EMI Shielding

EMI shielding can be very important in electronics work. EMI stands for Electro Magnetic Interference but it is also called EMI, radio frequency interference, or RFI.

In general, this is an unwanted disturbance caused in a radio receiver or other electrical circuit by electromagnetic radiation emitted from an external source; EMI shielding attempts to block that disturbance so that the circuits will not be affected by it.

It should be noted that these disturbances can be minor or they can be major in strength. The disturbance may interrupt, obstruct, or otherwise degrade or limit the effective performance of the circuit depending on how strong it is and the level of EMI shielding that is in place.

The disturbance source may be any object, artificial or natural, that carries rapidly changing electrical currents, such as an electrical circuit, the Sun, overhead power lines, the Northern Lights, or many other objects.

It is interesting to note that EMI can be produced deliberately or intentionally, as in some forms of electronic warfare which we often refer to as "jamming". It can also be produced unintentionally. An example of this might be the interference you hear on AM radio while in urban areas. Without the proper EMI shielding, it can also affect FM radio and television reception, although this is usually to a lesser degree.

There are many ways to prevent EMI without having to resort to EMI shielding. When these internal methods do not work, however, EMI shielding is required.

EMI shielding can be accomplished using such things as RF gaskets and copper tape. Most digital equipment is designed with metal or conductive-coated plastic cases which is also very helpful in EMI shielding.

EMI shielding is usually a last resort after other techniques have failed because of the added expense of RF gaskets and the like.

You should know that most countries and many municipalities within those countries have legal requirements that mandate electromagnetic compatibility. What this means is that electronic and electrical hardware must still work correctly when subjected to certain amounts of EMI, and they should not emit EMI which could interfere with other equipment such as radios or televisions and the like. If they do, EMI shielding is required for the device so as to reduce or eliminate the disturbance that others might experience from your equipment.

You can learn more about EMI shielding and how to accomplish it by doing an online search. You will need to be careful to ensure that the procedures you use will realistically work on your particular project.