Dependence of specific absorption rate and its distribution inside a homogeneous fruit model on frequency, angle of incidence, and wave polarization

Frequenz ◽  
2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Ardhendu Kundu ◽  
Bhaskar Gupta ◽  
Amirul I. Mallick
Keyword(s):  
Dielectric Properties ◽  
Power Density ◽  
Absorption Rate ◽  
Specific Absorption Rate ◽  
Electromagnetic Energy ◽  
Far Field ◽  
Angle Of Incidence ◽  
Wave Polarization ◽  
Regulatory Guidelines ◽  
Sar Data

Abstract Electromagnetic regulatory guidelines prescribed by the international and national organizations are in effect worldwide to protect humans from immediate health effects. For restricting human exposure to electromagnetic radiation in near field, a quantitative term ‘specific absorption rate (SAR) limit’ has been coined and well established in literature. In addition, reference power density limit has also been prescribed in far field for human safety. At the same time, plants and fruits also absorb reasonable amount of electromagnetic energy due to high permittivity and electrical conductivity. Unfortunately, there is not much concern regarding electromagnetic energy absorption in plants and fruits, and no prescribed SAR limit in spite of recent reports in literature. Unlike humans, plants and fruits are of asymmetric shapes and sizes; therefore even at a particular frequency and fixed reference power density, electromagnetic energy absorption rate i.e., SAR in plants and fruits is expected to differ depending upon angle of incidence and wave polarization. To address these issues in detail, a typical bunch of three single layered water apples has been prototyped and exposed to plane wave irradiation at five different frequency bands as per the existing Indian electromagnetic regulatory guidelines. Broadband dielectric properties of water apples have been measured using open ended coaxial probe technique; thereafter, measured dielectric properties have been fed into the designed model. At a particular frequency, reasonable variations in magnitude and position of maximum local point (MLP) SAR, 1 g averaged SAR, and 10 g averaged SAR data have been noted for six different combinations of angle of incidence and wave polarization. This whole course of action is repeated over five different frequency bands. Moreover, variations in observed SAR data are also compared with previously reported variations in SAR data for a multilayer fruit structure. Observations indicate different order of changes in SAR for different fruit structures due to similar combinations of frequency, power density, angle of incidence, and wave polarization. Hence, direct definition of SAR limits for plant and fruit structures should be adopted even in far field in conjunction with reference power density.

scholarly journals Finite Element Analysis of the Microwave Ablation Method for Enhanced Lung Cancer Treatment

Cancers ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 3500
Author(s):  
Marija Radmilović-Radjenović ◽  
Martin Sabo ◽  
Marta Prnova ◽  
Lukaš Šoltes ◽  
Branislav Radjenović
Keyword(s):  
Dielectric Properties ◽  
Cancer Cells ◽  
Microwave Ablation ◽  
Absorption Rate ◽  
Specific Absorption Rate ◽  
Surrounding Tissue ◽  
Physical Parameters ◽  
Medical Procedure ◽  
Ablation Zone ◽  
Specific Absorption

Knowledge of the frequency dependence of the dielectric properties of the lung tissues and temperature profiles are essential characteristics associated with the effective performance of microwave ablation. In microwave ablation, the electromagnetic wave propagates into the biological tissue, resulting in energy absorption and providing the destruction of cancer cells without damaging the healthy tissue. As a consequence of the respiratory movement of the lungs, however, the accurate prediction of the microwave ablation zone has become an exceptionally demanding task. For that purpose, numerical modeling remains a primordial tool for carrying out a parametric study, evaluating the importance of the inherent phenomena, and leading to better optimization of the medical procedure. This paper reports on simulation studies on the effect of the breathing process on power dissipation, temperature distribution, the fraction of damage, and the specific absorption rate during microwave ablation. The simulation results obtained from the relative permittivity and conductivity for inflated and deflated lungs are compared with those obtained regardless of respiration. It is shown that differences in the dielectric properties of inflated and deflated lungs significantly affect the time evolution of the temperature and its maximum value, the time, the fraction of damage, and the specific absorption rate. The fraction of damage determined from the degree of tissue injury reveals that the microwave ablation zone is significantly larger under dynamic physical parameters. At the end of expiration, the ablation lesion area is more concentrated around the tip and slot of the antenna, and the backward heating effect is smaller. The diffuse increase in temperature should reach a certain level to destroy cancer cells without damaging the surrounding tissue. The obtained results can be used as a guideline for determining the optimal conditions to improve the overall success of microwave ablation.

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.

Biological effect of SAR on the human head due to variation of dielectric properties at 1800 and 2450 MHz with different antenna substrate materials

2015 ◽  
Vol 22 (4) ◽  
Author(s):  
Mohammad Rashed Iqbal Faruque ◽  
Mohammad Tariqul Islam ◽  
Mohammad Habib Ullah
Keyword(s):  
Dielectric Properties ◽  
Time Domain ◽  
Finite Difference Time Domain ◽  
Biological Effect ◽  
Absorption Rate ◽  
Specific Absorption Rate ◽  
Fdtd Method ◽  
Human Head ◽  
Substrate Material ◽  
Difference Time

AbstractThe aim of this study was to consider a possible discrepancy in electromagnetic (EM) absorption in the human head. The finite-difference time-domain (FDTD) method with the lossy Drude model was adopted in this study. Here, the permittivity and conductivity of all head tissues were increased from 10% to 20% except when not using the same exposure conditions. Recognizable mobile phone frequencies of 1800 and 2450 MHz were studied in this simulation. The increase of up to 20% in conductivity and permittivity and varied substrate material always caused an EM absorption variation of 32.59% for specific absorption rate (SAR) 1 g and 35.25% for SAR 10 g at 1800 MHz, and variation of 20.37% for SAR 1 g and 17.99% for SAR 10 g at 2450 MHz, respectively.

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 Analysis and Evaluation of Specific Absorption Rate of GSM Signal in Port Harcourt, Nigeria

2019 ◽  
pp. 1-10
Author(s):  
Promise Elechi ◽  
Sunny Orike ◽  
Promise Agugharam
Keyword(s):  
Electric Field ◽  
Radio Frequency ◽  
Human Health ◽  
Power Density ◽  
Human Body ◽  
Absorption Rate ◽  
Specific Absorption Rate ◽  
Specific Absorption ◽  
Radio Frequency Radiation ◽  
Frequency Radiation

There is a growing concern in the world that residents close to GSM base station facilities are exposed to electromagnetic radiation which causes different health illness like cancer, leukemia, memory lost, dizziness, fatigue, etc. This study puts to rest the position on the effect of radiofrequency (RF) radiation from GSM masts on human health. In this research work, the evaluation and assessment of radio frequency radiation in five selected mobile base stations facilities in Obio/Akpor Local Government of Rivers State, Nigeria were carried out using an EMF meter for measurement of Electric field. The measurements of the radio frequency radiation with the EMF meter was conducted from 0 – 300m away from the selected base transceivers stations facilities of the selected telecommunication operators (MTN, Globacom and Airtel) in Nigeria. The data obtained from the research were analyzed using Specific Absorption Rate formula to establish whether with time exposure to RF radiation will have negative impact on human health. The normal specific absorption rate (SAR) and the Power Density for the general public whole body was assessed from the measured electric field strength and the results were compared with that of International Commission on Non Ionization Radiation Protection (ICNIRP).The results showed that the average amount of SAR for the selected five base transceiver station (BTS) facilities were within the range of 0.0037 W/kg – 0.0084 W/kg and the power density 1.5183 W/m2 – 9.5083 W/m2. These values are lower than the recommended limit by ICNIRP which is 0.08w/kg for the human body. This study has shown that there is inconsequential effect on human health because the non-ionizing electromagnetic energy has no sufficient energy to affect any part of human body for the residents living close to the selected BTS facilities of the various telecommunication providers.

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