If you’ve ever looked at electromagnetic compatibility (EMC) regulations, such as FCC Part 15, you’ve likely seen the term “radiated emissions” used frequently.
Radiated emissions are a common type of electromagnetic radiation. They can cause a variety of issues for electronic devices, including electromagnetic interference (EMI) that may prevent certain types of devices from functioning properly.
Limiting radiated emissions is a key aspect of complying with EMC regulations. As an electrical device testing lab, we often help our clients implement solutions to reduce radiated emissions in order to comply with regulations such as FCC Part 15 or European Union EMC directives.
Below, you can find more information about what radiated emissions are, what causes them to occur, and the impact they can have on electronic and electrical devices and equipment.
You can also learn more about steps that you can take to control radiated emissions from your device and comply with electromagnetic compatibility regulations.
If you need help with EMC compliance, FCC certification, or would simply like to speak with our engineering and regulatory compliance team, contact us online or call us at 866-540-5287.
What Are Radiated Emissions?
Radiated emissions are a form of electromagnetic radiation. They’re generated from electronic devices and radiate away from the device through the air, hence their name.
Devices can produce both intentional and unintentional radiated emissions. A cell phone, Wi-Fi router or radio transmitter device, for example, will generate radiated emissions deliberately to communicate or transmit information. These devices are called intentional radiators.
Other devices may produce radiated emissions unintentionally as a byproduct of their design or internal components. Devices that are not designed to produce radiated emissions, but produce them as an unwanted design issue, are called unintentional radiators.
Common examples of unintentional radiators include televisions, power supplies and electronic devices that are not designed to use radio waves for communication.
Why Do Radiated Emissions Occur?
A range of factors related to the design and components of an electronic device can contribute to radiated emissions. A device may produce radiated emissions as a result of:
- High-speed digital circuits and switching power supplies
- Wires, circuit traces and/or connector that act as antennas
- Insufficient electromagnetic shielding within a device
- Inadequate electromagnetic filtering within a device
- Other design and/or component issues
Certain factors, such as poor layout design, may not directly cause radiated emissions, but can increase the severity of radiated emissions from a device.
Radiated Emissions and Electromagnetic Interference
Radiated emissions are a common cause of electromagnetic interference. When an electronic device produces significant levels of radiated emissions, it can affect other devices in a shared environment.
This may cause:
- Noise and static on radio receivers that affect communications, including emergency communications systems.
- Wi-Fi connectivity issues, including dropped connections, slower data transfer rates, reduced range and interruptions.
- Changes in Bluetooth connectivity, such as signal disruptions and loss of connection between devices.
- Static noise and degraded sound quality in speakers, microphones, headphones and other audio devices.
- Visual noise that affects televisions and other displays, including flickering and visible lines on TVs and monitors.
- Inaccurate measurements and/or improper functioning, including in medical devices, industrial equipment and safety systems.
- Data corruption and/or data loss in computer systems.
Radiated Emissions and FCC Part 15
Radiated emissions can pose a significant risk both to the operations of consumer devices and to health and safety. In a medical environment, excessive radiated emissions may stop devices from producing accurate measurements, preventing diagnosis and treatment.
In an industrial environment, interference caused by emissions can potentially affect automated systems and/or heavy equipment, making the working environment less safe.
Because of these issues, the FCC closely regulated the radio frequency spectrum in the United States. Devices that produce radiated emissions are subject to FCC Part 15, which establishes minimum performance standards to limit radiated emissions from electronic devices.
Under FCC Part 15, devices may not exceed regulatory limits for radiated emissions. Our guide to FCC Part 15 Class A and Class B limits provides more information about these limits and the testing procedures for electronic devices.
Put simply, if your device can produce radiated emissions, either intentionally or unintentionally, it needs to be lab tested to verify that it operates within the FCC’s emission limits.
What Happens if a Device Exceeds the Part 15 Radiated Emissions Limits?
By law, an electronic device may not display the FCC mark unless it has completed lab testing and received equipment authorization, either via FCC certification or Supplier’s Declaration of Conformity (SDoC).
The FCC conducts market surveillance and has a long history of applying fines and other legal penalties to manufacturers and distributors or non-compliant devices.
Furthermore, many distributors, such as Amazon, require that radio frequency devices have an FCC ID in order to go on sale in their marketplace.
If your device displays the FCC mark without complying with Part 15 emissions limits, or enters the market without proper FCC equipment authorization, you could potentially face legal action from the FCC.
How to Reduce Radiated Emissions
Managing your device’s radiated emissions is a critical aspect of FCC compliance. Your device will need to demonstrate that it operates within the FCC’s requirements to receive authorization and legally go on the market in the United States.
A variety of approaches can be used to reduce radiated emissions from your device, including:
- PCB design and layout techniques.
- Use of electromagnetic shielding and/or filtering.
- Grounding techniques.
Our guide to reducing radiated emissions provides more information about limiting emissions from your device. You can also contact us online to talk with our engineers about methods for reducing electromagnetic radiation.
