The IEC 61000-4-3 is an EMC standard by the International Electrotechnical Commission on the immunity requirements of electrical and electronic equipment to radiated electromagnetic energy. It establishes test levels and the required test procedures for evaluating the immunity of electrical and electronic equipment when subjected to radiated radio-frequency electromagnetic fields.

Every type of electronic and electrical equipment emits an electromagnetic field to some degree unintentionally or intentionally. Radios, TVs, and radar transmitters emit strong electromagnetic fields which can hamper other equipment’s operation if they are in its proximity. When conductors such as cables, wires, and PCB traces are exposed to RF fields, RF currents and voltages are coupled into the conductors. These stray currents and voltages are nothing but the noise that causes errors and malfunctions in the analog or digital semiconductors.

The IEC 61000-4-3 focuses on the limits of these RF emissions of the equipment. Following is the test equipment required for the standard: The IEC 61000-4-3 focuses on the limits of these RF emissions of the equipment. Following is the test equipment required for the standard:

1. Anechoic chamber
2. EMI filters
3. RF signal generator(s) capable of covering the frequency band of interest and of being amplitude modulated by a 1 kHz sine wave with a modulation depth of 80%. They shall have manual control (e.g., frequency, amplitude, modulation index) or, in the case of RF synthesizers, they shall be programmable with frequency-dependent step sizes and dwell times.
4. The use of low-pass or band-pass filters may be necessary to avoid problems caused by harmonics.
5. Power amplifiers
6. Field generating antennas: Biconical, log periodic, horn or any other linearly polarized antenna system capable of satisfying frequency requirements.
7. An isotropic field sensor
8. Associated equipment to record the power levels necessary for the required field strength.

Along with the test equipment the standard has also specified the test levels. The test levels and the frequency bands are selected as per the electromagnetic radiation environment to which the EUT can be exposed when finally installed. The tests are normally performed in the frequency ranges 800 MHz to 960 MHz and 1.4 GHz to 6 GHz. The frequencies or frequency bands to be selected for the test are only applicable where mobile radio telephones and other intentional RF emitting devices operate. Following is the classification of test levels specified in the standard:

1. Class 1: Low-level electromagnetic radiation environment: Applicable to local radio/television stations located at more than 1 km, and transmitters/receivers of low power.
2. Class 2: Moderate electromagnetic radiation environment: Applicable to low-power portable transceivers (typically less than 1 W rating) which are in use, but with restrictions on use close to the equipment. A typical commercial environment.
3. Class 3: Severe electromagnetic radiation environment. Applicable to portable transceivers (2 W rating or more) are in use relatively close to the equipment but not less than 1 m. High-power broadcast transmitters are close to the equipment and ISM equipment may be located close by. A typical industrial environment.
4. Class 4: Portable transceivers are in use within less than 1 m of the equipment. Other sources of significant interference may be within 1 m of the equipment.
5. Class X: X is an open level that might be negotiated and specified in the product standard or equipment specification.

Test levels related to general purpose, digital radio telephones and other RF emitting devices are given as follows:

x is an open test level and the associated field strength may be any value. This level may be given in the product standard.