Showing papers by "Jianqing Wang published in 2003"
TL;DR: Two kinds of children's models from a Japanese adult head model are developed, based on Japanese children's statistical data on external shapes of heads, which suggest that the contradictory conclusions drawn by the above two groups may be due to the different conditions in their numerical peak SAR calculations.
Abstract: The controversy on the dosimetry in children's heads for mobile telephones is still inconsistent Gandhi's group [1996, 2002] reported a considerable increase of the spatial peak specific absorption rate (SAR) in children's heads, while Kuster's group [1998] claimed that there was not a significant difference in the SAR between children and adults In this paper, based on Japanese children's statistical data on external shapes of heads, we developed two kinds of children's models from a Japanese adult head model Using the children's head models, we calculated the local peak SAR under the same conditions as those previously employed by Gandhi's and Kuster's groups Compared to the local peak SAR in the adult head model, we found a considerable increase in the children's heads when we fixed the output power of the monopole-type antenna, but no significant differences when we fixed the effective current of the dipole-type antenna This finding suggests that the contradictory conclusions drawn by the above two groups may be due to the different conditions in their numerical peak SAR calculations
117 citations
16 May 2003
TL;DR: In this paper, a cuboid liquid phantom simulating a homogeneous human body model was used for the EMI evaluation of pacemakers by portable telephones, and it was shown that the maximum interference distance increases with the third root of the antenna transmitting power for the cuboid torso model.
Abstract: Due to the difficulty of electromagnetic interference (EMI) measurement in an actual pacemaker use situation, the recommendations for the management of health risks of implanted pacemaker users from portable telephones have been developed, based mainly on an in-vitro measuring system with a cuboid liquid phantom simulating a homogeneous human body. The validity of such a highly simplified human body model, however, has never been carefully examined. In this paper, with the application of our previously proposed numerical method for the EMI evaluation of pacemakers by portable telephones, we first confirmed Irnich's finding that the maximum interference distance increases with the third root of the antenna transmitting power for a homogeneous cuboid torso model in order to show the validity of our modeling. We then investigated whether the finding holds true for an actual human body using an anatomically based human model, and confirmed the usefulness of the simple cuboid model in the EMI evaluation for cardiac pacemakers
8 citations
01 Jan 2003
TL;DR: In this paper, the authors analyzed numerically the organ resonance characteristics in the frequency range from 30 MHz up to 3 GHz with an anatomically based high-precision human body model and a parallel finite-difference time-domain (FDTD) technique.
Abstract: It is well known that electromagnetic (EM) energy is absorbed inhomogeneously in the human body even for plane-wave exposure. This implies that local resonance for various individual organs may occur. In order to investigate this implication, we analyzed numerically the organ resonance characteristics in the frequency range from 30 MHz up to 3 GHz with an anatomically based high-precision human body model and a parallel finite-difference time-domain (FDTD) technique. As a result, we found that the whole-body resonance occurring around 65 MHz causes the local resonance for all the organs at the same frequency. Local resonance peculiar to each of organs was also found to occur around 900 GHz for the brain, eyes and heart, 600 MHz for the testicles, and so on.
6 citations
15 Oct 2003
TL;DR: Numerical results show that the maximum temperature increases in the head and brain were reasonably proportional to the peak SAR in the corresponding regions.
Abstract: We investigated the correlation between the peak SAR and the maximum temperature increase in the models of infants and adults for exposure to a dipole antenna Numerical results show that the maximum temperature increases in the head and brain were reasonably proportional to the peak SAR in the corresponding regions No clear difference in the correlation between the peak SAR and the maximum temperature increase was observed for infant and adult models Additionally, the effect of the material constants on the correlation was at most 10%
4 citations
TL;DR: In this article, the authors proposed a model for estimating the electromagnetic interference with the pacemaker as a receiving antenna, and applied the model to the qualitative evaluation of the EMI reduction produced by wearing the shielding material.
Abstract: In order to guard continuously patients with a cardiac pacemaker from radio waves emitted by the portable information terminal, an effective way is to shield the human body electromagnetically with a shielding material. There remain many unknown points regarding the effectiveness of wearing the shielding material. The authors have proposed a model for estimating the electromagnetic interference (EMI) with the pacemaker as a receiving antenna. This paper applies the model to the qualitative evaluation of the EMI reduction produced by wearing the shielding material. The result of the proposed evaluation method is compared to the result of the conventional evaluation method, which is based on the reduction of the electromagnetic field in the torso not containing a pacemaker. It is found that, although the conventional method does not reflect exactly the true EMI reduction for the pacemaker, it is useful as a preliminary evaluation of the EMI level for the pacemaker. The elliptic cylinder torso model, composed of three layers of skin, fat, and muscle, is considered, and the reductions of the EMI level by the conductive and the magnetic sheets for the pacemaker are evaluated by the proposed method. The following results are obtained. When the antenna is placed at a distance of 1 cm from the torso, the EMI reduction effect of the magnetic material is equivalent to placing the antenna at 7 cm, and that of the conductive sheet is equivalent to placing the antenna at more than 20 cm. The latter result indicates that, even if the antenna approaches within 1 cm of the torso, the equivalent distance satisfying essentially the guideline (22 cm) of the Japanese Pacemaker Association is realized, if the conductive sheet is worn on the torso. © 2002 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 86(1): 48–53, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.10023
4 citations
Journal Article•
TL;DR: A 1.5GHz exposure setup was developed which has a highly localized specific absorption rate (SAR) of 2W/kg in the mouse brain and a low whole-body averaged SAR of 0.27W/ kg, which confirmed the effectiveness of the magnetic sheet attachment to the mouse holder.
Abstract: In testing the possible biological effects of electromagnetic exposure from cellular telephones in small animals such as mice, it is essential to realize a highly localized head exposure as close as possible to that due to cellular telephones in humans. In this study, a 1.5GHz exposure setup was developed which has a highly localized specific absorption rate (SAR) of 2W/kg in the mouse brain and a low whole-body averaged SAR of 0.27W/kg. The low whole-body averaged SAR was realized by using a flexible magnetic sheet attachment on the mouse holder. Its validity has been carefully examined by both numerical simulation with an anatomically based mouse model and experimental simulation with a solid mouse phantom. Good agreement was obtained between the numerical and experimental results, which confirmed the effectiveness of the magnetic sheet attachment to the mouse holder. key words: bio-electromagnetic environment, cellular telephone, animal experiment, exposure setup, absorbing material
3 citations
16 May 2003
TL;DR: In this paper, the authors investigated the relationship between the frequencies of peak emissions radiated from a printed circuit board and the resonance resistances of the PCB impedance from measurement and finite-difference time-domain (FDTD) analysis.
Abstract: It is well-known that the frequencies of radiated peak emissions due to the ground bounce of a printed circuit board (PCB) are related to the resonance frequencies of the input impedance between the power and ground planes (PCB input impedance), while their correspondence relationship is unclear. In this paper, we investigated the quantitative relationship between the frequencies of peak emissions radiated from a PCB and the resonance resistances of the PCB impedance from measurement and finite-difference time-domain (FDTD) analysis. As a result, we found that the ratio of squared electric far-fields at the PCB resonance frequencies corresponds to the ratio of radiated resonance power. This finding leads to the conclusion that the radiated peak emission frequency can be predicted from PCB resonance resistances and the internal resistance of the PCB excitation source