SAR analysis in a realistic grounded human head for radiating dipole antenna (original) (raw)
Related papers
International Journal of Microwave and Optical …, 2009
Analysis of specific absorption rate (SAR) generated by half wave radiating dipole antenna inside a spherical inhomogeneous human head model at the frequency range 500 MHz to 3 GHz using finite difference in time domain (FDTD) method is presented in this paper. The human head is modeled as an inhomogeneous sphere of 19 cm diameter consisting of a uniform core representing human brain, surrounded by two spherical shells representing skull and skin with their respective electromagnetic properties. Maximum local SARs are obtained for the distance between head and antenna in the range of 1.0 cm to 3.0 cm using a dipole antenna of length 14.5 cm. As the distance is increased over 1.0 cm then the value of maximum local SAR induced in the head goes below FCC and IEEE's upper safety limit for input power of 0.6 Watt. Resonant dipole antennas of appropriate length corresponding to several spot frequencies have also been used to observe the maximum local SARs at their resonance frequencies.
Specific absorption rate (SAR) inside spherical human head model for half-wave radiating dipole antenna has been investigated at the frequency range from 500 MHz to 3 GHz using finite difference in time domain (FDTD) method. The effects of variation of reflection coefficient and resonant frequency of the antenna due to presence of head model are also presented in this paper. The human head is modeled as inhomogeneous sphere of 19 cm diameter consists of a uniform core representing human brain, surrounded by two spherical shells representing skull and skin. Distance between the head and antenna is varied from 1 cm to 3 cm to calculate the maximum local SAR induced inside the head. At some frequencies the maximum local SAR becomes more than the FCC and IEEE's upper safety limit for the distance between the head and antenna less than 1 cm and 0.6 Watt radiated power.
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.
National Conference on Communications, IIT Bombay, …, 2008
Investigations have been carried out on specific absorption rate (SAR) for a human head exposed to electromagnetic waves irradiated from a half-wave dipole antenna at the frequency range from 500 MHz to 5 GHz using finite difference time domain (FDTD) method. For simplicity, the human head is modeled as a rectangular cube consists of 40×40×50 Yee cells and the dielectric constant and conductivity of human head are assumed to be homogeneous. Distance between the head and dipole antenna is varied in the range of 1.0 cm to 3.0 cm to calculate maximum local SARs. It is found that the maximum local SAR induced in the head is below the FCC and IEEE's upper safety limit when distance of the head from the dipole antenna is more than 1.0 cm.
Estimation of Whole-Body Average Sar in Human Body Exposed to a Base Station Antenna
Progress In Electromagnetics Research M, 2014
Electromagnetic wave absorption inside a human body is investigated. The human body has been modeled using 3D voxel based dataset considering different electrical parameters. At GSM 900 band, Specific Absorption Rate (SAR) induced inside the human body model exposed to a radiating base station antenna (BSA) has been calculated for multiple number of carrier frequencies and input power of 20 W/carrier. Distance (R) of human body from BSA is varied in the range of 0.5 m to 5.0 m. Values of whole-body average SAR obtained by hybrid FDTD method closely match with that obtained by SFDTD method. For number of carrier frequency equal to five and R = 0.5 m, maximum value of whole-body average SAR obtained by both hybrid FDTD and SFDTD method is found to be 0.69 W/kg which decreases either with increase of R or decrease of number of carrier frequencies. Safety distance for general public is found to be 1.5 m for number of carrier frequencies equal to five. Summary of performance comparison shows that hybrid FDTD method is faster and requires less memory than SFDTD method.
SAR Analysis in Human Head Tissues for Different Types of Antennas
2010
The aim of this paper, a comparative study of several antennas commonly used in portable telephones is investigated. These include a monopole, a helical, a patch and a PIFA antenna. Each one of these structures is modelled and numerically tested using CST Microwave Studio. The testing procedure involves antenna simulation in the proximity of the human head and hand. The behavior of each antenna is evaluated for variable distances from the head geometry (0-20 mm). The simulation outputs used as measures for this comparative study include the specific absorption rate (SAR). The computed SAR levels within each of the considered tissues vary for the four antennas under investigation and are within the determined health safety standards.
Progress In Electromagnetics Research M, 2014
This study proposes an accurate estimation of whole-body averaged specific absorption rate (WBA-SAR) for far-field exposure of an isolated human body in the frequency range of 10-200 MHz based on a lossy homogenous cylindrical antenna model of the human body. Equations are derived for the total induced axial current and the whole-body averaged SAR based on a rigorous treatment of cylindrical antenna theory. An explicit formula for the resonance frequency in terms of the anatomical parameters and the dielectric properties of the body is proposed for the first time. Moreover, important phenomena in far-field radio frequency (RF) dosimetry, such as, the cause of resonance and the SAR frequency characteristics are discussed from an antenna theory perspective.
Case Studies in Thermal Engineering, 2020
Wearable metal objects with high electromagnetic reflection characteristics can cause interference with the incident waves during exposure to the electromagnetic (EM) radiation. Therefore, it is of interest to investigate the effect of metal objects capable of increasing the absorption of EM energy and temperature within the tissues when get exposed to EM radiation. A numerical analysis of increase in specific absorption rate (SAR) and temperature distribution in a human head model when metal objects are placed between the head and radiating source is performed. A realistic three-dimensional heterogeneous human head model, metal objects of different shapes and sizes, and spectacles with different lenses are used. A half-wavelength dipole antenna operating at 1800 MHz served as an EM radiation source. Results show that the presence of metal objects in proximity to the head alters SAR and temperature increase within the tissues. In most cases, metal objects redistribute the EM field incident upon them to a smaller region increasing power absorption, thereby increasing SAR and temperature in that region. The power absorption in head layers is found to be sensitive to metal object's size and shape, and distance of the antenna from the objects.
SAR Simulation in Human Head Exposed to RF Signals and Safety Precautions
2013
As the number of mobile phone users is increasing rapidly, it has become main concern to focus on the effect of radio frequency electromagnetic radiations produced by mobile phone. At communication frequency, human body behaves as a dielectric and the EM radiation generated by mobile phone are able to penetrate through semisolid substances like living tissues and meat etc. The EM radiation is called the fourth pollution source besides air, water and noise by the environmentalists. And that how to protect against it and calculate it grows to a primary problem. In this paper, the maximum Specific absorption rate (SAR) averaged over 1g and 10g of tissue inside homogenous human head model has been investigated for dualband PIFA antenna operating in the 900 MHz and 1800 MHz frequency bands. The human head model consists of a uniform core representing human brain, surrounded by shell representing head skull and skin. All Simulations are performed using CST-Microwave studio. The provided a...
2018
─ Temperature rise and specific absorption rate distribution in a human head due to electromagnetic energy produced by an adjacent antenna are evaluated. An algorithm proposed in this paper provides these distributions at multiple frequencies using a single simulation. The head tissue parameters are used from the available three-term Debye coefficients obtained by the experimental data from 500 MHz to 20 GHz. The proposed algorithm is developed by integrating the Debye model of human head tissues parameters into the finite-difference time-domain method by using the auxiliary differential equation approach along with the use of bioheat equation for specific absorption rate and temperature computations. Index Terms ─ Dispersive material, FDTD method, Specific Absorption Rate (SAR), temperature rise.