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Every mobile phone emits radio frequency electromagnetic energy. The amount of this energy absorbed by the human head is measured by the specific absorption rate (SAR). There are standard limits, according to which phones sold should be below certain SAR level. To maintain these limits, shields can be used for the mobile phones. In this paper using...
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In the past several year's much attention has been paid to health implication of electromagnetic (EM) waves. With the increase in the number of mobiles phones and the longer periods these products used near the human body, concern has grown about the possible health hazards from exposure to electromagnetic radiation. One of the dominant effects cau...
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Citations
... MI/RF shielding is a method of reducing electromagnetic fields by erecting barriers of conductive or magnetic materials to stop them. Applying shielding to mobile phones [13] allows them to absorb the radiation being delivered through the air. To ensure that mobile phones remain unaffected by outside electromagnetic radiation, certain RF shields must be adhered. ...
Fifth Generation (5G) Technology, representing the latest advancement in wireless communication networks, has brought attention to the rising concerns regarding Specific Absorption Rate (SAR) due to temperature fluctuations. The negative impacts of SAR, particularly in the context of mobile users' head exposure, have prompted the exploration of effective mitigation strategies. This article introduces a novel approach, employing a Planar Inverted F-Antenna (PIFA) operating at 26 GHz, with the integration of RF shields, specifically a flexible ferrite sheet and a foam absorber, aimed at reducing SAR in the human head. Dosimetry investigations, conducted at frequencies exceeding 26 GHz, reveal that SAR values without shielding materials (1.59 W/kg) approach the safety limit of SAR. The incorporation of ferrite and foam absorber leads to SAR reductions of 1.53 and 1.48 W/kg, respectively. Notably, the proposed antenna demonstrates significant SAR Reduction Factor (SRF) values, particularly at 5G network frequencies (26 GHz). Comparative analysis highlights the superior performance of the foam absorber across various parameters. The prototype of the proposed antenna has been fabricated and subjected to testing, affirming its potential for alleviating SAR in the context of 5G technology.
... An additional model of the head consisting of four layers (skin, fat, skull, and brain) is used for this analysis. The thickness of these layers is (0.14 cm, 0.1 cm, 0.66 cm, and 8.1 cm) respectively [18]- [20]. Since mobile phones are typically placed with the face in such a manner that they appear flat with the head, layers of the head are considered flat layers. ...
Employing electromagnetic waves in mobile communication networks has increased the level of human exposure to electromagnetic fields that may result in concerns about health hazards associated involves the soaking up of cellular phone electromagnetic energy. The human body is penetrated by the electromagnetic fields that emit from a cell phone. The specific absorption rate (SAR) that is generated in the human head and body layers usually expresses the thermal effect on human tissue. The main objective of this paper is to investigate the thermal effects of the electromagnetic field induced inside the human head and body through the construction of a simplified model for both. The RF-source and human body models are built by using the ANSYS high-frequency structural simulator (HFSS). A planar inverted-F antenna (PIFA) will use to assign SAR values to different body tissues for the fourth generation (4G) of mobile phone communication at an operational frequency of 2.6 GHz and power radiated of 125 mW. The model is simulated and analyzed to evaluate the SAR induced at different human tissues depending on the source-to-antenna distance and its generated values must not exceed the safe limits for harmful thermal effects.
... Where is the body tissue conductivity (S/m), is the body tissue density (kg/m3), and E is the RMS value of the electric field strength in the tissue (V/m). SAR tests are only performed for 6 minutes of mobile phone usage; however studies have shown that individuals use mobile phones for several hours [17]. The spatial average of local exposure for general public SAR limit is 2 W/kg over 10g of tissues, according to ICNIRP standards [18].To avoid negative impacts on human health, SAR values must not exceed the threshold limits. ...
The phenomenon of radio frequency electromagnetic energy emitted from mobile phones is widely recognized, and the specific absorption rate (SAR) measures the amount of energy absorbed by the human head. To meet SAR standards, mobile phones can be shielded. This paper utilizes COMSOL Multiphysics to model the human head and simulate SAR distribution for various head layers exposed to radiation from a CDMA 800 downlink frequency band mobile phone. The study also observes electric and magnetic fields across the frequency range and investigate five different shielding materials. The results reveal that a polyimide sheet outperforms other materials according to ICNIRP guidelines for electromagnetic radiation exposure. These findings have significant implications for the design and production of mobile phones, as well as public health and safety.
... To evaluate the safe operation of the proposed method's SAR, the FCC-mandated basic fundamental exposure limit for whole-body exposure was determined over a tissue mass of 1 g. Conductivity (σ) and density (ρ) of the tissue are directly and inversely proportional to SAR, respectively, and that was estimated with the formula σ|E| 2 /ρ, where E is the electric field [28,29]. The United State's FCC now enforces a SAR limit of 1.6 W/kg over 1 g of tissue for the general population, and South Korea follows the same standard [30]. ...
Heart failure is a common, complex clinical syndrome with high morbidity and mortality. Hemodynamic parameter evaluation is useful for early detection, clinical outcome monitoring, timely treatment, and the overall prognosis of heart failure patients. Therefore, continuous monitoring of hemodynamic parameters helps in the evaluation of patients with suspected heart failure. The hemodynamic parameters change with respect to the contraction and expansion of the heart. Hence, in this research, two circuit-less 30 mm spherical receiver coils were implanted in both the left and right sides of the heart and an external transceiver coil was placed above the chest. The changes in the reflection coefficient of the transceiver coil at the resonant frequency changed depending on the distance between the implanted coils, allowing the contraction and expansion of the heart to be determined. This work was carried out at 13.56 MHz, considering the safety limits imposed by the FCC. The proposed reflection coefficient monitoring technique may distinguish healthy patients from heart failure and heart attack patients. The reflection coefficients at a maximum distance of 50 mm for simulation and measurement are −10.3 dB and −10.6 dB, respectively, at the resonant frequency.
... A typical solution for the design of body shields is the use of electrically conductive textiles that adhere to the body [3][4][5]. These are materials containing nano-additives [6] or, in simpler variants, composites containing metal plates [7] or multi-layer materials with controlled conductivity [8]. Such shielding structures cannot be used for screening eyes due to their opacity. ...
This article presents the design process of a structure that shields the electromagnetic field from the fifth-generation transmitter operating in the 3.5 GHz band. The purpose of this project is the limitation of power density in the eye region. For this reason, the structure is made of conducting wires forming a grid that is semitransparent to the light. The design was performed using computer simulations with a finite-difference time-domain method and an evolutionary-based optimization methodology. A simplified model of the face and eyes was developed to reduce the amount of time needed for the simulation. The construction of the shielding structure presented here can be easily fabricated in the form of protective goggles. The results of the computer simulations show that the power density in the eye region can be reduced by almost seven times compared with the unshielded case.
... They checked several shapes and sizes of aluminum shields to introduce SAR reduction of 20 % [15]. Hanafi et al. [18] studied numerically the effect of aluminum shield when placed on mobile model surface as shown in Fig.3 They obtained SAR reduction of 26.4 % [16]. ...
... They used several shielding materials including Copper, Aluminum, Teflon, and Germanium. The best of all is the germanium shielding, which reduced the SAR of the brain to 0.08 W/Kg [18]. Ragha et al. [21] studied the effect of the change in the shape and size of the RF shielding on the value of the SAR. ...
... The use of conductive sheet with PIFA antenna[18]. ...
... The reflection coefficients at the interfaces of the tissues are calculated by taking the impedances introduced by them under TE and TM polarization. Once the total transmission coefficient is calculated through the TLM, the SE can be determined [20][21]. ...
Nowadays, with the extensive use of mobile phones, the Electromagnetic (EM) radiation penetration from Radio Frequencies (RFs), particularly into the human head, is an issue that needs resolving. Some serious biological hazards occur inside the human body due to RF radiation accumulation. The RF radiation can be minimized by embodying shielding and coating materials on the front side of the mobile handset. The novelty of the proposed work is the use of mathematical analysis in calculating the Specific Absorption Rate (SAR) absorbed by planar four-layer adult and child head models when exposed to mobile smartphone RF radiation. The variation of SAR with the Angle of Incident (AoI) of the EM wave considers Transverse Electric (TE) and Transverse Magnetic (TM) Polarization. The SAR absorption alteration with the AoI of the EM wave is calculated with the help of the shielding effectiveness parameter of the external Polyethylene Terephthalate (PET) shield coated with conductive copper (Cu) mesh, forming a laminated shield using the methodology of the transmission line method. Furthermore, the SAR variation with AoI for both human head models is calculated theoretically at Sub-6 GHz mobile frequencies of 4.5GHz and 3.6GHz. SAR of 7.41e-12 W/kg and 4.41e-11 W/kg is achieved theoretically for adult and child head models respectively, at 89° TE polarization at 4.5GHz.
... In 2016, the modelling of the human head was performed in [109] using ANSYS HFSS (high-frequency structure simulator). For the simulation, the contemporary smartphone design was utilised. ...
... (a) (b) Figure 11. Thermal evaluation system for specific absorption rates: (a) system diagram, and (b) rectangular box-shaped semisolid phantom used for the measurements [109]. ...
Employing electromagnetic fields (EMFs) in new wireless communication and sensing technologies has substantially increased the level of human exposure to EMF waves. This paper presents a useful insight into the interaction of electromagnetic fields with biological media that is defined by the heat generation due to induced currents and dielectric loss. The specific absorption rate (SAR) defines the heating amount in a biological medium that is irradiated by an electromagnetic field value. The paper reviews the radio frequency hazards due to the SAR based on various safety standards and organisations, including a detailed investigation of previously published work in terms of modelling and measurements. It also summarises the most common techniques utilised between 1978 and 2021, in terms of the operational frequency spectrum, bandwidth, and SAR values.
... Here, σ w and ρ w are water-content dependent conductivity (S/m) and tissue mass density of WM, respectively. The value of ρ w is 1073 kg/m 3 [19,20]. ...
The proposed work focuses on the mathematical interpretation of Electromagnetic Shielding Effectiveness (ESE) of age-dependent human Head Models (HMs) of seven tissues (Skin, Fat, Bone, Dura, Cerebrospinal fluid (CSF), Gray matter, and White Matter) with the impact of the mobile phone holding position on the RF radiation absorption by the human head. The ESE is first simulated and estimated using the Transmission Line Method approach: a. for only layered human Head Models (HMs) in the absence of mobile position with variation in Oblique Angle of Incidence (OAI) in Transverse Electric Polarization (TEP) and Transverse Magnetic Polarization (TMP), b. in the presence of mobile phone position and Polarization. c. by incorporating the Transparent Conductive Metal Mesh Polyethylene terephthalate (PET) film (Copper grid PET Film) as a shielding material in the presence and absence of Polarization and mobile phone holding positions. The Copper grid PET Film is composed of optical PET film laminated with Copper (Cu) and Nickel (Ni) Transparent Conductive Mesh Coatings (TCMCs) to form a transparent laminated mesh. The radiation absorption characteristic, Specific Absorption Rate (SAR), is evaluated numerically at four Sub-6 GHz frequencies from the obtained ESE data to draw collation at the least SAR absorbed by the age-dependent HMs, considering the water contents of tissues. Out of adult and child HMs, the child HM absorbed the higher RF SAR. However, with the transparent PET/Cu/Ni Laminated Mesh (LM), at 5.47 GHz, the SAR by the brain’s white matter in child HM is highest in TEP with no shield considered is 10 W/kg. With transparent LM, the SAR obtained is 2.8e-12 W/kg in TEP in no mobile phone tilt condition at 89◦ OAI. With the user mobile tilt at 15◦ and 30◦, the SAR absorbed by the brain WM is 2.62e-12 W/kg and 2.1e-12 W/kg, respectively at 89◦. Hence, the SAR absorption is the least in any direction (azimuth or elevation) when the mobile phone is tilted to 30◦ in TE Polarization using the transparent PET/Cu/Ni laminated mesh. Therefore, the usage of transparent PET/Cu/Ni laminated mesh in TE Polarization saw the least SAR absorbed, whether the mobile phone is tilted either towards or away from the head when the mobile phone is moved to 15◦ or 30◦ tilted position.
... In the literature, the shielding structures applied for the human body are studied for the case when the cell phone is the source of electromagnetic radiation [4][5][6], while the development of multipurpose shielding materials assumes a plane wave [7,8]. The research carried out with respect to interactions of electromagnetic waves with the human body shows that both construction and the materials used for the human body shield design influence its performance. ...
... In [5], the shielding of cellular phone radiation with thin metal plates is studied, showing that the thickness and orientation of the plate influences the amount of energy absorbed by the head. The shielding material properties were identified in [6] for a particular mobile phone antenna and in this way the amount of energy absorbed by the human head was reduced. In the papers that focus on shielding material development, composites with improved conductivity are considered for this application. ...
The introduction of the fifth generation wireless systems caused social emotions regarding the impact of electromagnetic waves on people. Many people who consider themselves to be particularly sensitive to radiation make metal foil head covers (so called “tinfoil hats”) to shield their body from radiation. The aim of this paper is to show how effective the “tinfoil hat” really is when applied to base station radiation in a fifth generation telecommunication system. It presents the results of investigation on effectiveness of these protections in terms of their shielding properties at the frequencies used in fifth generation wireless systems. The research was carried out based on computer simulations. Remcom XFdtd software (software: XFdtd version 7.8.1 manufacturer: Remcom, 315 South Allen Street, Suite 416 State College, PA, USA) utilizing a finite difference time domain method and a numerical model of the head was applied to obtain the data on shielding properties of conductive head covers. It was found that in the case of foil head covers the maximum reduction factor of power density in the head region is approximately 50%. Furthermore, the application of a metal surface shield increases the maximum value of energy absorbed by human tissue in some regions of the head. To overcome this problem, the design of a wire-based shielding structure that does not reduce user comfort is presented as an alternative to the full-metal head cover.
For wave propagation in the horizontal plane, its performance is comparable to tinfoil-like structure, but its design makes it much more comfortable for the user.
