IEC 61000-4-39 defines an immunity test in which a source of radio-frequency field is placed very close to the equipment under test. It was written to cover a situation that conventional radiated immunity testing does not reproduce: the increasing use of portable and mobile transmitters, including handheld radios, mobile telephones, wireless payment terminals and industrial remote controls, that are routinely operated at distances of a few centimetres from electronic equipment, well inside the near field of their antennas. The standard covers the frequency range from 9 kHz to 6 GHz and specifies the field generating devices, which are small antennas and probes positioned at a defined separation from the equipment, together with the field strength levels and the way the field is verified at those short distances, where the field is not plane-wave and the measurement is made with a calibrated probe rather than standardised far-field techniques. It describes the selection of test points on the enclosure, the orientation of the source, and the monitoring of the equipment. The test complements the far field method of Part 4-3 for products used in the vicinity of portable transmitters.