What Is RF Interference, What Causes It, & How To Block It

Many devices emit radio frequency (RF) radiation, including mobile devices, Wi-Fi networks, remote controls, cordless phones, Bluetooth headsets, and radio and TV broadcasts. Microwave ovens and fluorescent lights are other common sources of RF radiation. 

What Is an RF Signal?

The term “radio frequency” refers to a subset of the electromagnetic spectrum from around 9 kHz to around 300 GHz. 

Radio Frequency Range

The radio frequency ranges include:

• Very low frequency (VLF) — 9 kHz to 30 kHz
• Low frequency (LF) — 30 kHz to 300 kHz
• Medium frequency (MF) — 300 kHz to 3 MHz
• High frequency (HF) — 3 MHz to 30 MHz
• Very high frequency (VHF) — 30 MHz to 300 MHz
• Ultrahigh frequency (UHF) — 300 MHz to 3 GHz
• Super-high frequency (SHF) — 3 GHz to 30 GHz
• Extremely high frequency (EHF) — 30 GHz to 300 GHz

What Is RF Interference?

RF interference occurs when RF radiation disrupts the normal functions of an electronic device or network. It can also be caused by conduction through a power cord. Cables can be both a source and receiver of RF interference, conducting or radiating RF signals or picking up RF signals from other sources.

What Are the Causes and Problems of RF Interference?

RF interference is hardly a new phenomenon. Anyone who’s heard parts of two radio broadcasts simultaneously has experienced the overlap of radio station signals.

What Provides the Greatest Source of RF Interference?

However, wireless networks are a leading source of RF interference today. As more devices connect to a network, the RF spectrum can become so crowded that frequency bands overlap. Other wireless devices that use the same 2.4 GHz frequency as Wi-Fi can also interfere with network connectivity, as can nearby microwaves and other types of equipment. 

RF interference can have critical consequences for IT equipment and networks. Although Wi-Fi devices are designed to accommodate some degree of interference, they will wait for interference to die down before sending data packets. The result is dropped connections and degraded performance.

The problem can be acute for organizations that must test operating systems, firmware and applications across a multitude of devices. Many devices use wireless connectivity for communication. Real device testing requires the segregation of the equipment to prevent wireless signals from propagating.

How to Block RF Interference

For mobile applications, the number of devices required for testing is very high (hundreds or thousands), making it impossible to maintain adequate distance between them. The only remedy is to shield the equipment. Three materials are commonly used for RF shielding.

Copper

Copper is highly effective at attenuating RF signals because of its high conductivity. It can easily be formed into almost any shape and is naturally resistant to corrosion. Although expensive, it is considered the best RF shielding material.

Aluminum

Aluminum is only about 60 percent as conductive as copper but still provides an effective RF shield at frequencies above 30 MHz. It is also highly malleable and less expensive than copper. However, aluminum is subject to corrosion.

Steel

Steel provides effective shielding across a wide frequency range. It is manufactured in various forms (hot- and cold-rolled, galvanized, annealed, etc.) that affect its conductive properties. Steel may be plated with tin to protect against corrosion. 

Manufacturing an RF Shielded Enclosure

When choosing RF shielding materials, several factors will come into play, including the frequencies to be attenuated, the environment (related to corrosion), and the size and shape of the enclosure. For example, cables are typically shielded with thin aluminum foil or braided copper wires. Individual devices can be placed inside shielded enclosures, but this is too inefficient for real device testing at scale. A better approach is to utilize shielded cabinets. 

The RF-shielded enclosures on the market vary widely in their features and capabilities. Some use metal plating, making them difficult to install and move due to their weight. Others are designed for industrial use and provide only minimal electromagnetic attenuation.

When used for real device testing, the enclosure must have a means of dissipating the heat generated by IT equipment. Ideally, it will have a footprint that allows it to be integrated into the testing environment. Flexible options for shelving, power, and connectivity increase the cabinet’s functionality. Of course, an enclosure is more than a Faraday cage — you need to get power, cooling, and network connectivity into the cabinet. Every opening must be shielded to limit RF signal leakage and outside interference.

Enconnex RF Shielded Cabinets

Enconnex DevShield cabinets are shielded to effectively attenuate RF signals from 1 MHz to 10 GHz. Designed for real device testing at scale, DevShield cabinets are made of aerospace-grade aluminum with copper-nickel gaskets sealing every opening. They ensure maximum signal integrity within the cabinet and can also be configured to prevent channel interference from within. 

Enconnex DevShield cabinets are lightweight and have a standard footprint, simplifying integration into the testing environment or data center. Each unit can be customized to your specifications, making accessing and managing devices in the lab environment easy. DevShield has ten powerful fans, each providing 235 CFM of airflow to keep equipment cool. 

Our DefenseShield product offers the same protection as DevShield, but was engineered for cybersecurity and defense purposes. Both cabinets meet the following standards: UL 2416 (NWIN) Listed, MIL-STD-461, IEEE-299, NSA 94-106, MIL-STD-285, TEMPEST.

RF interference is a growing problem due to the proliferation of devices competing for the same airspace. Enconnex DevShield and DefenseShield cabinets protect against RF interference with a flexible, scalable solution that fits any data center or lab environment.

Get in touch to learn more about our shielded solutions.