EVALUATION OF SPECIFIC ABSORPTION RATE IN THE FAR-FIELD, NEAR-TO-FAR FIELD AND NEAR-FIELD REGIONS FOR INTEGRATIVE RADIOFREQUENCY EXPOSURE ASSESSMENT

2020 ◽  
Vol 190 (4) ◽  
pp. 459-472 ◽  
Author(s):  
Ilaria Liorni ◽  
Myles Capstick ◽  
Luuk van Wel ◽  
Joe Wiart ◽  
Wout Joseph ◽  
...  
Keyword(s):  
Large Scale ◽  
Absorption Rate ◽  
Specific Absorption Rate ◽  
Numerical Study ◽  
Whole Body ◽  
Single Frequency ◽  
Far Field ◽  
Specific Absorption ◽  
Rf Systems ◽  
Body Tissues

Abstract The specific absorption rate (SAR) induced by wireless radiofrequency (RF) systems depends on different parameters. Previously, SAR was mainly assessed under conditions of a single frequency and technology and for a limited number of localized RF sources. The current and emerging mobile systems involve a wider range of usage scenarios and are frequently used simultaneously, leading to combined exposures for which almost no exposure evaluation exists. The aim and novelty of this study is to close this gap of knowledge by developing new methods to rapidly evaluate the SAR induced by RF systems in such scenarios at frequencies from 50 MHz to 5.5 GHz. To this aim, analytical methods for SAR estimation in several usage scenarios were derived through a large-scale numerical study. These include subject-specific characteristics, properties of the RF systems and provide an estimation of the SAR in the whole body, tissues and organs, and different brain regions.

scholarly journals The specific absorption rate in different brain regions of rats exposed to electromagnetic plane waves

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Hao-Yu Wang ◽  
Chun-Fang Li ◽  
Chao Yu ◽  
Ji Dong ◽  
Yong Zou ◽  
...  
Keyword(s):  
Brain Region ◽  
Absorption Rate ◽  
Specific Absorption Rate ◽  
Brain Regions ◽  
Dose Effect ◽  
Whole Body ◽  
Polarization Direction ◽  
Whole Brain ◽  
Specific Absorption ◽  
Effect Relationship

Abstract Accurate dosimetry of a specific brain region in rats exposed to an electromagnetic field (EMF) is essential for studies focusing on dose-effect relationship of the region. However, only dosimetry of whole brain or whole body were evaluated in most of previous studies. In this study, a numerical voxel rat model with 10 segmented brain regions was constructed. Then, the effects of frequency, incidence direction, and E-polarization direction of plane wave EMF on brain region averaged specific absorption rate (BRSAR) of rats were investigated. At last, the reliability of using whole-body averaged SAR (WBDSAR) and whole-brain averaged SAR (WBRSAR) as estimations of BRSAR were also evaluated. Our results demonstrated that the BRSAR depended on the frequency, incidence direction, and E-polarization direction of the EMF. Besides, the largest deviation could be up to 13.1 dB between BRSAR and WBDSAR and 9.59 dB between BRSAR and WBRSAR. The results suggested that to establish an accurate dose-effect relationship, the variance of the BRSAR induced by alteration of frequency, incidence direction, and E-polarization direction of EMF should be avoided or carefully evaluated. Furthermore, the use of WBDSAR and WBRSAR as estimations of BRSAR should be restricted to certain conditions such that the deviations are not too large.

scholarly journals Improved Handset Antenna Performance via an Electrically Extended Ground Plane

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Shirook M. Ali ◽  
Huanhuan Gu ◽  
Kelce Wilson ◽  
James Warden
Keyword(s):  
Absorption Rate ◽  
Specific Absorption Rate ◽  
Near Field ◽  
Ground Plane ◽  
Practical Approach ◽  
Far Field ◽  
Specific Absorption ◽  
Antenna Performance ◽  
Field Patterns ◽  
Surface Metal

A novel and practical approach is presented providing improved antenna performance without enlarging the antenna or the ground plane. The approach electrically extends the ground plane using wire(s) that behave as surface metal extensions of the ground plane. The wire extensions can be accommodated within typical handset housing or as part of the stylish metal used on the handset’s exterior perimeter; hence don’t require enlargement of the device. Consequently, this approach avoids the costs and limitations traditionally associated with physically lengthening of a ground plane. Eight variations are presented and compared with baseline antenna performance. Both far-field patterns and near-field electromagnetic scans demonstrate that the proposed approach controls the electrical length of the ground plane and hence its chassis wavemodes, without negatively impacting the characteristics of the antenna. Improvements in performance of up to 56% in bandwidth at 900 MHz and up to 12% in efficiency with a reduction of up to 12% in the specific absorption rate (SAR) are achieved. An 8% increase in efficiency with a 1.3% improvement in bandwidth and a 20% reduction in SAR is achieved at 1880 MHz. Thus, improvements in bandwidth are achieved without compromising efficiency. Further, improvements at lower frequencies do not compromise performance at higher frequencies.

Variation of whole body averaged phantom specific absorption rate (SAR) in seven different 1.5 T MR systems

2008 ◽  
Author(s):  
Wolfgang Kainz ◽  
Florian Fidler ◽  
Jean Bobgan ◽  
Gregor Schaefers ◽  
Roger Luechinger ◽  
...  
Keyword(s):  
Absorption Rate ◽  
Specific Absorption Rate ◽  
Whole Body ◽  
Specific Absorption
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