SAR Values for Mobile Phones
SAR stands for specific energy absorption rate. The SAR value of a mobile phone is the maximum amount of transmitted power the body will absorb during the use of the mobile device. The legal limit is 2 watts per kilogram body tissue, which is in line with the recommendations of the International Commission on Non-Ionizing Radiation Protection (ICNIRP). All mobile phones sold in Germany and Europe must comply with the SAR limit.
Mobile phones are designed in a way to not just comply with the maximum limits but to remain well under them. The SAR values stated in the table correspond to the maximum values measured according to the European standard. During the actual use of the mobile, these values are generally much lower because of the automatic power regulation of mobile phone networks.
The influence of radio waves on the human body has been the subject of extensive research on the national and international level for several years. Many scientific studies have shown that there are no damaging effects on the health as long as the legal limits for electromagnetic fields are observed.
How is the SAR value determined?
The SAR measuring method verifies a mobile phone’s compliance with the legal limit. All mobile phones currently available on the market safely stay within this limit.
SAR values are measured using specific test standards: European standard EN 50360 for the use of mobile phones held to the ear and guideline OET65/C of the Federal Communications Commission (FCC) in the United States for the operation close to the body (e.g., when carried on a belt clip).
The SAR value at the head is measured using a 2 millimetre thick plastic shell in the form of a head. It is filled with a special liquid that simulates the electromagnetic properties of head tissue. The mobile phone, which is transmitting at maximum power, is placed at the “ear” of the plastic head. A probe below the head then measures the distribution of the SAR in the liquid. The distribution is used to calculate the maximum SAR value averaged for 10 grams of tissue. The resulting value is then compared with the upper limit.
The SAR value stated in compliance with the standard test is based on the maximum possible transmitting power of a mobile phone. In general, however, the actual SAR value during a call is considerably lower than the value determined in the standard test. The reason for this difference is the ability of the mobile phone network to adapt its power to the required demand at the time. As a result, mobile phones will always transmit with only the minimum power necessary. On average, this level lies far below the maximum possible transmission power. The power transmitted by the mobile phone is also lower, the closer it is to the base station and the better the mobile network is developed.
When using mobile phones close to the body or using accessories, the manufacturer’s information and specific safety instructions should be observed.