Cable Shielding Effectiveness Measurement

The test method permits measurement of long specimens using high currents with a uniform current distribution along the cable shield.

Cable shielding effectiveness measurement.

A shielding unit is inserted through the box s opening. There could also be changes in compliance standards. Making accurate measurements is a challenge because shields have many different shapes and purposes. This is a typical margin recommended by various industry specifications.

Measurements were made in the frequency range 0 5 to 100 mhz. For these products we primarily use two techniques the triaxial fixture method and the mode stirred method. An efficient and repeatable measurement method for determining shielding effectiveness of cable feedthroughs based on the use of nested reverberation chambers is presented. The method is offered as a standard technique for measuring the shielding effectiveness of shielded cables.

Measurement method for determining shielding effectiveness of cable feedthroughs. To verify the periodic calibration two gold standards are employed. Ventilation is another example and one that is usually problematic with regards to shielding effectiveness. Cable interconnects which allow cables inside the cage to connect to cables outside may undergo modification for additional connectors that damage the shielding integrity.

It involves the use of a sealed box with an opening. The measurement method is validated by comparing measurements on an isolated conductor penetrating the shield with a simple theory based on basic circuit theory in combination with antenna theory. Our most common request is to measure se for connectors and cables. A plot of the chamber s dynamic range is shown in figure 2.

When a cable specification calls for 90 db of rf shielding the 100 db dynamic range allows a 10 db margin in the measurement range.