Skip to main content

How to Stop Radio Frequency Interference

Published Date
Author Cadence PCB Solutions

Key Takeaways

  • RF interference is the effect of unwanted RF energy in the system under consideration, which manifests as degraded performance, loss of data, and equipment damage.

  • RFI can be detected using spectrum analyzers.

  • The most practical RFI suppression technique is achieved by installing filtering circuits across the noise-producing terminals of electronic devices.

 Electromagnetic spectrum

The electromagnetic spectrum that ranges from 3 kHz up to 300 GHz is referred to as radio frequencies 

The electromagnetic spectrum that ranges from 3 kHz up to 300 GHz is referred to as radio frequencies. It is a limited resource, and numerous electronic and wireless systems utilize this spectrum for various applications and services. With the proliferation of systems using the radio spectrum, the stability and performance of electronic devices utilizing this spectrum have deteriorated. This deterioration can often be attributed to radio frequency interference. So, how to stop radio frequency interference? In this article, we will discuss RF interference as well as its causes, detection, and suppression methods. 

Radio Frequency Interference 

Undesired electromagnetic energy influencing the functioning of electronic systems is called interference. Interferences are generally categorized as electromagnetic interference (EMI) and radio frequency interference (RFI). RF interference is narrowband interference that affects the electronic system and is considered a subsystem of EMI.

RF interference is the effect of unwanted RF energy in the system under consideration, which manifests as degraded performance, loss of data, and equipment damage. In electronic systems infected by RF interference, the RF source and receiver are physically separated, yet unwanted electromagnetic signals producing interference affect the proper functioning of the device. The electromagnetic noises get inductively coupled between the source and receiver and are called radiated emissions. 

The Causes of RF Interference 

The extensive use of consumer electronics increases the amount of RFI in the air. The air as a medium of electromagnetic radiation is crowded by RF interference signals, which disturbs the functioning of electronic devices. 

Electronic manufacturers must pay attention to RFI in every stage of design and development. The electromagnetic compatibility of electronic devices confirms the device under consideration is producing acceptable levels of RFI. To confirm this, EMC testing is conducted. 

Other causes of RFI are:

  • The proliferation of electronic devices utilizing the same radio frequencies or same range of radio frequency spectrum.

  • Congested circuit connections of electronic devices.

  • Design flaws in electronic circuits.

  • Poorly designed enclosures of electronic devices with low absorption loss. 

Detecting  Radio Frequency Interference

RF interference must be detected during each stage of electronic product development. RFI can be detected using spectrum analyzers. Swept-tuned spectrum analyzers are utilized for RFI detection. They display measurements by sweeping continuously across a given frequency range. The swept-tuned analyzers sweep from lowest to highest frequency. Real-time spectrum analyzers don’t have as many limitations as swept-tuned spectrum analyzers, as they continuously capture the spectrum information for any span.

Once RFI is detected, it is critical to reduce the radio frequency interference to ensure better performance, service life, and reliability. The upcoming section discusses how to stop radio frequency interference. 

How to Stop Radio Frequency Interference 

There are three basic methods available to stop radio frequency interference in electronic circuits. 

  1. Shielding

Enclosing the electronic system in a metal can help to contain RF noise and prevent RF interference from reaching the antenna. In practical cases, there is some radio noise leakage. However, RFI is considerably reduced by shielding. The shielding effectiveness increases if the metal enclosure is electrically bonded to the ground. Wiring through the shield can behave as an antenna, so avoid having wires pass through the shield.

  1. Filtering

This method is the most practical RFI suppression technique. It is achieved by installing filtering circuits across the noise-producing terminals of electronic devices. Capacitors and choke coils (or a combination of them) are the electrical components that provide effective filtering. 

  1. Grounding

Proper grounding ensures that RF noise is conducted away to the ground instead of being emitted as radiation.

Shielding, filtering, and grounding are the immediate answers to the question of how to stop radio frequency interference in electronic circuits. Cadence software can assist you in planning an appropriate RF interference suppression method suitable for the circuit or device of interest. 

Subscribe to our newsletter for the latest updates. If you’re looking to learn more about how Cadence has the solution for you, talk to our team of experts.