Electromagnetic interference (or EMI, also called radio frequency interference or RFI) is a disturbance that affects an electrical circuit due to either electromagnetic conduction or electromagnetic radiation emitted from an external source. The disturbance may interrupt, obstruct, or otherwise degrade or limit the effective performance of the circuit. The source may be any object, artificial or natural, that carries rapidly changing electrical currents, such as an electrical circuit or the Sun.
Have you ever wondered why the interference that you receive on the radio communications bands can sometimes disrupt the intended signals? Interference probability is based on the potential power transfer densities involved due to the proximity of equipment and antenna systems; the various transfer mechanisms, and equipment performance.
The electromagnetic transfer mechanisms may vary depending on modes of operation, propagation conditions, and other variables. The propagation paths that exist for signal transfer from the transmitters to a receiver within the RF environment of a radio communications band can be numerous.
Antenna-to-antenna coupling parameters may vary depending on antenna gain, directivity, beam width, side lobes, polarization, separation, propagation conditions of the path (path loss), etc. The receiver characteristics which influence performance include noise, dynamic range, sensitivity, selectivity (RF, IF), desensitization, adjacent signal susceptibility, intermodulation, cross modulation and spurious response susceptibility.