[TowerTalk] Losses in parallel coax

[Mike Fahmie]

Assume 100 watt power level, imagine now that 50 watts is carried by each coax.  Assume each coax has 3dB loss at the test frequency.  Each coax will lose 25 watts. Summed at the output, there will be 50 watts, a 3db system loss.
Remember that the RF voltage in a matched system will be lower by a factor of 0.707 in the composite coax due to the lower system impedance. That results in half the dielectric (V^2) power loss (I^R is usually negligible).
-Mike-WA6ZTY

 
      From: Hans Hammarquist via TowerTalk <towertalk at contesting.com>
 To: towertalk at contesting.com 
 Sent: Thursday, August 4, 2016 10:50 AM
 Subject: [TowerTalk] Losses in parallel coax
   

 Jim, 

That's something I don't really understand. Why do you get the same loss in coax if you run them parallel? If you run "normal" wires in parallel you reduce the losses due to the lower current in each from the conductor RI^2 loss and the V^2 loss in the dielectric, even if that's not a big deal at, say, 60 Hz. Why not the same for coax? Yes, if I parallel two coax I need to use some matching to get the 50 ohm (or whatever I have).

Hans

 

 

-----Original Message-----
From: Jim Brown <jim at audiosystemsgroup.com>
To: towertalk <towertalk at contesting.com>
Sent: Tue, Aug 2, 2016 1:15 pm
Subject: Re: [TowerTalk] Flaky dipole



And as you probably know, the loss in dB in parallel runs of coax, 
whether connected in series or parallel, is the same as in a single run 
of the same coax.

73, Jim K9YC

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