Calculation of Whole-Body Sar From a 100 MHZ Dipole Antenna

Zhang, Ming; Alden, A.

doi:10.2528/pier11052005

Cited by 33 publications

(27 citation statements)

References 15 publications

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“…However, this model only can provide a rough estimate of the path loss, which limits it applicability because more accurate estimates of path loss are required for simulations using the digital body model [30][31][32][33][34][35][36][37].…”

Section: Methods and Analysismentioning

confidence: 99%

The Use of a Human Body Model to Determine the Variation of Path Losses in the Human Body Channel in Wireless Capsule Endoscopy

Basar¹,

Malek²,

Juni³

et al. 2013

PIER

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Abstract-Presently, wireless capsule endoscopy (WCE) is the sole technology for inspecting the human gastrointestinal (GI) tract for diseases painlessly and in a non-invasive way. For the further development of WCE, the main concern is the development of a highspeed telemetry system that is capable of transmitting high-resolution images at a higher frame rate, which is also a concern in the use of conventional endoscopy. A vital task for such a high-speed telemetry system is to be able to determine the path loss and how it varies in a radio channel in order to calculate the proper link budget. The hostile nature of the human body's channel and the complex anatomical structure of the GI tract cause remarkable variations in path loss at different frequencies of the system as well as at capsule locations that have high impacts on the calculation of the link budget. This paper presents the path loss and its variation in terms of system frequency and location of the capsule. Along with the guideline about the optimum system frequency for WCE, we present the difference between the maximum and minimum path loss at different anatomical regions, which is the most important information in the link-margin setup for highly efficient telemetry systems in next-generation capsules. In order to investigate the path loss in the body's channel, a heterogeneous human body model was used, which is more comparable to the human body than a homogenous model. The finite integration technique (FIT) in Computer Simulation Technology's (CST's) Microwave Studio was used in the simulation. The path loss was analyzed in the frequency range of 100 MHz to 2450 MHz. The path loss was found to be saliently lower at frequencies below 900 MHz. The smallest loss was found around the frequency of 450 MHz, where the variation of path loss throughout the GI tract was 29 dB, with a minimum of −9 dB and a maximum of −38 dB. However, at 900 MHz, this variation was observed to be 38 dB, with a minimum of −10 dB and a maximum of −48 dB. For most positions of the capsule, the path loss increased rapidly after 900 MHz, reaching its peak at frequencies in the range of 1800 MHz to 2100 MHz. During examination of the lower esophageal region, the maximum peak observed was −84 dB at a frequency of 1760 MHz. The path loss was comparatively higher during examination of anatomically-complex regions, such as the upper intestine and the lower esophagus as compared to the less complex stomach and upper esophagus areas.

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Section: Methods and Analysismentioning

confidence: 99%

The Use of a Human Body Model to Determine the Variation of Path Losses in the Human Body Channel in Wireless Capsule Endoscopy

Basar¹,

Malek²,

Juni³

et al. 2013

PIER

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“…If measurement provides the average P a and SAR, by computation, local SAR values can be determined -being able to visualize the distribution of P a or of SAR over the sample's volume is of significant interest [26,27]. Understanding the distribution of absorption could be essential in microdosimetric investigations of biochemical effects at the level of cells dimension and below.…”

Section: Dosimetric Validation Of the Tem Cellmentioning

confidence: 99%

Design and Validation of a Tem Cell Used for Radiofrequency Dosimetric Studies

Iftode¹,

Miclăuș²

2012

PIER

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Abstract-A Transverse Electromagnetic Mode (TEM) cell is an interesting option for studying the biological effects of radiofrequency radiation at reduced scale (in vitro studies).Controlled and well-characterized exposure conditions are essential for a conclusive investigation: the biological sample is exposed to a uniform incident electromagnetic wave and the dose of absorbed radiation is precisely determined and correlated with the effect. Unfortunately, experimental dosimetry is often unavailable or inapplicable, so that a precharacterized and validated experimental setup is most valuable. As such, the primary objective of the present work is to experimentally validate a computational model of a self-built TEM cell designed for bioelectromagnetic experiments in the 100 MHz-1 GHz frequency range. Validation is achieved by comparing the computed vs. measured values for three significant parameters: scattering parameters, incident electric field distribution, and absorbed power in a set of liquid samples. Successful validation and characterization is achieved by using CST Microwave Studio's finite integration technique (FIT), and respectively a network analyzer for the experimental setup. The secondary objective is a dosimetric study of four different liquid samples loaded in the cell. The absorption coefficient (AC) is used, assimilated to the specific absorption rate (SAR) of energy deposition in the entire sample volume. AC is shown to converge in experiment and simulation up to 800 MHz for all samples. AC doesn't depend directly on the samples' volume (despite greater volumes frequently showing higher absorption) but rather upon the internal field distribution, which in turn mostly depends on the frequency and on the dimensions of the liquid samples.

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“…Many studies have evaluated the SAR in human body models [5][6][7][8][9][10]. Recently, compact antennas with a low SAR have become essential in the design of handsets.…”

Section: Introductionmentioning

confidence: 99%

Analysis of Materials Effects on Radio Frequency Electromagnetic Fields in Human Head

Islam¹,

Abidin

Faruque

et al. 2012

PIER

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Abstract-In this paper, we propose to study the variability of specific absorption rate (SAR) of a human head due to different materials in the vicinity of the handset. We include the effects of the human hand, handset chassis and additional conductive material particularly handring jewelry. A finite-difference time-Domain (FDTD) method was used to analyze different positions of the conductive ring materials within the hand model. Furthermore, the impact of this material on the performance of an antenna was considered in this study. We found that including a hand model leads to a significant reduction in SAR. The hand influences not only SAR distribution but also antenna performance. Moreover, adding conductive materials to the hand results in increases in the local SAR values of the head model. The results suggest that the hand model is important in SAR evaluation and that having an additional conductive material on the hand may vary the amount of electromagnetic (EM) energy absorption depending on the position of the material.

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Calculation of Whole-Body Sar From a 100 MHZ Dipole Antenna

Cited by 33 publications

References 15 publications

The Use of a Human Body Model to Determine the Variation of Path Losses in the Human Body Channel in Wireless Capsule Endoscopy

The Use of a Human Body Model to Determine the Variation of Path Losses in the Human Body Channel in Wireless Capsule Endoscopy

Design and Validation of a Tem Cell Used for Radiofrequency Dosimetric Studies

Analysis of Materials Effects on Radio Frequency Electromagnetic Fields in Human Head

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