PowerbyProxi > EMF

Do EMC radiation standards comprehensively cover wireless charging solutions?

August 1, 2012 / 2 Comments / 209 / Technical

EMC radiation standards are used to qualify electronic devices against interference with other electronic devices. A piece of wire that has a current running through it will generate electric and magnetic fields – “H-field” emissions measure the magnetic component and “E-fields” emissions measure the electric component. EMC radiation standards ensure that these fields do not interact with other electronic devices to impair their operation.

EMC radiation standards were really designed to control and limit the amount of interference in long distance radio communication. The current standards regulating EMC radiation have been great at regulating these devices, however you now have a new type of electronic device that intentionally generates magnetic fields – those that use wireless power. Such electronic devices were never foreseen when these standards were written.

Consequently, there is one potential aspect of wireless power solutions (read more about wireless power here) which is not currently being regulated. This is the amount of electromotive force (EMF) that can be generated in a device which is in very close proximity. EMF is basically a fancy term for voltage! Electronics are sensitive to over-voltage (some more than others) and over-voltage can cause permanent damage to devices.

Sure there is a limit on how much “H-field” you can emit however these fields are typically measured using an antenna at a few meters or feet away from a device under test. The reading from the antenna and compliance to limits will not really tell you whether your shiny new smart-phone placed on your laptop’s wireless power supply is going to fail.

But hey at least your wireless power supply doesn’t mess with your FM radio…

Kunal Bhargava is Engineering Manager for PowerbyProxi

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