EMC: Electro-Magnetic Compatibility

Once described as “the study of all the components that the designer neglected to put on the schematic” and sometimes referred to as a black art, EMC has a bit of a bad reputation. It doesn’t have to be scary as Unit 3 Compliance can help you navigate your way through this complex world.

Essentially it describes the performance of a piece of equipment within the electromagnetic environment. All electronic and electrical equipment must conform to various national laws and regulations detailing how it should behave within this environment. Compliance with these laws and ordinances is a fundamental requirement of being able to sell your product to your customers.

EMC is generally split into two aspects, those of emissions and immunity


diagram showing difference between emissions and immunity


This deals with the levels of radio interference emitted by the equipment under test. This could be radiated as electromagnetic radio waves in free space or conducted on the cables and interfaces of the product.

This energy could interfere with existing radio services such as broadcast TV, emergency services radio, mobile phones, etc.


It is generally expected that exposing the equipment under test to various natural or man made EM phenomena will result in the product being unaffected.

This interference could take the form of static discharge from walking across a synthetic carpet through to a nearby lightning strike, from welding or arc discharge through to leaving a mobile phone close by.


Ask us about EMC testing for your products