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Bringing a new wireless communication device to market comes with a list of requirements and regulations to be aware of from the design phase all the way through to launch. One of these requirements has to do with the safety of consumers when using a wireless device.
SAR is short for specific absorption rate. This unit of measurement is used to determine the amount of radio frequency, RF, energy that gets absorbed by the human body. While products such as walkie talkies and antennas that transmit radio communication have measurable SAR, mobile phones are the most common sources of RF energy.
What Are the Limits for SAR Measurements?
Electromagnetic fields, or EMFs, have international guidelines on what is considered safe exposure to RF energy. The guidelines take into account all ages of potential device users to protect them against negative impacts to their health. SAR is measured in watts per kilogram, notated as W/kg.
Internationally, the general SAR limites are:
- 0.08 W/kg for whole-body exposure
- 2 W/kg for localized exposure to the head and body
- 4 W/kg for localized exposure to limbs
It’s important to note that certain countries may have their own limits set. For example, Canada and the US have a 1.6 W/kg limit for head and body exposure.
How Are SAR Measurements Captured?
In order to achieve the needed environment for accurate SAR testing, a specialized laboratory setting is required. The tests use a container that resembles the shape and size of an average human body filled with what’s known as tissue-equivalent liquid.
The wireless communication device is then operated while placed against the container. Sensor probes monitor RF energy at various locations within the head and body with an external computer analyzing the data and recording the maximum SAR value experienced.
Are SAR Levels Constant During Use?
The amount of RF energy produced during lab testing is done at maximum power based on the certified power level of the device. For most consumer uses, the SAR levels will be far below the resulting values as most communication devices will use as little power as possible to maintain proper voice quality.
In mobile phones, the highest SAR levels are found when establishing a connection over a cellular network. Once the call has begun, the device leverages adaptive power controls to lower battery consumption and RF energy emitted.
Minimizing SAR levels can be accomplished by being closer to the cell tower or base station supporting the wireless communication. Users concerned about EMFs and SAR levels are able to verify the maximum SAR of any device prior to purchase.
Where Can I Find SAR Testing Services?
Compliance Testing is one of the few laboratories in the US equipped to measure SAR at all levels. Whether it’s a commercial or consumer device being prepared for the market, Compliance Testing can provide testing and regulation guidance to get your products ready for certification.
If you’re interested in exploring the wireless communication market, reach out to our team to schedule a free risk assessment today.
