EMEtä

EMEtä is a Finnish term often translated as "EM distance" or "EM proximity" and is primarily used in the context of electromagnetic compatibility (EMC). It refers to the physical separation between an electromagnetic (EM) emission source and a susceptible device or equipment. This distance is a crucial factor in determining the strength of the electromagnetic interference (EMI) that might be received by the susceptible device.

The strength of an electromagnetic field typically decreases with the square of the distance from the source. Therefore, increasing the EMEtä is a fundamental and effective method for reducing unwanted electromagnetic coupling between devices. In EMC testing and design, establishing appropriate EMEtä is essential for ensuring that a device will not emit excessive interference or be unduly affected by external electromagnetic fields.

Regulations and standards related to EMC often specify minimum separation distances or require testing at certain distances to verify compliance. For example, in radiated emissions testing, the measurement antenna is placed at a standardized distance from the equipment under test to simulate typical environmental conditions and ensure that emissions do not exceed permissible limits at that distance. Similarly, in immunity testing, the susceptibility of a device is evaluated when exposed to electromagnetic fields at defined distances. The concept of EMEtä is therefore integral to the design, testing, and deployment of electronic and electrical equipment to ensure their proper functioning in their intended electromagnetic environments.