On 6/1/2014 7:29 PM, Mike Schatzberg wrote:
In the gigahertz region, the shield wires become even more important to reduce
structural return losses.
As you hinted at in early post on the topic, the leakage from coax is
generally quantified by the Transfer Impedance of the shield, which is
the ratio of the voltage on the shield to the differential current (that
is, the signal current) on the shield. The lower the transfer impedance,
the less the radiation (leakage) of the differential signal by shield.
The lower limit of the Transfer impedance is the resistance of the
shield at the frequency of interest, and the transfer impedance
increases with a shield that is less dense and has poor uniformity.
SO - for minimum crosstalk, a very robust shield is critically
important, and this is just as true at HF as it is at UHF.
73, Jim K9YC
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