Electromagnetic shielding is a barrier that covers electronics to prevent EMI. It is also known as radiation shielding. Often, EMI shielding is used as the umbrella term to encompass all types of EMI. RF shielding and magnetic shielding are two subtypes of EMI shielding. RF shielding is used to block video frequency electromagnetic radiation. Shields that are effective at blocking RF waves and other types of waves are sometimes called EMF Shields.
On the other hand, magnetic shielding is different as you cannot block a magnetic field the same way the electromagnetic energy is blocked. This is because magnet field lines run from its north pole to the south pole and monopole magnets do not exist. Hence, you have to redirect the magnetic field lines. This is achieved by separating two magnets with a magnetic barrier. During the process, the magnetic field lines of the magnet interact with the barrier which causes both magnets to bounce back before reaching the magnet on the other side. Since the magnetic lines of the magnets are not able to interact, their impact on each other is decreased or nullified.
Today’s technology requires magnets to work. Like EMI, you must prevent magnetic interference; otherwise it can impede the operation of other magnetic devices. Some Shields combine conductive and magnetic mediums which prevent interference from both EMI and magnetism.
In today’s world, we are surrounded by a lot of electronic devices. It’s like we are in the age of science fiction. Due to many electronic devices, each one can interfere with another if it is not properly shielded.
The electromagnetic shield has a two-fold goal. It provides isolation to the energy of the device so it doesn’t affect anything else. On the other hand, it also blocks the external energy from getting in. If the devices do not have shielding, electronics wouldn’t function as designed or will stop functioning altogether. EMI shielding is important because of the following reasons.
- Brownouts and blackouts
Brownouts are any type of partial service outage, whereas, a blackout is a full outage. Brownouts and blackouts are not limited to power outages.
- Electrical fast transitions or EFTs
When there is a power outage and a transfer sequence is in place. You may start receiving power from a generator. When this happens, it is known as EFT. With the help of EMI, you can experience unwanted EFTs.
- Static on phone lines
If you remove the plastic jacket from a phone line you will see another layer covering the wires. The second layer that you will see is generally on metallic foil or a metallic plaited braid which protects the lines against EMI. It is a type of RF shielding which helps in reducing static during phone calls.
- Power faults
A power fault occurs due to any abnormality in an electrical current. One of the excellent examples of a power fault is a short circuit; however, it is not the only kind. Power faults are sometimes caused by an EMI.
