Thanks for reply. What is the benefit in hooking up two scanner radio optimized Ferret 8 Band antennas vertically, in parallel, and turned by a rotor? They both are still omnidirectional any way right? Why would this benefit?

JH

Thanks for reply. What is the benefit in hooking up two scanner radio
optimized Ferret 8 Band antennas vertically, in parallel, and turned by
a rotor? They both are still omnidirectional any way right? Why would
this benefit?

Stacking two omni-vertical antennas one above another can increase the
gain towards the horizon (where you tend to want it) at the expense of
gain at higher and lower elevation angles (where you usually don't
care very much). To get this improvement, though, it's necessary to
use a phasing harness which combines the signals properly in-phase and
preserves the correct impedance... and this is much more easily said
than done for a multi-band antenna! Do it wrongly, and you could
easily end up with a system that had *less* gain towards the horizon
than a single antenna would, at much greater cost.

Turning such a stacked pair (or even a single such antenna) via a
rotor seems nonsensical to me in most cases. The only case in which
it could make a very small amount of sense, would be if the antenna
(or stacked pair) is side-mounted on a mast or tower. The presence of
the mast or tower will cause the pattern to be somewhat less than
truly omnidirectional... there will probably be a partial null (a
"weak spot" in the pattern) in the direction of the tower. Rotating
a side-mounted stacked pair so it was on the opposite side of the mast
would change the "sweet spot".

The improvement in coverage would probably be small (from either
stacking, or rotating). Seems like a lot of expense to go to for a
small gain. From the manufacturer's point of view, it's probably a
great idea... they sell two antennas instead of one :-)

--
Dave Platt AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
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