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The mystery of SAR testing: How does a mobile phone perform a "physical examination" on the head?
In today's era of rapid technological development, mobile phones have almost become an indispensable part of people's lives. As people spend more time using mobile phones, the impact on their physical health has also attracted widespread attention. In particular, the measurement of radio frequency (RF) energy absorbed by the human body when the mobile phone is used close to the head becomes an important issue. This measurement is called the Specific Absorption Rate (SAR).
SAR is a measure of the rate at which energy per unit mass is absorbed by the human body when exposed to radio frequency electromagnetic fields.
Basic concepts and calculation of SAR
The definition of SAR seems simple, but it actually involves a complex calculation and evaluation process. This value is often used to assess energy absorption in different parts of the human body. Lighter parts of your body may absorb more energy, while heavier parts absorb relatively less. The calculation of SAR involves factors such as electric field strength, conductivity and density of the sample, thereby ensuring that the measured data can accurately reflect the actual situation.
SAR testing is not only used in mobile phones, it also plays an important role in MRI scans.
How to conduct SAR test on mobile phones?
In order to accurately measure the impact of mobile phones on the human body during use, the test equipment will be carried out on a device that simulates the human head. This device is often referred to as the "SAR Phantom". The phone is placed in this simulated head conversation position, and the results are displayed where the signal is received, usually near the phone's antenna.
Governments in different regions set different SAR limits for the RF energy emitted by mobile phones.
Differences in SAR standards around the world
In the United States, the Federal Communications Commission (FCC) sets the SAR limit at 1.6 W/kg, while in Europe it is 2 W/kg, measured on 10 grams of tissue. As reports mounted, India turned to U.S. standards, which include a random testing strategy for test devices to ensure the safety of all handheld devices on the market.
SAR test specifications in MRI scanning
When using MRI for diagnosis, the testing standards for SAR are different from those for mobile phones. Under the IEC 60601-2-33 standard, MRI SAR testing includes some dynamically adjusted scales, and some test standards may be adjusted based on the patient's weight data.
Criticisms of the SAR Standard
While government agencies set standards for SAR limits, critics point out that these standards may not fully reflect the human body's sensitivity to RF energy. The report noted that some human responses to the auditory effects of microwaves are within the legal SAR limits.
Experts recommend that the most effective way for mobile phone users to reduce RF energy absorption is to keep the phone away from the body and use a hands-free device.
Summary and Outlook
Although current technology allows us to use mobile phones more conveniently, we also need to pay attention to the health problems that come with it. SAR testing is gaining increasing attention, not only to meet legal requirements, but also to protect the health of users. Against this backdrop, governments, manufacturers and consumers should not take mobile phone usage and safety standards lightly. Should we pay more attention to the potential health risks posed by these invisible electromagnetic fields?
