Showing papers by "Jianqing Wang published in 2000"

A model for predicting electromagnetic interference of implanted cardiac pacemakers by mobile telephones

Abstract: A prediction of the electromagnetic interference (EMI) of pacemakers due to mobile phones is significant in improving the immunity of pacemakers. The Pacemaker Committee of Japan recently conducted immunity tests of pacemakers for mobile phones, and consequently concluded that the connector between the pacemaker housing and the lead wire of the electrode plays a major role for the EMI due to mobile phones. Based on this finding, a computer model for predicting the EMI level has been presented, in which the internal impedance seen from the connector was considered as a load, and the metal portions consisting of the pacemaker housing and the lead wire of the electrode were considered as two elements of a receiving antenna. Interference voltages induced through the connector were analyzed by using the finite-difference time-domain method in conjunction with a torso and mobile phone model. The modeling was validated by comparison with previously reported experimental results.

FDTD Analysis of Dosimetry in Human Head Model for a Helical Antenna Portable Telephone

Abstract: This paper presents a dosimetric analysis in an anatomically realistic human head model for a helical antenna portable telephone by using the finite-difference time-domain (FDTD) method. The head model, developed from magnetic resonance imaging (MRI) data of a Japanese adult head, consists of 530 thousand voxels, of 2 mm dimensions, segmented into 15 tissue types. The helical antenna was modeled as a stack of dipoles and loops with an adequate relative weight, whose validity was confirmed by comparing the calculated near magnetic fields with published measured data. SARs are given both for the spatial peak value in the whole head and the averages in various major organs. key words: electromagnetic dosimetry, helical antenna,

Modeling of electromagnetic interference to an implanted cardiac pacemaker due to mobile phones

Abstract: Modeling the electromagnetic interference (EMI) of pacemakers due to mobile phones is essential to evaluate the EMI level and improve the immunity of pacemakers. The Pacemaker Committee of Japan conducted immunity tests of pacemakers for mobile phones, and consequently concluded that the connector between the pacemaker housing and the lead wire of the electrode plays a major role in the EMI due to mobile phones. Based on this finding, a model for the EMI mechanism was presented, in which the internal impedance looked from the connector and the metal portion consisting of the pacemaker housing and the lead wire of the electrode were considered as a load and two halves of a receiving antenna, respectively. The EMI level induced through the connector was analyzed by using the finite-difference time-domain (FDTD) method in conjunction with a torso and mobile phone models. The modeling given here was validated by comparison with the previously reported experimental results.

Dosimetry Evaluation and Tissue Structure Dependence of Localized Peak SAR inside Head Model for 1.5GHz Microwave Far-field Exposure

Abstract: Dosimetry Evaluation and Tissue Structure Dependence of Localized Peak SAR inside Head Model for 1.5GHz Microwave Far-field Exposure Takuji USHIMOTO, Non-member, Jianqing WANG, Non-member, Osamu FUJIWARA, Member (Faculty of Engineering, Nagoya Institute of Technology, Nagoya-shi, 466-8555 Japan) We investigated the relationship between the constituent tissue number and the localized peak SARs (specific absorption rate) inside an our newly developed MRI (Magnetic Resonance Imaging) based head model for far-field exposure with respect to all irradiating directions of the microwaves being employed for portable telephones. The FDTD (Finite-Difference Time-Domain) method was used to compute the SARs inside the MRI based head models consisting of various tissues up to fifteen kinds for 1.5 GHz microwave far-field exposure of 1 mW/cm2 specified in an uncontrolled environment. As a result, we found that in the head model having less than three kinds of tissue, the localized peak SAR reaches maximum for side irradiation, decreasing with increasing the tissue kind, while in the head model with more than four kinds of tissue, the localized peak SAR reaches maximum for rear irradiation, whose value increases with the tissue kind and reaches saturation point for over five tissues including skin, fat, muscle, bone, and brain. The latter finding suggests that the head model having the above five tissues at most can be used enough for dosimetry evaluation with high accuracy.