The disturbance source studied in the Radio Frequency Field-Induced Conducted Disturbance Immunity Test typically refers to the electromagnetic field from radio frequency transmitters. This electromagnetic field can act on the entire cable connected to the installed equipment. Although the size of the disturbed equipment is smaller than the wavelength of the disturbance frequency, I/O lines, such as power lines, communication lines, interface cables, etc., may become passive receiving antenna networks because their length may be several wavelengths.

It is assumed that the cable network connecting the equipment is in a resonant mode (λ/4 and λ/2 open or folded dipole). Sensitive equipment between cable systems is susceptible to the disturbance current flowing through the equipment, and this cable system is represented by a coupling and decoupling network with a common-mode impedance of 150 Ω relative to the reference ground plane (plate).

The measurement method simulates the electric and magnetic fields from actual transmitters by subjecting the equipment under test to disturbance fields formed by the disturbance source. These disturbance fields are approximated by the near-field electric and magnetic fields formed by the voltage or current generated by the test configuration. The coupling and decoupling device provides the disturbance signal to a specific cable while keeping other cables unaffected. This only approximates the actual situation where the disturbance source acts on all cables simultaneously with different amplitudes and phase ranges.

1. Radio Frequency Radiation Immunity Test Levels

The frequency range defined by the test levels is 150 kHz to 80 MHz. In the frequency range of 9 kHz to 150 kHz, measurement of induced disturbances from electromagnetic fields of radio transmitters is not required. The test levels are shown in Table 1.

The selection of test levels is mainly based on the electromagnetic environment in which the equipment and cables are actually installed. The classification of levels in Table 6-16 is based on the following.

a. Class 1: Low-level radiation environment. Typical levels from radio/TV stations at a distance and typical levels of low-power transceivers.

b. Class 2: Moderate electromagnetic radiation environment. Used for low-power portable transmitters (typical rating less than 1W) near the equipment. Typical commercial environment.

c. Class 3: Severe electromagnetic radiation environment. Used for handheld transceivers (≥2W) relatively close to the equipment but not less than 1m, high-power broadcast transmitters near the equipment, and possibly close to industrial, scientific, and medical (ISM) equipment. Typical industrial environment.

d. Class X: Open level specified by negotiation or by product specification and product technical standards for specific products. When selecting the applicable level, the consequences of equipment failure should also be considered. When the consequences are severe, a stricter test level may be considered.