Before sending an electronic product to a lab for compliance testing for EMI emissions, you can perform a precompliance (far-field) EMI measurement with a spectrum analyzer and an antennas. If the product's emissions above the amplitude levels set by national and international standards, you'll need to find the emissions sources to solve the problem. Antennas are physically too large to make measurement close to the circuit. Therefore, near field probes must be used to find the souce.

The model PS-400 Near Field probe set consists of two E-Field probes and a H-Field probe for board level radiated emissions testing. One of the two E-field probes is patented. It has a fine tip that allows noise measurement of pins on ICs and traces as narrow as 3 mils on a printed circuit board. The other E-field probe is used to find the vicinity of the highest emissions levels on the board. This probe has a higher amplitude sensitivity than the fine tip probe.

Once the location of the possible sources of EMI (Electromagnetic interference) is detected using this probe, the fine tip probe can assist the design engineer to pinpoint the exact circuit that might be causing the EMI.

Using these two probes in combination the design engineer can quickly find and suppress the EMI at the source, before resorting to other means of EMI suppression. The Loop probe allows detection of magnetic noise emanating from chassis seams, ribbon cables and connector pins.