Density of braid shielding

Question

Does the shielding braid density depend on frequency range to provide good cable shielding? I have read that braiding works well for low frequency but that at high frequency the effectiveness decreases because of holes.

Answer 1

Continuous shielding (with a conductor or foil wrapped all the way around the wires) is better than the other two common options which are braid or spiral. The more coverage you have the better it will do a high frequency and the more conductor crosssection you have the better the shield will do at high frequency.

It really depends on the cable though so if you need to compare cables usually the frequency specifications are available in the data sheet.

Another note: A nice thing about foil with a conductor is it can be easy to attach to a cable.

Answer 2

Yes, cable shielding effectiveness depends on the shield material (solid being better than woven or braided), as Voltage Spike said. Note that solid outer conductors (shields) made of copper, tinned aluminum or stainless steel provide much better shielding than any type of braid or foil.

Shielding effectiveness is also inversely proportional to frequency, with lower frequencies being easier to shield than higher frequencies, so long as the "victim" is far enough way from the EMI source so as to be in the far field. That means EM wave shielding.

But the best of shielding can be completely wasted by a poor choice of connectors (plastic instead of metal), and terminating the shield with a pigtail instead of a metal backshell that contacts the shield 360 deg around the cable.