Radiated radio frequency immunity

The purpose of the test is to verify the ability of the device under test to function correctly in the presence of modulated external electromagnetic fields. This test simulates disturbances generated by radio transmitters, cell phones, cordless phones, walkie-talkies, devices emitting RF disturbances nearby, as well as sources of industrial radiofrequency electromagnetic fields. The frequency range considered is typically 80MHz to 6GHz, but this range may vary depending on the devices under test.

In order to test a device for immunity to radiated RF disturbances, the device under test (EUT) is exposed to a defined radiated electromagnetic field. To avoid external influences from the environment and radio services, as well as for reasons of personal safety, these tests must be conducted inside shielded chambers made anechoic to prevent reflections of the electromagnetic wave generated.

The test setup is described in the figure below; based on the reference data recorded during calibration, the required test level and/or intensity are adjusted by the control software for each frequency. To this end, the signal is amplitude-modulated with a sine wave (typically 1 kHz 80%). The verification of the functionality of the EUT is performed manually (through a camera) or, if possible, automatically through instrumentation for analyzing the EUT's performance.

To ensure the reproducibility of immunity tests, standards require that the generated field be homogeneous. The anechoic chamber must ensure a homogeneous field within an area of ​​dimensions 1.5 m x 1.5 m for a distance ranging from 1 m to 3 m from the antenna. If a smaller surface is sufficient to ensure the exposure of the EUT and its connecting cables, then the homogeneous field can be reduced to 0.5 m x 0.5 m. The surface of the homogeneous field must be located at a height of 0.8 m above the floor. To ensure accurate probe readings, measurements are performed without modulation and with an empty chamber.

The standard

EN 61000-4-3
Titled "Electromagnetic Compatibility (EMC). Part 3: Test and measurement techniques. Section 3. Immunity tests for radiated radio-frequency electromagnetic fields," defines the test methodology and the characteristics of the test environment. Product technical committees then identify severity levels in terms of electromagnetic field levels in V/m, frequency range, and modulation type to be applied for the specific type of product or product family, based on specific product standards.

emissioni radiate a radiofrequenza

emissioni radiate a radiofrequenza