How SAR is measured for devices
Each model of mobile phone or wireless device is tested using internationally agreed standards.
The SAR in the head is tested using a 'phantom' head and the SAR in the body is tested using a 'phantom' torso. The phantoms are filled with liquids that simulate the electrical properties of human tissue.
The SAR values are measured with the phone or device
- at maximum power
- at its different operating frequencies
- and in a range of positions.
A probe inside the liquid measures the electric field strength inside the phantom and uses this to determine the maximum SAR value for the model of phone or device in each particular configuration.
As a result, the testing is both complex and time consuming. For full compliance testing, the process can take up to several weeks depending on the model in question.
A video showing the SAR testing procedure is available at EMF Explained.