When it comes to EMC testing, specifications are far more than numbers on a datasheet. The EMC test specifications give essential details for designing an accurate and reliable test system. If a specification is unclear or does not match your setup, unexpected and costly problems can occur once testing begins.
Specifications Over the Full Range
When choosing a power meter, field probe, or amplifier, first define the frequency range and test level you need. These values may seem simple if you test up to 6 GHz, your equipment should too, but always look deeper. Some instruments lose accuracy near the limits of their range.
For example, an RF power amplifier may list 100 W output, but if it only delivers 47 dBm of linear power, it provides about 50 W in practice. If your testing requires a true 100 W across the entire frequency range, especially at lower frequencies, where typically more power is needed, this amplifier would not be suitable for your immunity test setup.
The same applies to E-field probes. One of our white papers shows that isotropic behavior, or anisotropy, is the largest source of measurement uncertainty (measured per IEEE-1309). Uncertainty often increases with frequency, sometimes causing errors up to 12 dB. A probe specified only at 100 MHz with a low anisotropy value may seem accurate but can perform poorly above 3 GHz.
In short, always check EMC test specifications closely. Contact the manufacturer or reseller if anything is unclear. Incomplete or vague specs can make comparing instruments much harder than it appears.