EMI Protection: 3 of the Most Common Myths


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When radios first made their debut, noise interruptions—from pops and bangs to more subtle disruptions—were all chalked up to being part of the listening experience. But as electronic systems began to appear in military applications, the impact of electrical interference on the operation of equipment and the potential to set off false triggers evolved into a larger issue.

As this realization has grown, so has the need for greater electromagnetic interference (EMI) protection. While strides have been made in the testing and optimization of electronic systems, there is still quite a bit of confusion surrounding this complex topic.

We’re here to help address some common EMI protection myths.

3 Myths About EMI Protection

“My device is working fine so electromagnetic interference isn’t an issue.”

There are plenty of cases where electromagnetic interference takes shape in the form of sounds. You can find it in a car radio that buzzes as you drive beneath a power line or the distortion of television audio when lightning strikes.

Not every disruption, though, manifests in this way. A device can continue to operate as it should without interruption, but that doesn’t stop other systems from accessing its private data.

A good example of this is intentional electromagnetic interference (IEMI). These attacks typically involve sharp, high-voltage pulses that disable electronic systems for a short period and are nearly undetectable. This masks the breach of the system and thus the full scope of the threat to electronic devices’ EMI protection.

“All sources of electromagnetic interference are obvious.”

Frequent flyers are familiar with switching mobile devices into Airplane mode. This setting turns off cellular, Wi-Fi, Bluetooth and data connections that can hamper the function of sensors and equipment on commercial airplanes.

Smartphones and cell phones are clear sources of electromagnetic interference in this scenario. Yet there are many other cases where the sources of EMI are less than obvious.

The IEMI highlighted above is one example that falls under this umbrella, but there are also many others to add to the list. Consider biological elements like myopotentials—the electrical signals that arise from muscle—and temperature extremes. When sensed by medical devices such as pacemakers, these elements can negatively impact the functionality of the device.

“Putting equipment in an all-metal enclosure will adhere to EMI requirements.”

Shielded enclosures are recognized as a valid solution for EMI protection. But with a lack of attention paid to seams and openings in the enclosure design, noise currents created within the walls of the enclosure can flow out of the system, resulting in radiated emissions as well as failures in immunity and susceptibility.

The key to preventing this issue is limiting the size of these elements. Further, it’s recommended that openings approaching the half-wavelength of a problem frequency are avoided to ensure effectiveness.

What’s also important to remember is that the frequency of maximum radiation can change when shifting from an unshielded to a shielded enclosure. Because of this, special attention must be paid to avoiding or limiting the magnitude of signal current returns—an element that can be attributed back to the properties of gaps between fasteners.

Consult with Switzer for Your EMI Shielding Needs

The increased use of electronic devices has created more opportunities for EMI issues. That’s why EMI protection has become all the more important.

At Switzer, we recognize the value of EMI protection and work to design and manufacture effective shields that meet this need. To learn more about how we can help with your design, connect with one of our team members today.



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