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Do you know the SAR value of your mobile phone? The amazing testing process behind the discovery!
In today's increasingly technologically advanced world, mobile phones have become an indispensable part of people's lives. However, with the popularity of mobile phones, we also have to face the security issues that come with it. In particular, the impact of electromagnetic waves emitted by mobile phones on the human body has attracted much attention, and the most important indicator is the SAR value (specific absorption rate). So, do you know the SAR value of your mobile phone?
Definition of SAR value
The SAR value is a measure of the rate of energy absorbed by the human body per kilogram of body weight when exposed to radio frequency (RF) electromagnetic fields. It is measured in watts per kilogram (W/kg) and is usually calculated as an average over the whole body or a small sample volume (such as 1 gram or 10 grams of tissue). The SAR value reflects the maximum electromagnetic energy absorbed by a certain part of the human body within a specific volume or mass.
SAR calculation
SAR can be calculated using the following formula:
SAR = 1/V ∫sample (σ(r) |E(r)|² / ρ(r)) dr
In this formula, σ is the conductivity, E is the electric field strength, ρ is the sample density, and V is the volume of the sample. SAR is mainly used to measure the electromagnetic energy emitted by mobile phones and the energy absorption of the human body during MRI scanning. The test must be conducted for each specific electromagnetic source.
Mobile phone SAR test process
When testing the SAR value of a mobile phone, the mobile phone will be placed on a model that simulates a human head (i.e. SAR Phantom) for testing. During the test, measurements are taken at the location of the head where the absorption rate is highest, usually near the phone's antenna. In addition, the test will cover signals of different frequencies to meet the various transmission needs of the device.
Government SAR standards
Governments of various countries have clear regulations on SAR values. For example, the United States requires that all mobile phones sold have a SAR value below 1.6 W/kg, which is based on a test of 1 gram of tissue. The European Union uses 10 grams of tissue as a benchmark and sets an upper limit of 2 W/kg. India changed the standards to U.S. requirements in 2012 and also conducts random compliance testing.
SAR test of MRI scan
When performing MRI scans, SAR testing is also relatively complex. The standards dynamically adjust for exposed patient weight and device usage patterns. Generally speaking, the local SAR is set to 10 W/kg, and it is adjusted according to the actual situation to ensure patient safety.
Criticisms of SAR standards
Despite many safety guidelines, limits on SAR values do not take into account the human body's sensitivity to certain frequencies. Many experts have pointed out that when the human body is exposed to electromagnetic waves of specific frequencies, microwave hearing effects will occur. The triggering power density of this effect is relatively low. At the same time, long-term environmental exposure must also be taken seriously, and the usual limit is 0.08 W/kg.
FCC’s recommendations
The U.S. Federal Communications Commission (FCC) emphasized in its guidance document that all mobile phones must meet RF exposure standards that are well below levels that would cause health problems. For users concerned about these standards, the FCC recommends using speakers or hands-free devices to reduce the radiation absorption of mobile phones.
Study future trends
As research on the health effects of electromagnetic waves continues, the biological effects of minimum SAR (MSBE) immediate absorption have become increasingly important. These studies aim to reveal the effects of low-intensity electromagnetic radiation and help the scientific community understand the limits of the effects of non-ionizing radiation. At the same time, this may also lead to a better understanding of cellular responses, thereby improving our preparedness for dealing with electromagnetic radiation.
Conclusion
As technology continues to advance, our safety requirements for mobile phone use are also constantly increasing. It is the responsibility of every consumer to understand the SAR value of his or her mobile phone. When choosing a mobile phone, in addition to considering functions and price, you should also pay attention to its impact on health. Do you think the SAR value of mobile phones can really protect our health?
