Attention Deficit Disorder Prosthetic Memory Program

Faraday Cage

ADDPMP134

A Faraday cage or Faraday shield is an enclosure used to block electromagnetic fields. A Faraday shield may be formed by a continuous covering of conductive material, or in the case of a Faraday cage, by a mesh of such materials. Faraday cages are named after scientist Michael Faraday, who invented them in 1836.

A Faraday cage operates because an external electrical field causes the electric charges within the cage’s conducting material to be distributed so that they cancel the field’s effect in the cage’s interior. This phenomenon is used to protect sensitive electronic equipment (for example RF receivers) from external radio frequency interference (RFI) often during testing or alignment of the device. Faraday cages are also used to enclose devices that produce RFI, such as radio transmitters, to prevent their radio waves from interfering with nearby sensitive equipment. They are also used to protect people and equipment against actual electric currents such as lightning strikes and electrostatic discharges, since the enclosing cage conducts current around the outside of the enclosed space and none passes through the interior.

Faraday cages cannot block stable or slowly varying magnetic fields, such as the Earth’s magnetic field (a compass will still work inside). To a large degree, though, they shield the interior from external electromagnetic radiation if the conductor is thick enough and any holes are significantly smaller than the wavelength of the radiation. For example, certain computer forensic test procedures of electronic systems that require an environment free of electromagnetic interference can be carried out within a screened room. These rooms are spaces that are completely enclosed by one or more layers of a fine metal mesh or perforated sheet metal. The metal layers are grounded to dissipate any electric currents generated from external or internal electromagnetic fields, and thus they block a large amount of the electromagnetic interference. See also electromagnetic shielding. They provide less attenuation of outgoing transmissions than incoming: they can block EMP waves from natural phenomena very effectively, but a tracking device, especially in upper frequencies, may be able to penetrate from within the cage (e.g., some cell phones operate at various radio frequencies so while one cell phone may not work, another one will).

The reception or transmission of radio waves, a form of electromagnetic radiation, to or from an antenna within a Faraday cage is heavily attenuated or blocked by the cage; however, a Faraday cage has varied attenuation depending on wave form, frequency or distance from receiver/transmitter, and receiver/transmitter power. Near-field high-powered frequency transmissions like HF RFID are more likely to penetrate. Solid cages generally attenuate fields over a broader range of frequencies than mesh cages.

Faraday Cage - © Attention Deficit Disorder Prosthetic Memory Program
Hydra-Shok - © Attention Deficit Disorder Prosthetic Memory Program
ADDPMP142
Hydra-Shok
Offshore Architecture - © Attention Deficit Disorder Prosthetic Memory Program
ADDPMP423
Offshore Architecture
United States Bullion Depository - © Attention Deficit Disorder Prosthetic Memory Program
ADDPMP217
United States Bullion Depository
Animals by Number of Neurons - © Attention Deficit Disorder Prosthetic Memory Program
ADDPMP573
Animals by Number of Neurons
Doin Time in Times Square - © Attention Deficit Disorder Prosthetic Memory Program
ADDPMP184
Doin Time in Times Square
Eye Tracking - © Attention Deficit Disorder Prosthetic Memory Program
ADDPMP125
Eye Tracking
Inferno Planet Wasp-76b - © Attention Deficit Disorder Prosthetic Memory Program
ADDPMP157
Inferno Planet Wasp-76b
Project Grizzly - © Attention Deficit Disorder Prosthetic Memory Program
ADDPMP141
Project Grizzly
Ricardo López - © Attention Deficit Disorder Prosthetic Memory Program
ADDPMP355
Ricardo López
Sam Little Portraits - © Attention Deficit Disorder Prosthetic Memory Program
ADDPMP094
Sam Little Portraits
The Raven Paradox - © Attention Deficit Disorder Prosthetic Memory Program
ADDPMP353
The Raven Paradox
Magnus Hirschfeld - © Attention Deficit Disorder Prosthetic Memory Program
ADDPMP016
Magnus Hirschfeld

You are using an outdated browser.
Please upgrade your browser to improve your experience.