Topband: BOG questions

[Guy Olinger K2AV]

Given that BOGS are right at root level, the velocity factor along the
BOG wire will be somewhere between 45 and 75%, most often toward the
50% end of the range if it's pushed down good in the grass to avoid
mowing, or notched into the dirt.

That means that the accumulated wave on the wire is NOT moving as fast
as the incoming, and it is possible to start REVERSING the pattern by
extending beyond 200-220 feet.  On a long BOG there alternating zones
where the incoming wave is first adding to and then taking away from
the wave on the wire.  This little known, unpublished phenomenon is
probably responsible for the quite variable anecdotal results with
BOGs.

 A BOG is a single band antenna.  An optimal pattern on a BOG is NOT
obtained by the same process as a beverage.  For 160m put down 220
feet, get your ground at both ends by burying two 20' bare wires at
opposite right angles to the main wire.  Terminate the far end with a
pair of 450 ohm beverage termination resistors in parallel, and use a
4:1 isolation transformer at the feed end.  Do NOT ground the feed
shield anywhere near the transformer.

The output of a BOG is quite low.  You will probably need to use an
amplifier.  A remote powered preamp with an isolation transformer
right at the feed is the best idea, to establish the signal to noise
at the BOG.

Contrary to its name a BOG is not JUST a wire designed as a beverage
that is laid on the ground, and should just work.

Use NEC4 to model it and you see right away just how UNLIKE a raised
beverage it is.

73, Guy.

On Tue, Oct 19, 2010 at 7:57 AM, Pete Smith <n4zr at contesting.com> wrote:
> I'm thinking of a BOG for this season's RX antenna, after becoming
> thoroughly disillusioned with my K9AY loop experiments.  Problem is, I
> can only get about 350 feet on the right azimuth (to Europe) and to
> continue to a full 580 feet or so, I would need to do a 20-degree dogleg
> to the right.  I'm wondering if anyone out there who has NEC-4 can
> advise on how this would affect the pattern and the terminating
> resistance.  My NEC-2 won't handle it, of course.
>
> --
> 73, Pete N4ZR
>
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