The frequency measurement range of RE102 is 10KHz to 18GHz.

The standard EMI filter is designed to filter conducted emissions over the frequency range of 10KHz to 10MHz. This would lead one to think that the filter will not help much for the RE102 requirements.

This is true unless the filter is electrically and mechanically designed to attenuate the higher frequencies.

The power cord is often the major source of RE102 emissions. The good news is that this is generally an easy problem to solve. There are a few things that are necessary to implement the solution.

  1. The enclosure should be metal and “well-sealed”. Essentially you want to have a Faraday cage.
  2. The power line needs to have a filter that will block or send the high-frequency signals to a low impedance ground plane.
  3. An absolute requirement is to use feed through capacitors in the filter. These low impedance devices shunt the high frequencies to ground. They also block the propagation of HF signals along current-carrying wires bypassing the wires through interior bulkheads that present orifices small enough to block signals below 20 GHz.

The figure below shows a possible installation of a Mil-Std-461 filter, but there are many more configurations that will also work. The key thing is that the input to the filter must be completely isolated from the output of the filter. JMK has many of these filters. The filters can also be modified to meet almost any installation.

Mil-Std-461 filter