I run a 500' BOG that shows excellent directivity and sure doesnt need a
preamp. Velocity factor is determined by the ground beneath it and since
mine is over rock only 8-24" down it might as well be bare rock.
As Ive said on here several times when others like to claim only a specific
length works...one size does not fit all. Neither would I put one IN the
ground or use bare wire.
For the OP Id suggest running a pair of BOGs, one 200' N and the other 200'E
and see how they work. Then connect together. Several possibilities exist
including a loading coil.
Another BOG experiment I havent had time for yet is a 500' 2 wire reversible
well out in the woods for possibly full local crud reduction.
Carl
KM1H
----- Original Message -----
From: "Guy Olinger K2AV" <olinger@bellsouth.net>
To: "Max Cotton" <airradio@dsl.pipex.com>
Cc: <topband@contesting.com>
Sent: Saturday, September 22, 2012 2:17 PM
Subject: Re: Topband: Dogleg BOG antenna.
BOGs can be as short as 195 feet for 160. They do NOT work the same
way as beverages because the velocity factor laying against ground, or
in it, is so low. VF on BOGs has been measured as low as 45%, more
often around here 55-65 percent. On longer BOGs in the desired
direction this can cause phase on the wire to be opposite phase
incoming at points along the wire. Depending on ground and whatever,
longer BOGs can lose front-to-back entirely or even reverse pattern.
Folks have had good success around here with 200 to 225 foot BOGs.
These generally have good F/B and usually quite good local noise
quieting. Remember to get the BOG down next to the dirt.
You may need a preamp for a BOG.
73, Guy.
On Sat, Sep 22, 2012 at 10:59 AM, Max Cotton <airradio@dsl.pipex.com>
wrote:
I am going to try to place a BOG antenna in my local neighbourhood, as I
don't have a 650+ foot garden I thought the most inconspicuous antenna
would be a BOG, however I have to 'Dogleg' it, it has to run for 200 feet
North, then 200 feet East and the remainder North again, I only have a
maximum run of 700 feet. I will terminate it with a 200-470 Ohm (select
test) resistor at the far end, I have to run this along a wooden fence
line opposite a metal mesh fence about 10-15 feet away for the entire
run, this is towards the East. The mesh fence is enclosing an industrial
area with a footpath running around that enclosure. My intended BOG will
be on the side of this footpath away from the metal fence. Maybe I am
wasting my time, has anyone done anything like this, I do have a
North/South 'Inverted L' antenna but it is not brilliant for TopBand as I
can only ever hear UK and EU stations and normally not even those. I can
base load the 'L' but that is not brilliant. Ground conduc
ti
vity is good as I am about a mile away from a river and 3 miles from the
sea, good for HF but maybe not so good for LF bands. Maybe just adding a
few more topband radials to my 'L' may work for the moment. Ideas on
this anyone? QTH is South England.
73 Max
M0GHQ
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