Jeff, EZNEC confirms what you and Neil have found.
Modelling Neil G0JHC's antenna with 1000ft beverages at 12ft and 10ft,
offset by 30ft length-wise, shows almost identical patterns to a single
beverage.
Terminating both ends of the unused bev improves the f/b as one might
expect, but does not appear to change the basic pattern.
If you terminate both ends though, isn't it easier just to use one wire and
relay switch between the feeder and termination R?
73
John
-----Original Message-----
From: Jeff Woods
Sent: Wednesday, May 23, 2012 3:19 PM
To: topband@contesting.com
Subject: Re: Topband: 2 Parallel Beverages
I missed the original post, but if the question pertains to running two
independent beverages in opposite directions on the same supports - Yes. It
works well.
I began doing this last winter, adding shorter, opposite direction beverages
to my NE and NNW (EU and JA) antennas. Performance in the primary
directions is not compromised by any discernible amount. The antennas are
completely independent, sharing only the PVC support mast. The two
"secondary" antennas share a feed point (DC relay switched) where the two
primary antennas cross. The two primary antennas were up and running before
the secondary directions were added. No changes in performanceof the primary
antennas was noted after the addition of the shared secondary wires.
>From a theoretical point of view, this is no different than the operation
>of a typical 2-wire bi-directional array that relies on either wire working
>independently as a single-wire beverage in generating the common-mode
>signal.
Jeff W0ODS
Somewhere in Iowa
>
>> For various reasons I am considering two single, parallel but 180deg
>> opposing direction beverages on the same supports rather than a single
>> switchable bidirectional beverage. The bevs would be separated by 12 to
>> 18 inches or so. I've read that parallel bevs present performance
>> degradation issues but has anyone had any experience with this type of
>> setup versus the traditional bidirectional beverage? Thanks for reading
>> this and for any thoughts you could offer.
>> Mike W2LO
>
>
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UR RST IS ... ... ..9 QSB QSB - hw? BK
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UR RST IS ... ... ..9 QSB QSB - hw? BK
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