On Sat, 11 Oct 2003 17:37:14 -0500 "Mark Beckwith" <mark@concertart.com>
writes:
> Hello sages of RF wisdom. I have one for you. Not being an RF
> engineer,
> the solution escapes me:
>
> I have two identical antennas on one tower at different heights.
> They each
> have feedlines coming down to the bottom of the tower.
>
> If I wanted to feed these two antennas in phase, is there a way to
> figure
> out how long a piece to add to the lower antenna's feedline so it is
> in
> phase with the higher antenna? The velocity factors of the
> feedlines are
> unknown. The feedlines are not the same material.
>
> I have a dummy load, one of those Autek RF-1s and an MFJ antenna
> analyzer
> with two meters (SWR and impedance).
>
> Have at it. Thanks in advance.
>
> Mark, N5OT
>
> PS If it matters, the antennas are for 10M and one is at 50 feet and
> one is
> at 100 feet.
There is (or at least, was) a procedure for
phasing dissimilar antennas on the
array solutions web site. It involves
a dual-trace scope, and transmissions
from a nearby ham.
Dave Hachadorian, K6LL
Yuma, AZ
_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
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