On 4/26/2013 11:11 AM, Carl Moreschi wrote:
Jim, if this were true the loss for RG8 for 28 mhz would be the same
as 14 mhz. But they are not the same. 28 mhz is about twice the loss
as 14 mhz.
What am I missing here?
Skin effect. The resistance in the equation is the resistance at the
frequency of interest, which is a multiple of the DC resistance, and
follows well known equations. The primary factor causing bigger coax to
have less loss is the o.d. of the shield. The larger diameter center
also helps. We LOOK for coax with low DCR, because that combines with
skin effect to determine the resistance at the frequency of interest.
73, Jim K9YC
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