[TowerTalk] Circuit Board Question

[Jim Lux]

On 8/2/14, 1:10 PM, Steve Hunt wrote:
> Rick,
>
> I already corrected this misunderstanding once: for a 2:1 SWR the
> maximum voltage will be 1.414 times the matched voltage, not double! The
> minimum voltage will be 0.707 times the matched voltage.
>
> If V is the matched line voltage, Vmax=1.414xV and Vmin=V/1.414 giving
> Vmax/Vmin=2:1
>
> Steve G3TXQ
>
>

Power dissipation, though, will be 2x (which I think was what we were 
talking about..

My off the cuff question was more along the lines of "are the current 
maxima at the same place as the voltage maxima":  that is, is max 
dielectric dissipation going to occur at the same place as max copper 
loss dissipation, or are they going to be, say, 90 degrees apart.

In a matched line, voltage and current maxima occur at the same place 
because current and voltage are in phase.

But in a mismatched line that's not necessarily the case.

(Of course, Rick's "do you feel lucky" applies here.. I'd design for the 
worst case, but there might be some time where you know where the "hot 
spots" are going to be.)




>
>
>
>
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> On 02/08/2014 19:00, Richard (Rick) Karlquist wrote:
>>
>> For 2:1 VSWR, 2X is the worst case, which you would want to use for
>> design. In practice, it could vary from half to twice the matched
>> value for a short section of line.
>>
>
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