What is an EMC Shield?

Our expertise at Wurth Electronics Midcom is in power magnetics. In this blog series, we will teach you all there is to know about EMC shields. The first thing we need to do is figure out how much we know about shields.

What is a shield? In the context of EMC, a shield is a device that contains, reflects, or absorbs a radiated electrical signal.

There are primarily two types of noise propagation - one is radiated and the other is conducted. Typically, in the world of EMI shields are better suited to fix issues associated with radiated noise. When it comes to conducted noise, they are not so effective, but there are situations in which they can alleviate coductive noise with limited success.

First, here is an overview of where shields may be best used as a function frequency bandwidths.

Differential and Common Mode Chokes

For low-frequency noise, which tends to be differential and conducted, we tend to use differential filters which are effective and inexpensive. In the mid-range we typically see coupled noise. The source of the noise could be conducted or radiated and Common Mode Chokes are the most effective solution.

Shields

Radiated noise tends to be on the higher frequency spectrum and the typical shields used to resolve radiated noise are metallic shields or ferrite shields. Differential and common filters are not very effective, but it depends on a case by case basis.

Want to learn more? Stay tuned for more posts about shields, their uses, measurements, and more.

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