What Is a Faraday Cage & How Does It Work?

Any electronic device can be affected by electromagnetic interference (EMI). Most devices have built-in EMI shielding to minimize the effects of these disturbances. For example, smartphones and tablets have shielding to protect chips and interfaces for cellular, Wi-Fi, and other radio frequency signals.

However, such internal shielding isn’t foolproof, and highly sensitive equipment may need further protection when there’s a significant source of EMI. For example, electrical cords are very efficient at transferring EMI into the surrounding environment and can cause network performance problems and other issues if not properly managed.

What Is a Faraday Cage?

Electronic devices can be protected from EMI using a Faraday cage — an enclosure that uses a conductive material to attenuate undesirable electromagnetic frequencies. Microwave ovens are commonplace examples of Faraday cages. The shielding on network cables is also based on Faraday cage principles.

History of the Faraday Cage

The Faraday cage was invented in 1836 by English scientist Michael Faraday, who discovered that an electrical conductor could be used to block electromagnetic fields. He observed that a charge was present only on the conductor’s surface and did not affect its interior.

He demonstrated the effect by building a room shrouded in metal foil and bombarding it with high-voltage electrostatic discharges. An electroscope inside the room showed that no electric charge was present. The charge remained on the foil’s surface and never penetrated the shielding to enter the room.

What Is a Faraday Cage Used For?

Faraday cages have several applications in IT. They can shield sensitive equipment from electrical disturbances and prevent side-channel attacks in which hackers intercept and analyze electromagnetic emissions. They are also used to minimize radio frequency (RF) interference when testing electronic devices.

How to Construct a Faraday Cage

You can buy EMI shielding materials online to construct a Faraday cage, but there are several factors to consider.

Faraday Cage Materials

A variety of materials can be used, including copper, aluminum, and steel. However, the effectiveness of the shielding depends upon the electrical conductivity and magnetic properties of the material. For example, copper is expensive but doesn’t need to be as thick as other materials to attenuate RF signals.

Application Considerations

If a wide range of electromagnetic interference must be blocked, the enclosure may need to be wrapped in multiple layers of conductive material. Any holes in the enclosure must be significantly smaller than the wavelength of the radiation.

You can also buy ready-made Faraday cages, including bags and pouches for smartphones, tablets and laptops, and enclosures for wireless routers. However, such consumer-grade products have little to no value in the enterprise IT environment.

Faraday Cages in the Data Center

Shielded cabinets provide the best protection against EMI in the data center. Historically, shielded cabinets were primarily used as a cybersecurity countermeasure against power analysis and EMI side-channel attacks. The proliferation of Wi-Fi, Bluetooth, and other wireless technologies pose additional eavesdropping threats, increasing the need for Faraday cages that attenuate a wide range of radio frequencies.

Real device testing is another significant use case of shielded cabinets. Organizations that need to test applications on smartphones, tablets, IoT devices, and other hardware need a means of attenuating RF interference. A rack-level Faraday cage is the ideal solution.

DefenseShield RF Shielded Cabinet from Enconnex

Enconnex developed the DefenseShield RF Shielded cabinet to protect against EMI at the rack level. Purpose-built to provide 85dB of attenuation at frequencies ranging from 1MHz to 10GHz. DefenseShield has been tested, approved, and implemented by government agencies, internationally accredited labs, and communications companies.

The 42U (customizable) cabinet has a standard footprint that readily integrates into any data center environment. At just 375 pounds, it can be installed virtually anywhere without the need to reinforce the floor.

DefenseShield can support up to 400 devices for high-density real device testing. Ten integrated fans provide 235 CFM of airflow each to minimize the risk of a thermal event.

A Faraday cage is an age-old solution to the problem of electromagnetic interference. Contact Enconnex to learn how the DefenseShield RF shielded cabinet provides security and RF attenuation for today’s IT environment.