[TowerTalk] Re: coax as balanced line

[John Brosnahan]

>And, BTW,  the signal does not make a round trip when traversing
>parallel shielded lines,  it does travel through loss resistances
>which are equal,  and in parallel,  so the loss is cut in half
>using two lines, and to 1/4th using four lines.
>
>73,  Jim, KH7M


Jim, I really wanted to believe that it was this simple, but it isn't.
It doesn't matter how many lines you series or parallel--the signal
gets divided between the lines, the lines each do their loss
and then the signals get combined.  If you have to do some extra
matching on each end, then the losses of the matching networks
just make it worse.  It isn't just the ohmic losses that cause the 
problems.  The decreased copper losses trmain a fixed percentage
of the reduced characteristic impedance of the new line.

You can take my discussion for series (balanced lines of coax)
connections and invert them for parallel connections (unbalanced,
low-impedance lines).

73  John  W0UN


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