Cable Shielding Effectiveness Measurement

To verify the periodic calibration two gold standards are employed.

Cable shielding effectiveness measurement.

This method is effective for frequencies less than 500 megahertz. This is a typical margin recommended by various industry specifications. Ventilation is another example and one that is usually problematic with regards to shielding effectiveness. The method is offered as a standard technique for measuring the shielding effectiveness of shielded cables.

Measurements were made in the frequency range 0 5 to 100 mhz. The shielding effectiveness is measured by comparing the reading of reference and the load devices. The test method permits measurement of long specimens using high currents with a uniform current distribution along the cable shield. Cable interconnects which allow cables inside the cage to connect to cables outside may undergo modification for additional connectors that damage the shielding integrity.

For these products we primarily use two techniques the triaxial fixture method and the mode stirred method. It involves the use of a sealed box with an opening. There could also be changes in compliance standards. Measurement method for determining shielding effectiveness of cable feedthroughs.

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. Our most common request is to measure se for connectors and cables. 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. A plot of the chamber s dynamic range is shown in figure 2.

An efficient and repeatable measurement method for determining shielding effectiveness of cable feedthroughs based on the use of nested reverberation chambers is presented.