ITU- International Telecommunication Union
International Committee on Non-ionizing Radiation Protection
China National Laboratory Accreditation Committee
FCC- us federal communications commission
Who- international health organization
International association of electronic and electrical engineers
Explanation of terms-China Tell Laboratory-
Under the Ministry of Information Industry, it was established in 198 1, formerly known as "China Telephone Reference Equivalent Testing Center", which was jointly approved by the former Ministry of Posts and Telecommunications and the State Bureau of Standards. On June 5438+1October 65438+February, 2000, with the joint approval of the State Bureau of Quality and Technical Supervision and the Ministry of Information Industry, the laboratory was officially renamed as "China Taier Laboratory". It has become a large-scale comprehensive national laboratory for the research of telecommunication technical standards and test methods and the inspection and test of telecommunication equipment in China.
The "Safety Protection and Electromagnetic Compatibility Testing and Research Department" under Thiel Laboratory is the authoritative testing institution for telecom product network access certification designated by the Ministry of Information Industry. As the most authoritative organization in the communication field, emc Laboratories has been recognized by China National Laboratory Accreditation Committee (CNACL), DAR, European Laboratory Accreditation Organization and FCC, and is responsible for providing electromagnetic compatibility and electromagnetic radiation testing, consulting and arbitration services for domestic and foreign institutions and customers.
It has the most advanced electromagnetic dose evaluation system in the world and the only one in China, which can measure the radiation produced by mobile phones to human electromagnetic radiation.
Noun interpretation
SAR is the abbreviation of specific absorption rate, namely "absorption ratio". It is the electromagnetic absorption radiation energy absorbed by a unit mass of matter in a unit time.
Generally speaking, it is to measure whether the influence of mobile phone radiation on human body is up to standard. At present, the international standard is that the absorbed electromagnetic radiation energy per kilogram of brain tissue should not exceed 2W, calculated in 6 minutes. This standard is a common standard in the international industry.
According to two experts, Wang Nan and Ma Xin, who are experts in electromagnetic radiation measurement and deputy directors of China Tire Laboratory, only SAR value is the only standard to measure the radiation of mobile phones.
What is mobile phone radiation and its classification?
When people use a mobile phone, the mobile phone will send radio waves to the transmitting base station, and any kind of radio waves will be absorbed by the human body more or less, which is called mobile phone radiation.
Mobile phone radiation can be divided into two types:
-Cell phone fuselage radiation
-base station radiation
Radiation test standard for mobile phones
1990, IEEE formulated the technical standard for electromagnetic radiation measurement of mobile phones. 1998 ICNIRP (International Commission on Non-ionizing Radiation Protection) has also formulated similar technical standards, in which SAR is used to measure the electromagnetic radiation of mobile phones.
ICNIRP standard is recommended by ITU (International Telecommunication Union) and WHO (International Health Organization) and supported by most countries. The FCC in North America adopts IEEE standard, and industry organizations such as CTIA in the United States also suggest marking SAR value on mobile phone packaging.
At present, the Joint Working Group on the Formulation of National Standards for Electromagnetic Radiation led by AQSIQ, together with the National Institute of Metrology, the Ministry of Health, the Environmental Protection Bureau, the Ministry of Information Industry and other departments, is jointly formulating China's electromagnetic radiation protection standards, among which SAR is also used as the basic limit for measuring mobile phone radiation.
How is the SAR value measured?
● Tissue measurement systems, such as manikin, measuring instruments, probes and mechanical arms. The system is placed in the shielding room. The interior of the mannequin is a liquid substance, and the electromagnetism of the liquid is consistent with that of the human body, and the probe can move freely in it.
● The measurement unit of test standard adopted in Europe is10g (recommended by ITU), and that of the United States is1g..
● Place the mobile phone close to the model, so that the mobile phone is in the state of maximum transmission power.
The mechanical arm automatically measures the field strength e.
● Calculate SAR by the following formula:
SAR=(δ/р) E2
Where, р: liquid density; δ: dielectric constant; E: field strength.
Radiation standard for mobile phones (SAR limit)
According to the requirements of SAR value, the technical standard for measuring the radiation of mobile phones recommended by the International Telecommunication Union and the International Health Organization, the electromagnetic radiation of GSM and narrowband CDMA mobile phones must be within the allowable range certified by the international authoritative health organization.
The ITU standard limit is 2.0W/KG, and the FCC standard limit is 1.6W/KG.
Basic conclusions of international authorities on mobile phone radiation-1
International practice takes SAR as the basic limit to measure the radiation of mobile phones;
The measurement of mobile phone radiation cannot be carried out in the air.
Basic conclusions of international authoritative organizations on mobile phone radiation -2
Any wireless transmitter will produce electromagnetic radiation. From this perspective, pure "green mobile phones" do not exist.
At present, the radiation limit of mobile phone stipulated in the standard is generally 50 times smaller than the radiation dose that may cause danger. Therefore, mobile phones that meet the standards are safe.
According to the World Health Organization, there is no evidence that using mobile phones will harm human health.
Basic conclusions of international authoritative organizations on mobile phone radiation -3
The SAR value of each mobile phone mainly depends on its antenna, design and other factors, rather than the network technology or technical standards of mobile communication. As far as different brands of mobile phones and different models of the same brand are concerned, their radiation is very different, and may even be dozens of times different.
Reasons for the difference of specific absorption rate of different types of mobile phones
Weasion Wei, chief engineer of China Thiel Laboratory, believes that the reason why SAR values of different types of mobile phones are quite different is related to the distance between electromagnetic radiation sources and human bodies.
From the perspective of transmission power, all mobile phones are at the same level. Generally, the maximum power of GSM mobile phone is 2W (the actual average power is 0.25W due to TDMA technology), and the maximum power of CDMA mobile phone is1w.. The distance between electromagnetic radiation source and human body becomes the decisive factor to determine SAR value. The value of 1mm SAR will increase a lot every time the radiation source approaches. Therefore, all mobile phone manufacturers are trying to improve this aspect and try to keep the mobile phone antenna as far away from the human body as possible.