Cable Shielding Effectiveness Measurement

For these products we primarily use two techniques the triaxial fixture method and the mode stirred method.

Cable shielding effectiveness measurement.

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. Measurements were made in the frequency range 0 5 to 100 mhz. Ventilation is another example and one that is usually problematic with regards to shielding effectiveness.

This method is effective for frequencies less than 500 megahertz. A shielding unit is inserted through the box s opening. It involves the use of a sealed box with an opening. Making accurate measurements is a challenge because shields have many different shapes and purposes.

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. The test method permits measurement of long specimens using high currents with a uniform current distribution along the cable shield. There could also be changes in compliance standards.

This is a typical margin recommended by various industry specifications. 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. The shielding effectiveness is measured by comparing the reading of reference and the load devices.

To verify the periodic calibration two gold standards are employed.