Topband: Cable shields

[Tom W8JI]

The statement CATV coaxial cables or cables with foil/drain shields do not 
have good shielding, because of transfer impedance and high resistance, was 
made a while ago here on this reflector. I think the statement was those 
shields are not good at MF or HF.

This past weekend, I modified a test fixture to test sample cables for 
common mode.

I compared two samples. One was an 8-foot long sample of two-year-old 
CommScope F6 dual-shield, and the other was a heavy copper braid RG6/U solid 
dielectric that was inside. The F6 was pulled out from a cut cable a week 
ago, one bonded foil overlaid with aluminum braid.

The cables were within a dB or two of each other.

http://www.w8ji.com/coaxial_cable_leakage.htm

73 Tom