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The specific absorption rates (SAR) determined computationally in the specific anthropomorphic mannequin (SAM) and anatomically correct models of the human head when exposed to a mobile phone model are compared as part of a study organized by IEEE Standards Coordinating Committee 34, SubCommittee 2, and Working Group 2, and carried out by an international task force comprising 14 government, academic, and industrial research institutions. The detailed study protocol defined the computational head and mobile phone models. The participants used different finite-difference time-domain software and independently positioned the mobile phone and head models in accordance with the protocol. The results show that when the pinna SAR is calculated separately from the head SAR, SAM produced a higher SAR in the head than the anatomically correct head models. Also the larger (adult) head produced a statistically significant higher peak SAR for both the 1- and 10-g averages than did the smaller (child) head for all conditions of frequency and position. Index Terms--FDTD methods, IEEE standards, phantom, simulation, software standards, specific absorption rate (SAR), specific anthropomorphic mannequin (SAM).

A hybrid approach combining the method of moment (MoM) and the finite-difference time-domain (FDTD) method is applied to a problem of evaluating specific absorption rates (SARs) in a small rat inside a reverberation chamber (RC). The hybrid method is an alternative technique used to overcome the problem of poor convergence for a solution of the FDTD method in analyzing the RC. First, the RC with a dipole or a helical antenna is designed numerically to function properly at 2 GHz. Then, the MoM/FDTD method is used to calculate the whole-body average SAR (WBA-SAR) for a small animal inside an open cavity. The results are compared with those obtained with the FDTD method in order to verify accuracy. The SAR distributions when stirrers are rotating are also determined. Finally, it is numerically found that the ratio of the WBA-SAR of the 118 g rat to the mean squared electric field is 0.149 (mW/kg)/(V/m)^2 and an input antenna power of 2.2 W is required to produce a WBA-SAR of 4 W/kg for our designed chamber. [ABSTRACT FROM AUTHOR]

In view of actual electromagnetic environment of multiple-frequency exposure, we have developed a whole-body exposure system for a multigeneration bio-effect test with rats at frequencies between 800 MHz and 5.2 GHz. We first experimentally evaluated the system performances such as antenna performance, electric field distribution, and specific absorption rate (SAR) in the exposure system. Then, after an experimental validation of the finite-difference time-domain modeling of the exposure system, we employed it to make a statistical SAR analysis for anatomical rat models. We first took documentary photographs of rat activity inside the exposure system every 5 min in real time. Then, by identifying the rat positions in each photograph, we derived the frequency of rats staying in various positions in the exposure system. Using the stay frequency as a weighting factor, we derived the whole-body average SAR statistical characteristics for the multiple-frequency exposure system during the entire multigeneration experimental period. The developed system and demonstrated approach provide a high-quality means for biological effect test of radio frequency exposure in wide frequency bands. [ABSTRACT FROM AUTHOR]

The frequency at the peak of electromagnetic radiation from a PCB (Printed Circuit Board) as a result of ground bounce is considered predictable from the frequency characteristics of the input impedance between the power supply and ground layer (below called the PCB impedance). However, the relationship is largely unknown. In this paper, the electromagnetic radiation of the PCB and the frequency spectrum of the PCB impedance are analyzed by the FDTD (Finite-Difference Time-Domain) method and their relational mechanism is studied by comparison with the measured values. It is found that the peak of the electromagnetic radiation appears at the frequency where the PCB is a minimum if the PCB is excited by a voltage source with an internal resistance sufficiently smaller than the PCB impedance, and that this peak is shifted toward the frequency at which the PCB impedance becomes a maximum if the internal resistance is increased. The radiation power ratio derived from the resistive components (called the resonant resistances) at two frequencies where the PCB impedance is maximum and minimum (resonant frequencies) mostly agrees with the ratio of the squares of the radiated electric field. Hence, the radiation peak frequencies of the PCB are determined both by the internal resistance of the excitation source and the resonant resistance of the PCB impedance. © 2004 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 87(11): 30–38, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.10209 [ABSTRACT FROM AUTHOR]

Investigates the human-body effect on the peak specific absorption rate (SAR) in the human head for portable telephones. Use of parallel finite-difference time-domain computation system on Linux-based personal computers; Finding of a difference in the averaged spatial peak SAR and a difference in the SAR in the brain and eyes compared to the isolated head model; Slight decrease in the SAR due to the body effect.

We propose a local Specific Absorption Rate (SAR) estimation system using solid phantom and fixed E-field probe for application to portable wireless devices such as cell phones. This system is constructed from a solid phantom molded from a lossy dielectric and an electric field (E-field) probe inserted into the phantom. The advantage of this system is the ability to easily measure in a relatively short time the local SAR with measurement deviations of about ±30% compared to the measurements made by the conventional technique using a liquid phantom. First, we perform numerical analysis using the finite-difference time-domain (FDTD) method in the basic parameter design to clearly show the effects of the size of the insertion hole for the E-field probe in the solid phantom and the complex dielectric permittivity on the antenna input impedance and local SAR. Next, we develop a local SAR estimation system using solid phantom and fixed E-field probe, and measure and evaluate the antenna input impedance and local SAR of two solid phantoms having different complex dielectric permittivities. We confirmed that their properties tend to nearly agree with the calculated results. Finally, we measure the local SARs of 32 portable phones using this system. We confirmed that compared to the measurements by the E-field probe scanning method, the measurements of about 77% of the phones have deviations within 30%, and the target measurement accuracy during development could almost be achieved. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 86(9): 46–56, 2003; Published online in Wiley InterScience (www.interscience.wiley. com). DOI 10.1002/ecja.10082 [ABSTRACT FROM AUTHOR]

In a discharge between charged metal spheres, the effect of the metal spheres on the generated electromagnetic field has not been clearly indicated. One of the authors (Fujiwara) has proposed the following computation method (called the image dipole method) for a spark discharge between metal spheres. The surface of the metal sphere is replaced by an infinite number of image charge pairs, which are arranged so that the surface is kept at the same potential. Then, the generated electromagnetic field is calculated analytically by superposition of the dipole fields caused by the spark current derived from the Rompe-Weizel spark-resistance law. It has been shown by the analysis that the metal sphere increases the field level. Then, the electromagnetic field generated by the spark discharge between metal spheres is calculated numerically by the finite-difference time-domain (FDTD) method, with the spark current as an excitation source for the metal sphere. The validity of the approach has been shown through comparison to the analytic solution by the image dipole method for the magnetic field waveform. However, the above computation method has the problem that the static electric field before the onset of the discharge cannot be calculated, which makes it difficult to understand fully the ESD field produced by the charged metal bodies. In this paper, the generated electromagnetic field is calculated by the FDTD method (voltage source method), with the spark voltage derived from the spark-resistor law as an excitation source. The result is compared to the results of calculations by the image dipole method and the current source method. It is shown that the waveform of the electrostatic field cannot be calculated by the current source method, but the voltage source method can calculate the field as in the case of the image dipole method. It is also seen that the magnetic field waveforms obtained by any calculation almost completely agree. The magnetic field waveform generated in the discharge experiment between metal spheres is observed by using a shielded magnetic field probe and a wideband oscilloscope (bandwidth 1.5 GHz), and is shown to agree almost completely with the results of calculations by the voltage source method and the image dipole method. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 86(7): 54–63, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.1169 [ABSTRACT FROM AUTHOR]

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 [ABSTRACT FROM AUTHOR]

It is not known what kind of influence metallic bodies exert on the transient electromagnetic field generated by a spark discharge between charged metals. In this article, the electromagnetic fields generated by spark discharges between metallic spheres are numerically analyzed by the finite-difference time-domain (FDTD) method. It is found that the presence of the metallic bodies can increase the field level depending on their size. Next, the condition for maintaining the metallic spherical surfaces at a constant potential is created by an image charge pair. The generated magnetic field is derived by superposing the electromagnetic fields by the dipole models with the same charge pair. The numerical results almost entirely agree with those obtained by the FDTD method. The validity of the FDTD findings is confirmed. © 2000 Scripta Technica, Electron Comm Jpn Pt 2, 83(2): 44–51, 2000 [ABSTRACT FROM AUTHOR]