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W5DXP > ANTENN 20.05.05 21:34l 32 Lines 959 Bytes #999 (0) @ WW
BID : 42860F33$1_2
Read: GUEST
Subj: Re: High Impedance Feedlines = Lower Loss - Why ?
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Sent: 050514/1447Z @:G8LMC.AMPR.ORG HamServ V2.66
Reg Edwards wrote:
> You will get all sorts of technical reasons for lower loss. But
> essentially -
>
> The wires in high impedance balanced pair lines are thicker than the
> inner conductor of coaxial lines.
>
> Thicker wires mean lower resistance.
>
> Lower resistance means lower loss.
That is true. But the number one reason that matched line loss
for 450 ohm ladder-line is lower than matched line loss for RG-213
at HF is the effect of (characteristic impedance = load) which is
the same effect as Ohm's law.
Given RG-213 vs 450 ohm ladder-line the losses are *roughly*
equal when:
SWR(coax)/50 = SWR(ladder-line)/450
or, in general, when:
SWR1/Z01 = SWR2/Z02
--
73, Cecil http://www.qsl.net/w5dxp
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