Will 4% Steps Find Radiated Susceptibilities?

CISPR Publications 24 and 35 allow radiated and conducted immunity tests to be performed using I% or 4% steps. This article looks at measured radiated immunity test data to determine the typical shapes of radiated susceptibilities for multimedia equipment. The authors consider what those shapes tell us about the validity of the 4% step method.

Harmonic Measurement for IEC 61000-4-3 and other Radiated Immunity Standards

In the rush to complete RF immunity testing on schedule, it is not all that unusual to overlook inherent test equipment limitations. While some test equipment characteristics such as power amplifier harmonics are obviously a limiting factor, the broadband characteristics of antennas, directional couplers, power meters and isotropic field probes can hardly be considered a limitation for most applications. However, when used with power amplifiers exhibiting significant harmonic distortion in Immunity test systems, the broadband characteristics of these devices can result in measurement uncertainty and unacceptable errors.