types of emc testing
4 min

Understanding EMC Testing

A guide to understanding EMC Testing and its importance

Posted by: Steve O'Steen Date: 09 Feb 2023

Overcoming Common Challenges & Ensuring Compliance

As the need for testing becomes more critical in today’s world, it is important to understand the latest trends. EMC testing is a critical part of any good design and compliance cycle. I am going to cover some of the most common issues faced by engineers today when it comes to EMC (electromagnetic compatibility) testing and how we can solve them with our products.

The Need for Testing

As the number of devices connected to the Internet grows, so does the need for testing. This is especially true when it comes to testing those devices that are heavily reliant on software and communication between multiple components. This includes industrial control systems, smart home appliances, connected vehicles and more.

In recent years there has been a push by many companies to make their products “smart” by adding connectivity features such as cellular modems or Wi-Fi chipsets into them in order to enable remote monitoring as well as functionality enhancements like traffic monitoring and collision avoidance systems in cars. With these kinds of products becoming more common place it is important that they are tested thoroughly before being released onto the market in order not only ensure that they work correctly but also because they comply with all relevant legislation regarding electromagnetic compatibility.

EMI Testing

Test Environment

The test environment is the key to effective EMC testing. An ideal test environment is one that has no electromagnetic interference (EMI), electrical interference, mechanical interference, and thermal interference. To achieve this goal, you need a clean room where all of these factors are minimized.

In addition to the clean room requirements, there must also be proper grounding and shielding throughout the entire test area so that any stray currents in your system cannot be transferred into other systems or into yourself through accidental contact with exposed wires or cables like power cords. 

What is an anechoic chamber?

emc testingAn anechoic chamber is a room that is designed to shield electromagnetic waves from outside interference. They're used for a variety of purposes, but the most common use is to test electronic devices in a controlled environment without any outside electromagnetic conditions affecting the outcome of the test.

An anechoic chamber not only blocks out all outside signals, but it also produces no sound of its own. This allows you to hear exactly what your device sounds like without any background noise or interference from other devices in the room. As such, an anechoic chamber can be used for many different types of testing—from audio recording and broadcasting to radar systems and even building air conditioning units!

Conducted emissions testing

Conducted emissions testing is an EMC test which is performed on a device under test (DUT) that is placed in an anechoic chamber. The DUT will be connected to a power source of known characteristics, and the cable length between it and the antenna of interest are accurately measured so that this can be taken into consideration when calculating conducted emissions levels across the frequency spectrum. The cables connecting the DUT to its power supply or other accessories may also need to be tested for conducted emissions from those components if they are present in your particular product design.

Radiated emissions testing

Radiated emissions testing is a type of EMC testing that is used to detect emissions that are radiated away from the device under test. It can be performed in an anechoic chamber, and often requires an antenna array to be able to perform high-frequency testing. The antenna array consists of multiple antennas positioned in different directions around the device under test. In radiated emissions testing, one or more antennas are connected directly or indirectly (through an amplifier) to a spectrum analyzer so that it can measure any electromagnetic signals being radiated by the device under test.

RF immunity testing

RF immunity testing is a common method of assessing the electromagnetic compatibility of electronic devices. In this type of test, the device is exposed to radio frequency (RF) signals to determine whether it will function properly after being bombarded with electromagnetic interference. This can be done using a network analyzer or other instrumentation that simulates the various signals found in everyday life.

RF immunity testing has been used since at least the 1960s and can be performed on many different types of equipment - including computers, printers, modems and routers - to determine if they will function properly when subjected to typical EMI sources such as cell phones or microwaves. A network analyzer or signal generator may be used for these tests because they are capable of producing signals that simulate real-world scenarios like nearby cell towers or microwave ovens. The spectrum analyzer component allows you to monitor any out-of-band emissions from your DUT, which can help identify potential EMI issues that might affect its performance over time as well as identify any unintentional radiators present within your DUT itself.

You need a good test plan, the right test facility, and an experienced testing provider

To get the most out of your test, you need a good test plan that covers everything from how the tests will be conducted to what data is going to be collected and analyzed. This should include any specific requirements for each test.

The right facility is also essential. You want a facility with enough space to perform every type of test separately and have room for all your equipment as well as plenty of workspace around it.

Finally, you need a testing provider that knows what they are doing. TÜV SÜD have EMC testing facilities across the US and Canada and have dedicated EMC engineers and technicians with decades of expertise.

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The key to EMC testing is to have a good test plan, the right test facility and an experienced testing provider. Anechoic chambers can help remove any interference from the environment and RF immunity testing will make sure your device will work properly in any environment. Conducted emissions testing will make sure your product doesn't interfere with other devices nearby while radiated emissions testing makes sure that it doesn't interfere with other electronics on its own frequency band as well as surrounding frequencies as well.

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