Anechoic Chambers
Shielded Chambers,
Screened Rooms
& Faraday Cages
Anechoic Absorbers
Shielding materials & shielding components

The facts about Electromagnetic Shielding

Electromagnetic Shielding
Download pdf version of this page Electromagnetic Shielding
Global EMC... Electromagnetic Shielding
The Global EMC ‘pan’ shielding system is fabricated from 2mm thick galvanized steel. The modular panels are bolted together using special
Visit out sister website and read more.

The shielding of electromagnetic energy applies to:


  1. Radio wave
  2. Microwave
  3. Magnetic energy

The function of shielding is to prevent radiated electromagnetic energy going into or out of a shielded chamber (Faraday cage).


The function of shielding is called signal loss and is tested by transmitting a known field strength one side of the shield wall and detecting any remaining signals at the other side of the shield wall.


Shielding performance is expressed in dBs where:

  • -40dB = 1:100 ratio of reduction in field strength
  • -60dB = 1:1000 ratio of reduction in field strength
  • -80dB = 1:10,000 ratio of reduction in field strength
  • -100dB = 1:100,000 ratio of reduction in field strength

The reduction of the field strength is known as attenuation (to attenuate)



The shielding methods can be:


  1. Modular steel panel (single skin), this is widely known as the PAN system
  2. Wooden core, with thin steel covering, this is widely known as the ‘Sandwich system’
  3. Welded seam chambers
  4. Foil/conductive material chambers

The PAN system

This system is single 2mm skin with the edge flanges and a double bead wire gasket crushed with use of nut/bolts


This is the most common system in use today. The PAN system is high performance at low frequencies and high microwave frequencies.


The PAN system is durable and can easily be re-sited although dimensional modifications require factory made panels.


Achievable performance is >-100dB @ 100KHz to 40GHz depending on the manufacturer


The Sandwich system

This system uses clamp to together strips onto steel clad wooden core boards


This system is widely used and is also good in shielding performance, although perhaps not as good as the PAN system in high microwave due to this system not employing linear gaskets.


The Sandwich system is versatile and can be site modified and easily re-sited.


Achievable performance >-100dB from 100KHz to 10GHz depending on the manufacturer.


Welded chambers

This system is not common and is for special applications, very low frequency magnetic shielding (50/60Hz magnetic field) is achieved by this shielding method.


Some military chambers use welded cages for enhanced NEMP (Nuclear Electromagnetic Pulse) shielding.


Foil chambers and conductive material tent chambers

These chamber types are relatively low in performance but are used in special applications.


The foil chambers can be used in medical applications.


The shielded tents are used where re-site and mobility are an issue but the performance is limited to -50~55dB


Shield testing

The test should be done by an independent competent test body so as to have validity. Shielding test standards are:


MIL STD 285 obsolete but still widely referred to
EN50147-1 Euro-norm
IEE299