EMC.

Natural sources of EMC problems can include thunderstorms, volcanoes, electrostatic discharges, the sun and background radiation from space.

There are natural sources, intentional emissions (e.g. mobile radio, radar, television and radio stations) and unintentional emissions (interference emissions, e.g. from switching power supplies, switching frequencies and their harmonics).

Conducted interference (signal interference) is interference that is transmitted via electrical lines, while radiated interference is transmitted via electromagnetic waves in the air.

EMC measurement during development is important because it is generally more cost-effective to solve design problems related to electromagnetic interference at an early stage of product development. Expensive redesigns and project delays can thus be avoided. With pre-compliance measurements, signal emissions from electronic components can be analyzed at any time in order to take corrective measures in good time.

Pre-compliance tests are recommended to identify potential problems at an early stage of development. The EMC conformity test then represents a much smaller hurdle. Redesigns, delays and additional costs in the later project phase can be avoided. Pre-compliance tests allow a detailed analysis of the signal emissions at any time so that appropriate corrective measures can be taken.

The formal EMC conformity test is usually carried out by certified test laboratories, but in some cases can also be carried out by the manufacturer. Conformity tests must meet the strict requirements and precise procedures of the EMC standards. As this requires special equipment as well as anechoic chambers and qualified personnel, conformity tests involve high costs.

Both the pre-compliance test in the development laboratory and the formal EMC conformity test require the use of standard-compliant test equipment and measurement methods in order to carry out reliable interference signal and immunity tests. The most important measuring devices include radio interference measuring receivers (EMI receivers), signal generators, broadband amplifiers, antennas, network simulators, oscilloscopes, vector network analyzers, spectrum analyzers and EMC scanners. In addition, "near-field probes" (H- and F-field probes) and special EMC software are used.

Various parameters such as the frequency range to be measured, the resolution bandwidth or the number of sweeps per measuring point are relevant for an EMC measurement. These are set on the spectrum analyzer, for example. The frequency range also determines the selection of the near-field probe. As the number of sweeps increases, the possibility of detecting sporadic signal interference also increases. This extends the measuring time.

A "limit line" is a borderline that defines the maximum permissible level of electromagnetic interference for a specific device or application. This line is used to check the conformity of the device.

Typical causes of EMC problems are unsuitable or improperly shielded cables, inadequate earthing, poorly designed circuits and non-compliant electronic components.

EMC problems can be minimized, for example, through the use of shielding, filtering, proper earthing, the use of EMC-compliant components and compliance with design guidelines for EMC.

Electromagnetic interference (EMI) is caused by unwanted electromagnetic fields. They can impair the signal quality and proper functioning of other electronic devices. In order to minimize EMI radiation as a whole, local emission sources on the integrated components must be identified and eliminated at an early stage. Electromagnetic interference radiation is assessed using measurements with special near-field probes (H- and E-field probes). As part of the pre-compliance test, this ensures that the emissions are compatible with the applicable EMC norms and standards.