The purpose of this paper is to determine the specific absorption rate (SAR) in the human head in 10 g of mass tissues due to mobile phone exposure with walls nearby. The mobile phone was modeled as a Ȝ/4 monopole antenna placed at a distance of 1 mm from the human head and the SAR values were determined using CST software for two GSM frequencies, 900 and 1800 MHz taking into consideration different placements of the walls in the head vicinity and antenna positions too. As a particular application SAR was determined when the human head is situated inside a metallic cage whose dimensions are comparable with an elevator cabin.
Keywords-numerical methods, , CST software, realistic human model, specific absorption rate (SAR)I.
This paper presents an analysis of the levels of electromagnetic fields caused by cellular base stations or mobile phones, measured in some residential areas. A statistical processing of the data has also been done in order to estimate both the short-term and the long-term variability of the fields caused by cellular base stations in some apartments and on the terraces of the apartment buildings at tens or hundreds of meters distance from the antenna systems. In some places, comparative measurements of the electromagnetic fields were performed, using two different antennas, namely the horn antenna and, respectively, the log periodic antenna, with the aim to determine the electromagnetic fields caused by mobile communication systems. This will allow to estimate the electromagnetic interference on electronic devices or on human beings, namely to calculate the relative exposure index or the specific absorption rate-SAR.
With a view to make a long term survey of the magnetic fields generated by the power line sources, appliances or, generally, by the low frequency magnetic field sources, a tri-axis magnetic field meter was proposed. Referring to the magnetic field sensor, both the characteristic proportional of the field strength and proportional to the time derivate of the field strength were considered. Thus, two active magnetic field meters working in 40 Hz -200 kHz frequency range were designed. In this mode it is possible to make the time domain or/and the frequency domain magnetic field measurement in a frequency range considered unitary from biological and health effects point of view. By using three orthogonal magnetic field sensors, and an electronic processing system it is possible to obtain the waveforms of the three orthogonal components, H 1 , H 2 , H 3 of the magnetic field vector. Based on the root mean square (r.m.s.) values of these orthogonal field components, the r.m.s. value of the resultant magnetic field vector was determined. Also, it is possible to determine the peak values of the magnetic fields. The recording, processing and storage of the data were made by software, using a National Instruments acquisition system connected at a portable computer. This proposed measurement system is autonomous, portable and it is able to make automate measurements of the fields with storage of data, being adequate to long term survey of magnetic fields. Using these presented measurement systems, comparative measurements and a survey of background magnetic fields in residential areas and in some special places, namely near some appliances, near power line systems and in hospitals electrotherapy rooms, were made.
The aim of this research is to perform a quick and mainly qualitative evaluation of the environmental radio frequency electromagnetic fields in some apartments and public places that are representative for most of the exposure situations that can occur in urban areas. This study can be a starting base for developing a risk of exposure evaluation questionnaire. Two types of exposure situations are considered in measurements: places situated in the vicinity (but in far field zone) of the main sources and places situated remotely from main sources. Also an exposure evaluation is performed for each case, taking into account the pollution from all sources together. There were found field levels of about tens to hundreds of mV/m and relative exposure of about 5x10-5 to 8x10-5 in the "source vicinity" cases and about few to tens of mV/m and relative exposure of about 3x10-6 to 1.4x10-5 in the "remotely by source" cases.
Keywords-Radio frequency electromagnetic fields measurements, electromagnetic pollution, exposure to electromagnetic fields I.
In the present paper, the field quantities as the induced current (I z), the current density (J z), and the induced electric field (E z) for the case of humans exposed to an external electromagnetic field were determined via different analytical methods. To study these induced field quantities, the spherical model of the human head was used for two frequencies domains-low and high frequencies. The values of the current density determined by analytical methods are compared with those obtained by numerical simulation using adequate electromagnetic field analysis software such as the CST Studio Suite and COMSOL Multiphysics.
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