China
Africa
Explore chapters and articles related to this topic
Physical Aspects of Radiofrequency Radiation Dosimetry
Published in Marko Markov, Dosimetry in Bioelectromagnetics, 2017
Marko S. Andjelković, Goran S. Ristić
A second basic technique for measuring SAR is to measure the temperature change due to heat produced by the radiation, and then to calculate the SAR from that. Probes inserted into experimental animals or models can measure local temperatures, and then the SAR at a given point can be calculated from the temperature rise. Such a calculation is easy if the temperature rise is linear with time; that is, the irradiating fields are intense enough so that heat transfer within and out of the body has but negligible influence on the temperature rise. Generating fields intense enough is sometimes difficult. If the temperature rise is not linear with time, calculation of the SAR from temperature rise must include heat transfer, which is much more difficult. Another problem is that the temperature probe sometimes perturbs the internal E-field patterns, thus producing artifacts in the measurements. This problem has led to the development of temperature probes using optical fibers or high-resistance leads instead of ordinary wire leads.
Mobile Communication Fields in Biological Systems
Published in James C. Lin, Electromagnetic Fields in Biological Systems, 2016
Konstantina S. Nikita, Asimina Kiourti
Lists of SAR values for different phones are published on various Web pages and values ranging from 0.1 to 1.8 W/kg can be found. Similar results have been reported in Ali et al. (2007) for 21 different phones, with the 10 g avg SAR ranging from 0.3 to 1.7 W/kg. Kuster, Kastle, and Schmid (1997b) measured 16 different European digital phones and found a very wide variation in the SAR values. The phone with the lowest value, when averaged over a 10 g tissue, had a SAR of 0.28 W/kg and the one with the highest value had 1.33 W/kg, all normalized to an antenna input power of 0.25 W. If the averaging was done over 1 g of tissue, the SAR value went from 0.42 W/kg to 2 W/kg. However, when the phone was slightly tilted toward the head of the user, the value went from a low of 0.2 to a high of 3.5 W/kg.
Interaction of Nonmodulated Radio Frequency Fields with Living Matter: Experimental Results
Published in Charles Polk, Elliot Postow, CRC Handbook of Biological Effects of Electromagnetic Fields, 2019
An effort is being made to standardize dosimetric measures of RF exposure by employing a quantity called the SAR, The unit-mass, time-averaged rate of RF energy absorption is specified in SI units of watts per kilogram (W kg-1).34 The amount of energy absorbed by a given mass of material, which is termed specific absorption (SA), i.e., Joules per kilogram (J/kg), is the product of SAR times the duration of exposure (in seconds). Thus, the specific absorption rate (SAR) is the time rate at which RF electromagnetic energy is imparted to a component or mass of a biological body. The SAR is applicable to any tissue or organ of interest, or is expressed as a whole-body average.
Investigations on the enhancement of thermomagnetic properties in Fe2.4Ga0.6O4
Published in Phase Transitions, 2023
K. Rećko, M. Orzechowska, W. Olszewski, A. Beskrovnyy, M. Biernacka, U. Klekotka, A. Miaskowski, K. Szymański
Non-adiabatic calorimetric measurements are connected with the loss of thermal energy to the environment. Moreover, the heating characteristics of magnetic nanoparticles largely depend on the exposed frequency (f) and magnetic field strength (H) (unpublished data). The ability of magnetic nanoparticles to heat is usually quantified by the specific loss power, which can be estimated from calorimetric measurements (see Figure 6(a)). The specific loss power known also as specific absorption rate (SAR) can be defined as the thermal power per unit mass dissipated by the magnetic material. Alternatively, the SAR is defined as the heating power generated per unit mass of tissue when the human body is exposed to radiofrequency electromagnetic field. Measures of the magnetic heating ability of magnetic nanoparticles are specific loss power and intrinsic loss power.
Utilization efficiency of microwave energy for granular food in continuous drying: From propagation properties to technology parameters
Published in Drying Technology, 2022
Lei Wang, Yueming Zhao, Wenyu Ma, Liuyang Shen, Chenghai Liu, Chai Liu, Xianzhe Zheng, Shilei Li
Absorption of microwave energy inside GBR material layer depends on the dielectric properties of material processed and the distribution of electric field strength in material layer. Specific absorption rate (SAR) is defined as the absorption or consumption of microwave energy within unit mass of material processed (W/kg) as Eq. (16) where m is the mass of material processed (kg), V is volume (m3), is the density of material processed (kg/m3). In the microwave drying process, SAR was introduced to characterize the change of microwave absorption inside material processed, which reflects the impedance matching between the waveguide in the microwave cavity and the load.
Designing and performance evaluation of metamaterial inspired antenna for 4G and 5G applications
Published in International Journal of Electronics, 2021
Harbinder Singh, Balwinder Singh Sohi, Amit Gupta
According to the FCC guidelines, the maximum SAR is restricted to 2 W/kg averaged over 10 g of human tissue and 1.6 W/kg averaged over 1 g of human tissue. The averaging method used in this analysis is as per the IEEE C95.3 standard. The SAR is analysed at 100 mW of input power for 1 g of tissue at a distance of 1 mm from the human head.