What is Radiated Emission test?

Radiated Emission is only one of the Electromagnetic Compatibility (EMC) tests. It is a test that must be performed in an anechoic chamber  or Open Area Test Site (OATS) after the EMC standard has been determined. This standard has to be determined according to the product. Radiated Emission testing is to determine whether the intended product is below a certain level of unwanted electromagnetic frequencies. If the measurement results of a product is under the limit value stated on the standard, this test is counted as PASS. If measurements exceed the limit, it is necessary to make improvements on the product in terms of design change or EMC. The work done on this kind of product is R & D work and it is very essential for manufacturers.

The measurement frequency range of Radiated Emission tests usually starts from 30 MHz and can be up to 1 GHz, 2 GHz or 6 GHz depending on the product specification and the standard applied. Measurements are made via antennas designed for specified frequencies and measuring devices called EMI Receivers. The measurement distance between the product and the antenna is typically 3 meters or 10 meters. It is also possible to change the limits according to the measurement distance. For instance, a limit value of 40 dBuV/m at 3 meters can be reduced to 30 dBuV/m at 10 meters.

Radiated Emission test is one of the most basic tests of EMC tests and is a test that the product designers need to be aware of. Precautions related to the EMC testing of a product must be initiated at the design stage of the product and should continue during the serial production phase. Even when the product is at the end user, precautions should be followed.