A spurious emission can be defined as any signal produced by the radio that falls outside of the band on which the equipment is meant to be operating. A spurious emission is any radio frequency not deliberately created or transmitted, especially in a device which normally does create other frequencies.
Harmonics and Spurious Emissions generate radio noise. The radio signal can bleed onto other channels and frequencies.
Most RF devices have a requirement for allowable spurious content, based on Mil Standards, FCC regulations, NTIA requirements, or simply from performance needs. An ideal transmitter emits its signal only on the operating frequency in use and no where else. However, in reality, all transmitters radiate undesired signals, known as spurious emissions.
- Instability and Parasitic Oscillations
- RF leakage
- Harmonics
An unintentional radiator or incidental radiator is any device which creates radio frequency energy within itself, which is then unintentionally radiated from the device. A computer is a typical example, where spurious emissions may not be contained within the case. In the North America, active devices that are characterized as "unintentional radiators" are governed by Part 15 of the FCC regulations.