Near-field probes act like wideband antennas, picking up radiated emissions from components, PCB tracks, housing openings or gaps and from any other parts that could be emitting RF energy. Scanning a probe over the surface of a PCB assembly or housing quickly identifies locations which emit electromagnetic radiation. By changing to a probe with a smaller size, the source of the emissions can be narrowed down further. The probes can also be used for for RF immunity tests, by feeding a RF signal into the probe and radiating it into potentially vulnerable areas of the circuit. The probes can also be used for repair or debugging, to track down faults in RF circuits by non-contact measurement of RF signal levels.