[TowerTalk] Symptoms of antenna interaction?

[Chuck Dietz]

Try the 6m perpendicular to the C3 to see if that helps. It could be placed
at the top of the mast for best separation and the 2m in the middle.

Chuck W5PR

On Tue, Mar 23, 2021 at 2:30 PM Al Kozakiewicz <akozak at hourglass.com> wrote:

> Still have a foot of snow on the ground, so I'm not quite ready to climb
> yet.
>
> See photos on QRZ page.
>
> I have 3 antennas on a 10' mast sticking a total of 8' out the top of the
> tower. From top to bottom, 2M7, 6M3 and a C3, all equally spaced.  All were
> tuned to resonance on the ground.
>
> Now up in the air, the C3 and 2M7 are fine, but the 6M3 is useless. The
> SWR is about 3:1 and Z=~70 ohms at the minimum for both.
>
> Is this symptomatic of interaction, i.e. feed point characteristics change
> while resonance frequency remains the same? If so, what is a recommended
> solution? The one possibility I haven't checked yet as it requires climbing
> is a bad rotor loop cable.
>
> Al
> AB2ZY
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