RF Field Probe Selection For EMC Testing

By Jason Smith and Pat Malloy, AR

Often underestimated, RF field probes are critical to the implementation of a proper radiated immunity test system. All too often, system specifiers gloss over this essential element after having spent a considerable amount of time and energy selecting components required to “generate” the required RF field. After all, what good is an RF field if you can’t reliably measure it?

In an effort to simplify the process of probe selection, this article will focus on the salient specifications of RF field probes. Given a thorough understanding of how RF field probes are specified, one can then make informed decisions as to which probes are best suited for a particular application.

RF Field Probes Specifications
Frequency Response is undoubtedly the most important probe characteristic. It is defined as the frequency range the probe will respond to. Since no probe can provide a completely flat response across the entire frequency range, this spec is always accompanied by a tolerance figure, generally provided as a ±dB allowable variation band. An example of a typical frequency response is shown in Figure 1. The frequency response shown in Figure 1 is that of an actual probe designed to cover a heavily used frequency range. If the probe does not cover the entire frequency range of the test application, multiple probes may be required.

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•Application Note: RF Field Probe Selection For EMC Testing

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