What Is EMI Shielding and How Should You Use It?

What Is EMI Shielding and How Should You Use It?

Our world is continuously humming with electromagnetic interference in the twenty-first century (EMI). These electromagnetic disruptions are caused by the millions upon millions of electronics and appliances we use every day, as well as some natural events. Although humans cannot detect this interference, many critical electrical and electronic devices can.

When a machine encounters too much interference, it can cause major performance and reliability issues. As a result, most device makers incorporate EMI reduction or elimination mechanisms into their products. These EMI shielding systems use a number of techniques to protect our most critical electronics from interference.

If you design, manufacture, or utilize EMI-sensitive products, you should have a fundamental understanding of how this phenomenon works and how to mitigate it. This article will discuss the underlying principles of EMI as well as the most frequent types of interference. Then, we will have a look at some of the Polycase enclosures with built-in EMI shielding for sensitive equipment.

What Exactly Is EMI?

EMI is described as the transfer of undesired electromagnetic radiation to an electrical or electronic device. These impulses can disrupt a device’s operation and cause substantial damage. EMI can come from a variety of sources, both natural and man-made. The most common sources of EMI are typical household and office gadgets. Some devices, including as television remote controllers, generate modest and weak fields. Others, like as microwave ovens and smartphones, produce more potent ones. When these fields interact with other devices, they might cause harmful interference.

Furthermore, EMI does not have to come from somewhere else. Another prominent source of difficulties is internal EMI, which occurs when one of a device’s components generates interference in another component. Upstream issues with the quality and conditioning of power sources are also common offenders, and the combination of these two types of internal EMI can cause major troubles for device designers and builders.

As if such sources were not enough to cause difficulties, nature itself can produce EMI. Thunderstorms and solar storms are natural emitters of electromagnetic radiation, and they can have similar negative effects on electrical systems. You may also hear about radio frequency interference (RFI) in conversations about EMI, as the two phrases are frequently used together, if not interchangeably. RFI is a subset of EMI that occurs in the radio frequency (RF) region of the electromagnetic spectrum. Because so many devices, including many common forms of power switching equipment and electric motors, can emit frequencies in this range, it is an exceptionally prevalent sort of interference.

What You Should Know About EMI Shielding

EMI is a complex phenomenon that can interact unexpectedly with a variety of devices, materials, and circuit routes. The following are some of the most essential EMI and RFI shielding facts:

  • Some devices, such as Wi-Fi routers and key fobs, require the capacity to transmit RF signals wirelessly. Metal enclosures and other EMI-blocking enclosures can also interfere with the transmission on which these devices rely. Polycarbonate enclosures are frequently a superior alternative for these applications.
  • Seams or gaps that have not been adequately fastened can undermine an enclosure’s shielding Even small openings in the enclosure can operate as antennas, allowing EM radiation to exit or enter. To address this, enclosure designers will frequently specify enclosures with continuous body designs that allow just a small quantity of EM radiation to escape.
  • Grounds are frequently a source of persistent EMI because the frequencies in a high-impedance ground can generate a so-called “noise voltage” that is difficult to remove. Ground EMI is often best controlled by using low-impedance grounding procedures.