Electrical equipment inevitably generates electromagnetic emissions that can interfere with the surrounding environment, including the power grid and nearby devices. Understanding the distinction between conducted and radiated emissions is essential for compliance with international standards such as FCC Part 15, CISPR 11, and ITU‑R recommendations.
Conducted emissions are the unwanted high‑frequency currents that a device injects into its power supply line. They travel along the power cord and can propagate through the entire distribution network, potentially causing disturbances in other equipment connected to the same supply. Devices are typically measured on their input conductors using a spectrum analyzer to verify that the emission level remains below the limits specified by regulatory bodies.
Radiated emissions arise when a device emits electromagnetic energy into the surrounding air. These fields, often in the radio frequency (RF) range, can interfere with nearby electronic equipment such as radios, televisions, and communication devices. Radiated emission testing is performed in anechoic chambers, measuring the field strength in volts per meter at specified distances from the test fixture.
