What is SAR testing? Is it only necessary for communication products?
What is SAR testing?
Specific Absorption Rate (SAR) testing is a radio frequency (RF) dosimetry method that quantifies the magnitude and distribution of electromagnetic energy absorbed within biological objects exposed to RF fields. Overexposure to radio frequency (RF) energy can damage human tissue. To prevent this As a result, many countries around the world have introduced standards that limit the amount of RF exposure allowed from all types of transmitters. Environmental Testing can help determine whether your product meets these requirements. We perform the necessary testing on a variety of portable and mobile telecommunications equipment. Environmental Testing is one of the few that can test your products against RF exposure standards as well as electrical safety standards and FCC requirements. One of the organizations that tests and certifies products.
RF exposure is assessed using a "phantom" that simulates the electrical properties of the human head or body. The RF energy passing through the "phantom" is monitored by a precisely positioned probe that measures SAR in Watts/kg of tissue, Federal Communications Commission Under 47 CFR Part 2, Section 2.1093, which regulates SAR, general use products must achieve a SAR limit of 1.6 mW/g averaged over 1 gram of tissue in the head or any part of the body, and over 10 averaged over the hands, wrists, feet, and ankles. 4 mW/g.
In the EU, Council Recommendation 1999/519/EC establishes RF exposure limits. Harmonized standards cover the most common products, such as mobile phones and RFID devices. The limits and methods for RF exposure assessment in the EU are similar but not identical to those in the United States. .
These levels are expressed in watts per kilogram (W/kg), and international regulatory agencies require SAR evaluation for most portable and mobile wireless technologies.
Parameters that can affect SAR include:
1. Type of radio service (cellular, PCS, LMR, WLAN, etc.)
2. Modulation type (CDMA, GMSK, TDMA, AMPS, etc.)
3. Orientation to the person's body (keep ear to ear, stay opposite, belt clip, lap, etc.)
4.RF power level (watts or milliwatts)
5. Changes in transmitter, antenna (extraction/retraction) or accessories (clips, batteries, etc.)
Maximum allowed exposure (MPE)
When the user is typically positioned away from the radio transmitter, typically more than 20cm, the RF exposure assessment method is called Maximum Permissible Exposure (MPE), and in many cases the MPE can be calculated based on transmitter output power and antenna type. In some cases, MPE must be measured directly in terms of electric or magnetic field strength or power density, depending on the operating frequency of the transmitter.