Understanding EMI and EMI Shielding

EMI also called electromagnetic interference or RFI ( radio frequency interference) is the unwanted electromagnetic force to an electrical appliance. EMI occurs when one device or source disrupts the signal of another. We humans can’t see it with naked eyes but the vast amount of devices and electronics that we use can feel it. All of these devices cause these electronic disturbances. These electromagnetic interference can interfere with your devices signals and can cause problems in its performance or more serious harm. The EMI is caused by both natural sources like solar flares or lightning and man made things like old devices whose shielding is damaged or doesn’t exist. If EMI shielding didn’t exist you wouldn’t be able to answer your phone without the signal crossing over. 

There are two types of electromagnetic interference that exist. Firstly, the narrow band EMI as the name suggests works in a narrow spectrum like television or radio or your phone and is less harmful. It might cause some disruptions in the performance of the device but could be fixed easily. Another is Broadband EMI, which occupies a large part of the EM spectrum. This can cause a lot of damage to the device even in its overall breakdown.

To avoid all the above mentioned problems EMI shielding plays an important role. The main purpose of an EMI shielding is to protect sensitive devices. EMI shielding is a technique used in electronic devices that creates a barrier between two electromagnetic signals which protects signals from being disrupted from external electromagnetic signals or prevents the leaking of strong electromagnetic signals that would interfere with surrounding signals. Common methods of EMI shielding include use of Aluminium or steel electrical enclosure boxes for natural EMI protection. An EMI shielded gasket in an electronic enclosure can be an effective way to control EMI.  Conductive spray coating or using EMI shielded cables can further reduce EMI. EMI mitigation techniques like placing a wall between two devices or adding electronic filter circuits to a device can help reduce EMI too. A metallic screen called the Faraday cage is used to either completely surround the receiving device or the transmitting device.

Important things to keep in mind about EMI shielding is that any small gaps or vacancy could lead to EMI leakage. This disrupts the working of the EMI shielding. All the wireless devices such as your wi-fi could face problems due to metal enclosures as they need to transit RF signals wirelessly.  Try using low impedance grounding techniques as the grounds are a great source of EMI persistence. EMI shielding could be found in medical equipment like AM/FM emergency service transmission.  Any data stored on an RFID chip is protected by EMI shielding. Other uses are in the aerospace industry, military, mass transit systems etc.

In conclusion, if the electromagnetic radiation were visible to naked eyes, there wouldn’t be any empty space left in your house to walk. Without proper EMI shielding, it could lead to a complete failure in your device.

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