What is SAR (Specific Absorption Rate)?

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What is SAR (Specific Absorption Rate)?

For anyone interested in learning more about SAR, or who has the question “What is SAR?” on their mind, we’re taking an introductory look at Specific Absorption Rate in this article. 

We all know that wireless devices need to use electromagnetic radiation to perform. However, most of us are likely unfamiliar with what SAR actually is in relation to this radiation, how it’s calculated, and who sets these limits. Keep reading to get all of your questions regarding SAR answered. 

What is SAR?

Specific absorption rate, or SAR, is a measure of how much radiation is absorbed by the human body when devices that emit RF energy are operated. SAR provides a simple way to evaluate the safety of wireless devices following guidelines set by regulatory bodies such as the FCC. 

SAR describes the amount of RF energy absorbed by the body from wireless devices and the rate at which it’s absorbed by the tissue exposed to it. SAR value is measured by watts per kilogram (W/kg) or milliwatts per gram (mW/g). 

How is specific absorption rate determined?

Using models of the human head and body filled with liquid to mimic tissues in the body, wireless devices are tested in ways that simulate how they are used. During testing, these devices are also operated at their highest power level in multiple frequency bands. 

For example, a cell phone is tested by being held up against the model of a head to mimic how it would be used. When the phone is in this position, a robotic probe measures the electric field at specific locations within the model’s head and torso. The highest SAR values for each frequency band of operation are included in a report to regulatory bodies to prove that the device conforms to all RF exposure guidelines. 

Who determines safe SAR limits?

SAR exposure limits vary between countries. In the US, mobile devices are required to meet a limit of 1.6 W/Kg measured from a 1 g tissue volume. For devices to gain FCC certification and be sold in the US, their maximum RF exposure level cannot exceed this. This applies to SAR regulations for other countries as well, such as the EU and Canada.

In the European Union, the SAR limit of devices is 2.0 W/Kg measured from a 10 g tissue volume.

Canada’s SAR regulations are the most stringent because they include CE and FCC certification requirements along with requirements of their own. This complicates the process of obtaining certification in Canada. Just like in the US, Canada requires that devices that emit RF energy and operate at or below 6 GHz with a separation distance of up to 20 cm (about 8.5 inches) between the user and the device.

What is SAR? Learn More With Help From RF Exposure Lab

At RF Exposure Lab, we work hard to go above and beyond and make sure that our clients understand what we do and assist them through the regulatory maze that makes up SAR testing. Through our unique expertise and commitment to our clients, we guarantee accurate SAR testing and results.

We offer SAR testing for a variety of wireless merchandise including cell phones, laptops, tablets, medical devices, survey equipment, wireless modems, and much more.

If you’re looking for SAR testing that is provided with speed, accuracy, expertise, and integrity, contact us to get a quote for our services.