EMC Engineering: Signal Return and Shield Conduction Tests
Using external clip lead
Above: Clip lead attached to an oscilloscope or spectrum analyzer.
- Helps determine proper signal-return (or shield) connection back
- Connect one-meter-long clip lead to various shield connection points
on all I/O cable ports.
- Clamp a current probe around the cable (or measure the amount
- If no current is measured or clip lead has no effect on radiated
emissions, that shield connection point is connected back
to enclosure shielding okay.
Measuring plated shield
- Using a “four-point” probe permits one to verify sheet resistance and , therefore, the thickness of vapor-deposited (or plated) metallic
- A 4-terminal (for resistance) DMM (digital multimeter) is
- Knowing the thickness, one can calculate the shielding effectiveness,
given the manufacturer’s equation.
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Updated: Tuesday, 2020-03-03 22:13