Measurement of Specific Absorption Rate

Measurements from body-mounted devices

A parameter of major importance in the quantification of human exposure to electromagnetic (EM) radiation is the Specific Absorption Rate (SAR) of power from EM signals into human tissues, a quantity measured in watts per kilogram. Traceable dielectric measurements are an essential part of SAR metrology as it is effectively focused on the interaction of EM fields with biological dielectrics, such as people.

NPL provides measurement of the SAR from body mounted devices to IEC62209-2 and FCC OET-65. Testing can be performed in head or muscle simulating liquids and we are able to test devices over the frequency range 20 MHz to 6 GHz for peak, and 1 g or 10 g for averaged, SAR.

The system has been used for a variety of development and testing purposes including the measurement of antennas used to treat cancer tumours by hyperthermia and development of fabric antennas in T-shirts. Measurement of SAR is also important in medical diagnostics, such as Magnetic Resonance Imaging, and in RF and Microwave processing, where significant RF fields can be generated and safe working environments need to be guaranteed for employees.

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