[TowerTalk] Double Coax Runs to Reduce Loss?

[Jim Brown]

Exactly right. The good reason for using parallel runs of coax is when 
you need transmission line of double or half the Zo of commonly 
available cable. Two applications I can think of are 1) short lengths to 
provide impedance transformation and 2) long lengths to feed an antenna 
whose feedpoint has that impedance.

For two cables fed in parallel, Zo is divided by two. For two cables fed 
in series (that is, feeding from one center conductor to the other with 
the shields tied together at both ends), Zo is multiplied by two.

73, Jim K9YC

On Wed,12/21/2016 10:12 AM, Jim Thomson wrote:
>   But for greater power handling capability.. just use bigger coax to begin with,
> then you also get the benefit of lower loss coax.  Lower loss coax is the ticket
> for both RX  + TX.....esp on long runs .