SAR Testing Standards: SAR Regulation in Design

SAR Testing Standards: SAR Regulation in Design

It’s common for manufacturers to create products that are required to meet SAR testing standards without fully understand how SAR regulations impact the design of the product. This can often lead to the product failing SAR testing and requiring a redesign. This process increases the time the manufacturer will need to spend on the product which also increases the cost of manufacturing.

Here’s how SAR testing standards can affect your product designs and what can be done to avoid redesigns.

Explaining SAR Testing Standards

The first thing you need to know about SAR testing standards is that it stands for Specific Absorption Rate. SAR is the unit of measurement for the quantity of Radio Frequency (RF) that is absorbed by the body when a person uses a wireless device within 20 cm of the body. SAR testing describes both the amount of RF energy absorbed by the body from the wireless device and the rate at which it’s absorbed by the tissue exposed to it. This is because when matter is exposed to radiation, only part of the radiation is absorbed while the rest simply passes through.

SAR testing standards provide a simple and clear way to measure the RF exposure characteristics of wireless devices to guarantee that they meet the FCC’s safety guidelines. The SAR value is indicated by watts per kilogram (W/kg) or milliwatts per gram (mW/g). RF Exposure is a measure of both the electric and magnetic field strength and power density for transmitters operating at frequencies ranging from 300 kilohertz (kHz) to 100 gigahertz (GHz). 

Wireless devices are required to be evaluated to meet the RF exposure limits that have been determined by the FCC and other federal governmental agencies around the world.

What is SAR Testing?

Explaining SAR testing standards also involves explaining how SAR testing is conducted.

Using regulated models of the human head and body that are filled with liquid to mimic the way RF is absorbed by different tissues in the body, wireless devices are tested in a way that simulates the different ways users would typically hold them. In addition to this, these devices are operated at their highest power level in all the frequency bands in which they operate while they are tested. 

For example, a cell phone would be tested in multiple positions against models of the human head and body to imitate the way they are held by users, such as up to the side of the head. While placed in these different positions, a robotic probe measures the electric field at specific locations within the model head and torso. While all of this data is submitted to the FCC, only the highest SAR value for each frequency band is used in the final report to show that the device conforms to the FCC’s RF exposure guidelines.

When a device is approved by the FCC it means that the device will not expose users to levels of RF exposure higher than what is allowed by federal guidelines.

sar testing standards

SAR Testing Standards and Product Design

It’s important to take SAR testing standards into consideration even when you’re in the initial stages of designing a product. Knowing what will be required of your product from the very beginning will help you avoid unpleasant surprises when you go through the process of certifying your product. These surprises could even require a change in the design of your product, and if it’s too far along in the design process, this could be very costly.

Products are classified as either fixed, mobile, or portable depending on how they’re installed and how they’re used. 

A fixed product is a product with an antenna that is permanently affixed to a structure and can’t be easily moved. These products can require a license aside from the FCC’s Part 15 certification.

Mobile and portable products are those that can be easily moved from one place to another and may be used in close proximity to your body. The distinction between these two products is separation distance. A mobile device is used 20 cm or more from the body, while portable devices are used less than 20 cm from the body. However, devices held in your hand are still classified as portable.

How RF Exposure Lab Can Help

The bottom line is that each product you manufacture is unique and needs to be tested according to its specific requirements. Output power, antenna gain, duty cycle, and separation distance are all factors that affect testing requirements. Understanding these factors when you begin the design process will help you avoid the headache of product redesigns or an inability to pass SAR testing standards.

We go above and beyond to make sure our clients understand what we do and assist them in understanding how SAR testing standards influence the design process. Through our unique expertise and commitment to our clients, we guarantee accurate SAR testing and results.

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

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