Comparisons of Computed Mobile Phone Induced SAR in the SAM Phantom to That in Anatomically Correct Models of the Human Head (original) (raw)
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PIERS Online, 2006
Since the 1990's, use of mobile phones has augmented worldwide generating a public concern as to whether frequent utilization of such devices is unsafe. This provoked EMF researchers to find suitable techniques of assessing radiation blueprint and exposure hazards if any. Most research groups focused on two techniques: experimental measurements and finite-difference time-domain (FDTD) computations. Computation of the specific absorption rate (SAR) generated by cellular phones inside two models of the human head is presented in this paper. Two models of mobile phones were considered working at 900 and 1800 MHz bands according to the Global System for Mobile Communication. Radiated energy distributions and averaged SAR values in 1 g and 10 g of tissue were computed inside the models of head using FDTD. Computations were compared with a realistic head model constructed with the MRI scans. The distribution of the local SAR in the head was similar to that of the simplified head models. The maximum local SAR calculated was 53.43 W/kg and the maximum SAR(10 g) was 2.96 W/kg, both for 1 W output power from the antenna. The results indicated the area of the maximum local SAR was situated in outer layer of skull, where muscle and skin were. The important parameters in absorbed energy in the head were the type of antenna, current distribution and the distance between head and antenna. The head models used for simulation proved as insignificant parameter in the calculations.
IEEE Transactions on Electromagnetic Compatibility, 1996
The purpose of this paper is to calculate the specific absorption rate (SAR) distribution in a human head exposed to the electromagnetic field emitted from a handheld cellular phone operating in the 900 MHz range in a partially closed environment. The environment could be, for example, the interior of a car, a condition of exposure which is largely diffused nowadays. The presence of reflecting surfaces near the phone modifies the current distribution on, and the emitting properties of, the phone antenna. Therefore, the distribution of the absorbed power inside the head is different from that absorbed in the free space exposure condition. The finite-difference time-domain (FDTD) method has been used to evaluate the SAR in a realistic anatomically based model of the human head for different antenna-handset configurations and for different antenna-head distances. The environmental effects have been simulated through partially or totally reflecting walls located in various positions with reference to the phone. It is found that the presence of a horizontal reflecting wall over the head decreases the SAR values in the part of the head directly exposed to the phone antenna, while it increases the SAR values in the part not directly exposed. On the contrary, the presence of a vertical wall, located in proximity of the phone and parallel to it, raises the SAR values everywhere into the head.
The Journal of the University of Duhok, 2020
Exposure human tissue to electromagnetic radiation (EM) from radio wireless frequencies causes many negative health effects. The assessment of the absorbed EM by human tissue depends on the Specific Absorption Rate (SAR) factor. In this paper, a square patch antenna (SPA) is designed to be a source of EM radiation, and optimized to operate at several applicable frequencies, such as GSM 1800, IEEE 802.11 WLAN standard 2.4 GHz and 5.3 GHz bands, and 3.2 GHz WiMAX band. The radiated EM by the SPA antenna is evaluated in a 3D human head model or Specific Anthropomorphic Model (SAM), which consists of two layers, the outer shell (1.5 mm thickness) and filled with tissue simulating liquid (TSL). The investigation involved four aspects, first the distance between the SAM and the EM source has been moved between 0 mm to 50 mm, second for the specific distances (0 mm, 15 mm, 30 mm, and 45 mm) the frequency of EM source has been changed among 1.8 GHz, 2.4 GHz, 3.2 GHz, and 5.3 GHz. Third, the tilt angle (θ) between the SAM and the antenna has been shifted from 0 0 to 90 0. Finally, the antenna encasement (2 mm thickness plastic material) was removed and the procedure in the first step is repeated to investigate the effect of encasement on the SAR reducing. The results reveal that there is an inversely proportional relation between SAR and distance, SAR and tilt angle. Besides, the antenna encasement has a large impact on attenuating SAR value, while the SAR is directly proportional to frequency. All SAR evaluations were performed by CST-2014 Microwave studio simulator which is built on the Finite-Difference-Time-Domain (FDTD) principle. All calculations are achieved over 1 g and 10 g of mass tissue averaging and according to IEEE/IEC 62704-1 standards.
2014 XXXIth URSI General Assembly and Scientific Symposium (URSI GASS), 2014
This paper presents finite-difference-time-domain (FDTD) calculations of the specific absorption rate (SAR) in realistic head models from exposure to a generic handset working as 1750 Mhz. The head models with different sizes were obtained from the same whole-body model. The purpose of this work is to study whether there is a variation of SAR absorption in the same brain, but the sizes of head models are different. The obtained peak SARs in each of the tissues were averaged over 10 grams of tissue in the shape of cube. It was found that the SAR absorption in human brain is dependent on the size of the head model. The induced SAR in brain tissues in smaller head model is larger than that in larger head model. It suggested that the mobile phone dosimetric analysis in most of the previous literatures which only considered head model in the simulation may overestimate the brain exposure compared to the practical situation that the whole-body exposed to the fields radiated by the mobile phone.
SAR assessment in a human head model exposed to radiation from mobile phone using FEM
IEEE International Symposium on Electromagnetic Compatibility
It is important to be able to quantib both the absorption of electromagnetic energp in the human body and the resulting thermal effect. In this study, the specific absorption rate (SAR) of electromagnetic radiation /+om mobile phones on the human head was investigated As if is not possible to perform the experiments on human in vivo, the human head and the antenna radiated in 900 MHz were simulated. In this study, the spherical model as single layer and three layers was simulated by using Agilent High Frequency Sfructure Simulator, which employs the finite element method (FEW, and the EMpower absorption rate of tissue was calculated by a C++ program. The results were compared with the results of the sfudies in the literalure and a good agreement was obtained. To evaluate the efticiency of the method, a rat head was simulated and the results were compared with the experimental results obtained @om the in vivo experiments conducted on the rats.
IET Seminar Digests, 2007
This paper presents the effects of facial metallic pins on the Specific Absorption Rate (SAR) in the head, when radiated by a microwave source placed in front of the face. A Specific Anthropomorphic Mannequin (SAM) is adapted for use with a DASY4 and a digitised SAM head is modelled using inhouse Finite-Difference Time-Domain (FDTD) code, enabling comparisons between measurements and simulations. A continuous wave (CW) half-wave dipole is placed in front of the face, representing a communications enabled personal data assistant mobile communications equipment (PDAMCE). Parametric studies have shown that metallic pins that are roughly half a wavelength long placed along the eyebrow, increase the 1g and 10g SARs at 900MHz by around five fold. A greater than five fold increase is seen at 1800MHz. Measurements show very good agreement with simulations.
IEEE Transactions on Antennas and Propagation, 1998
The use of primates for examining the effects of electromagnetic radiation on behavioural patterns is well established. Rats have also been used for this purpose. However, the monkey is of greater interest as its physiological make-up is somewhat closer to that of the human. Since the behavioural effects are likely to occur at lower field strengths for resonant absorption conditions for the head and neck, the need for determination of resonance frequencies for this region is obvious. Numerical techniques are ideal for the prediction of coupling to each of the organs, and accurate anatomically based models can be used to pinpoint the conditions for maximum absorption in the head in order to focus the experiments. In this paper we use two models, one of a human male and the other of a rhesus monkey, and find the mass-averaged power absorption spectra for both. The frequencies at which highest absorption (i.e. resonance) occurs in both the whole body and the head and neck region are determined. The results from these two models are compared for both E-polarization and k-polarization, and are shown to obey basic electromagnetic scaling principles.
Bioelectromagnetics, 2005
A new human head phantom has been proposed by CENELEC/IEEE, based on a large scale anthropometric survey. This phantom is compared to a homogeneous Generic Head Phantom and three high resolution anatomical head models with respect to specific absorption rate (SAR) assessment. The head phantoms are exposed to the radiation of a generic mobile phone (GMP) with different antenna types and a commercial mobile phone. The phones are placed in the standardized testing positions and operate at 900 and 1800 MHz. The average peak SAR is evaluated using both experimental (DASY3 near field scanner) and numerical (FDTD simulations) techniques. The numerical and experimental results compare well and confirm that the applied SAR assessment methods constitute a conservative approach.
Impact of human head with different originations on the anticipated SAR in tissue
The impact of human head with di®erent originations on the induced SAR owing to the RF emissions of di®erent cellular handset models is intensively investigated in this paper. Four homogeneous head phantoms with normal (non-pressed) ears are designed and used in simulations for evaluating the electromagnetic (EM) wave interaction between handset antennas and human head at 900 and 1800MHz with radiated power of 0.25 and 0.125 W, respectively. The Di®erence in heads dimensions due to di®erent origins shows di®erent EM wave interaction with cellular handsets.
SAR AND THERMAL EFFECT PREDICTION IN HUMAN HEAD EXPOSED TO CELL PHONE RADIATIONS
The wide deployment of cellular communications technologies make the cell phone one of the common sources of radio frequency(RF) radiations that cause in concerns about the probable health effects due exposure to RF radiations. As cell phone is usually hold next to the head of the user during conversations, hence, much attention must be paid to investigate the health effects produced due to interaction of head tissue with cell phone radiations. This aim of this work is to the implications of cell phone usage on human head through the use of a human head model that composed of multi layers. The human head model was simulated to evaluate the Specific Absorption Rate (SAR) and determine variation within the head exposed to RF radiations from the cell phone operating at 900 MHz.