Electromagnetic interference (EMI), also called radio-frequency interference (RFI) when in the radio frequency spectrum, is a disturbance generated by an external source that affects an electrical circuit by electromagnetic induction, electrostatic coupling, or conduction.
On the other hand, electromagnetic compatibility (EMC) is to ensure that a variety of different items of electronics equipment can operate in close proximity without causing any undue interference.
EMI can impact mobile phones, televisions, radios and radio astronomy. Both man-made and natural sources generate changing electrical currents and voltages that can cause EMI. This includes:
Emissions testing requires the use of EMI measurement equipment such as receiving antennas, amplifiers and spectrum analyzers. Working together, these tools provide an accurate measurement of the amount and type of noise generated by a device.
This can be done either on an open area test site or in a shielded, anechoic (or semi-anechoic), test chamber.
Immunity (or susceptibility) testing involves determining the ability of a device to tolerate noise from external sources. In order to do this, it is necessary to have tools that can simulate and measure electromagnetic energy specific frequencies.
EMC testing equipment may be used to subject a device to electromagnetic noise at various frequencies, to simulate a power surge or to assess the effectiveness of a device’s power supply.
Ultimately, the nature of the device, its intended application and any regulatory requirements will determine which type of testing equipment is required.
The U.S. military is especially concerned with EMI when it is intentionally used in electronic warfare (EW) for radio jamming.
Want to learn more? Tonex offers several courses in EMI/EMC Training such as:
For more information, questions, comments, contact us.