Specific absorption rate

SAR stands for Specific Absorption Rate; Unit: W / kg.

It is the physical size and the measure of the absorption of electromagnetic fields in the biological tissue. The absorption of electromagnetic energy field always leads to a heating of the tissue. The heating process corresponds to the dielectric heating.

Determination

The specific absorption rate can be calculated from

Here is:

Use

Frequently in mobile phones a SAR value is specified. This is modern appliances approximately 0.10 to 1.99 W / kg. The lower the SAR value, the lower the web is heated by the radiation. The recommended top limit of the World Health Organization is 2.0 W / kg. Previously, the SAR value for mobile phones has been designed by the manufacturers under heterogeneous conditions, which makes it very reliable. Since the fall of 2001, there is a European standard ( EN 50361 ), which sets the measurement conditions exactly. Since March/2007 EN 50361 has been replaced by EN 62209-1.

For the award of a mobile phone with the Blue Angels, a maximum SAR value of 0.6 W / kg is allowed. For the award of the TCO '01 Mobile Phone logo is a maximum SAR value of 0.8 W / kg is allowed.

The SAR value for mobile phones is specified for the maximum transmission power. Due to the power control but occurs mostly in operating a smaller SAR value, which is the particular mobile network dependent. Thus, the mobile phone sends in well developed networks with a high density of masts usually at a considerably lower transmission power than in bad developed networks. This means that the exposure when making calls in areas with a high density of transmission towers is lower than in areas with a low density of masts. Staying in vehicles and buildings (especially those made ​​of reinforced concrete ), however, increases the power output. The performance levels of conventional GSM mobile phones, depending on the reception situation between 1 and 2000 mW and produce within this range permissible SAR values.

The SAR value is only about the maximum transmission power of devices information. The average transmission power, however, lies low, since cell phones can vary its transmission power according to the reception situation. Thus, the SAR value for the statement of the actual radiated power is only partially meaningful.