Hi Andy,
One thing I noticed listening, was an apparent lack of gain or noise
equalization between the two antennas. Either that or the LOG is WAY
quieter than the beverage. Adding an amplifier to an RX antenna, preferably
out at the antenna IS a bit of a pain, and needs careful work with a signal
source to get right, providing the only way to see exactly is going on.
Sometimes gain equalization shows one antenna as significantly better in a
given direction, or can reveal that an amplifier out at the antenna was
what was needed, not a new antenna.
LOGs and BOGs are lossy RX antennas and generally could use an amp.
One thing about LOGs is that they need to be modeled to account for the
severe velocity factor (VF) changes possible when laying on the ground. The
actual pattern can vary considerably depending on VF, and LOG patterns are
not at all intuitive. To figure out the modeling, you have to measure DOGs
to "tunej" the model., that is set the model's ground constants and wire
height above ground to match what you are getting with the DOG. There is no
cookie cutter size that fits all.
A while back, here in North Carolina, a brave band of locals went on a VF
study around the region to try and help explain the widely varying behavior
and effectiveness of BOG's. Measured VF's of DOG (dipole on ground) wires
laid on the ground varied from 45% to 85%, R at X=0 between 80 and 200. We
sometimes measured wild variations between various spots on the same single
piece of property, even after verifying no buried conductors. In a few
cases, we observed wide variation between N-S and E-W DOGs that had a
common center point.
Wide variation over time was seen with dry periods vs. wet, covered by snow
in winter, with and without accumulated seasons of falling leaf cover, laid
on grass vs. notched through the grass down to the dirt, laid on unmowed
grass during the growing season, vs. same during late fall and winter, laid
upon old leaf cover vs notched down to earth.
In the end the only way to size a 160 BOG was to lay down a DOG in the same
exact place and placement method as the intended BOG. Trim the DOG to get a
resonance (X = 0 ohms, not minimum SWR) at 1.140 MHz, and without moving
the dog wire, connect the wires at center and add the stuff at the ends to
turn it into a BOG. Those worked very well until the variations above set
in. Particularly falling leaves then becoming wet.
I had phased LOGS on Europe here, with all the issues above paid attention
to, including all the tuning falderal to get them to correctly phase. At
the start they were wonderful, but started to drift toward mediocre and
worse. Experience
was that they had to be retuned several times a year for rearward null, and
being under leaves basically shut them off. This necessitated blowing
leaves off the wires. A serious accumulation of snow degraded performance.
The best thing was to retune them before a contest.
AT some point other household issues controlled and the loops were retired
in place. And then the FCP thing started, soaking up all available time.
Those who live in the desert would be able to put LOGs down, tune them up
and keep them, unless it rained. Otherwise, especially if one's property is
heavily wooded, one has a cranky set of problems that go along with LOGs.
Good luck with it and 73,
Guy K2AV
On Thu, Nov 17, 2022 at 6:38 PM Andree DL8LAS via Topband <
topband@contesting.com> wrote:
> Hey,
> today a very nice receiving test and result.I compared my 80m long LOG
> direct on ground in a circle with my858 ft long beverage to JA.Dietmar
> HS0ZFV on 160m CW...
>
> https://www.youtube.com/watch?v=AnPnXuV0XmA
> 73, Andy DL8LAS
>
> www.dl8las.com
> www.swing-company-bigband.de/
> www.uni-big-band-kiel.de/
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