Specific Absorption Rate
SAR is the rate of RF energy absorption per unit mass in the body. SAR has units of joules per second per kilogram or watts per kilogram (W/kg).
This parameter is used as a primary indicator of RF- energy absorbed in the body when quantifying the biological effects and thus defining the basic exposure limits. At frequencies between 100 kHz and 10 GHz, SAR limits take precedence over field strength and power density limits and shall not be exceeded. When carrying out compliance evaluation, the SAR should be determined for cases where exposures take place at a distance of 20 cm or less from the source.
The SAR in a biological body exposed to an RF field depends on a number of factors including tissue geometry and dielectric properties and the orientation of the object relative to the source. Since the RF energy induced in the body is scattered and absorbed at various interfaces, the internal field and hence the SAR distribution is non - uniform.
The SAR measurement are carried out by scanning the tissue medium along the interior of a phantom with a robotically- controlled miniature E-field probe. Once the region of highest SAR is identified, algorithms are used to average over the prescribed volume to determine the peak spatial average. Different shaped phantoms and tissue mediums simulate the exposed part of the body for head and body worn equipment.
l: DASY4 SAR measurement system
- r: Phantom with cellular telephone in “body worn” mode
The ETS PS AG uses the professional SAR measurements system DASY 4 (from the Swiss supplier Schmid and Partner) for SAR evaluation.
This full automatic measurement system is approved by all national certification authorities. Featuers of DASY 4 are: 3-dimensional readouts with coloured zone indication, automatic calibration routines, peak detection and peak spatial-average SAR evaluation are detailed monitored and reported in the test documentation.
Different phantoms and tissue mediums enable our lab to SAR tests for radio base stations, fixed terminal stations for wireless communication systems and related antennas according to all major RF exposure standards. Furthermore general RF exposure routines can be evaluated by our experts and reported with a “RF - Exposure Consideration Document”.
- l: DASY4 readout simulation in phantom’s head
- r: Zone - simulation of an Radio module
SAR testing is required primarily for: cellular phone, PDA, headset, laptop, PC-card,...
Regional SAR Requirements:
R&TTE directive article 3.1a, “…the protection of the health and the safety of the user and any other person …”. | ||
EN 50360:2001 | Product standard to demonstrate the compliance of mobile phones with the basic restrictions related to human exposure to electromagnetic fields (300 MHz - 3 GHz) | |
EN 50361:2001 | Product standard to demonstrate the compliance of mobile phones with the basic restrictions related to human exposure to electromagnetic fields (300 MHz - 3 GHz) | |
EN 50371:2002 | Generic standard to demonstrate the compliance of low power electronic and electrical apparatus with the basic restriction related to human exposure to electromagnetic field (10 MHz - 300 GHz) - General Public | |
EN 50383:2002 | Basic standard for the calculation and measurement of electromagnetic field strength and SAR related to human exposure from radio base-stations and fixed terminal stations for wireless telecommunication systems (110 MHz - 40 GHz) | |
EN 50384:2002 | Product standard to demonstrate the compliance of radio base stations and fixed terminal stations for wireless telecommunication systems with the basic restrictions or the reference levels related to human exposure to radio frequency electromagnetic fields (110 MHz - 40 GHz) - Occupational | |
EN 50385:2002 | Product standard to demonstrate the compliance of radio base stations and fixed terminal stations for wireless telecommunication systems with the basic restrictions or the reference levels related to human exposure to radio frequency electromagnetic fields (110 MHz - 40 GHz) - General public | |
47CFR 2.1091 and 2.1093 | ||
FCC OET Bulletin 65, Supplement C (portable transmitting devices) | ||
IEEE 1528:200X | Recommended Practice for determining the peak Spatial - Average Absorption Rate (SAR) in the Human Body Due to Wireless Communications Devices: Experimental Techniques | |
Health Canada’s Safety Code 6 | ||
RSS-102 Issue 2 | Radio Frequency Exposure Compliance of Radio communication Apparatus (All Frequency Bands) | |
Radio communications (Electromagnetic Radiation - Human Exposure) Standard 2003 | ||
RPS No. 3 | Radiation Protection Standard | |
International: | IEC 62209 | Human exposure to radio frequency fields from hand-held and body-mounted wireless communication devices - Human models, instrumentation, and procedure |
For further information, please contact our ETS PS specialists.
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