finite-difference time-domain method. The factors which cause variation of the results in previous research as are evaluated by Numerical simulation. We focus on the effects from different relative positions of mobile phones, the effective distance between the antennas and the human head, normalization of numerical simulation. The thesis results are important and can work as a foundation to conduct further research in green design for wireless handset.
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