On 1/25/2012 5:59 PM, Carl Moreschi wrote:
he reason open wire line has less loss is that the dielectrics for true open
wire line is air.
FALSE! It's the ratio between the RESISTANCE and the IMPEDANCE of the
line. High impedance lines result in lower current for the same power,
and below UHF, virtually ALL loss in a transmission line is I squared R
loss in the conductors.
The only time that dielectric loss matters at HF (or even VHF) is when
the dielectric is WET. Window line exhibits high dielectric loss when
it gets wet. Coax exhibits high dielectric loss when the INSIDE of the
coax gets wet (and the copper corrodes, which increases the resistance,
which increases the loss.
73, Jim Brown K9YC
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