Hi Glenn, I've only been using Beverages on 160m for 40 years, so this
is a somewhat partial and subjective view, but they certainly increase
the S/N ratio considerably for human ear reception of extremely weak
signals *when terminated correctly*. Usual gain is around -20 dBi, but
irrelevant because I use carefully-designed preamps to increase the
signal level back to the receivers to overwhelm locally-generates noises
from my neighbours properties.
I found that I could get almost as good results with phased rotatable
terminated loops, using Vactrols and phasing networks to tune the
characteristics, mainly null steering to reduce high-angle local
signals, and reducing human-generated noise and noise from the auroral
curtain up here at 54 degrees north. Those loops have a gain around -32
dBi when phased, but the gain in S/N is definitely worthwhile.
Beverages work *because* of the lossy dielectric soil beneath them, not
despite it.
E-field probe antennas and small loops also work very well to improve
the S/N on some paths. You need a selection of different antennas to
get best results for all directions. I also use multiple receivers
concurrently.
You also have to detune and terminated any transmit antennas within a
few wavelengths while you are on receive, avoid putting a station near
any large wire arrays such as power grid feeds or electric fences or
strained wire fences.
I agree that Beverages and other specialist receive antennas are
difficult to model, but luckily folks have been getting excellent
results since FOREVER without worrying about whether they can be
modelled. Having a way to adjust the terminating resistor is helpful,
and having the wire elevated the right distance above ground and having
it multiple wavelengths long is also helpful. but I've used
Beverage-on-ground antennas over poor soil with some success.
Using my receive antennas often bring signals up that are entirely
invisible and undecodable on the waterfall on transmit antennas.
--
Neil G4DBN
https://youtube.com/MachiningandMicrowaves
On 13/11/2023 21:41, robert evans LAST_NAME via wsjt-devel wrote:
When they built and installed the beverages they noticed they
had just as much noise as the other antennas if not more.
I modeled the Beverage and discovered it was a very high
loss antenna. The soil was the lossy element and if you
tried to reduce the loss by tuning the termination and
matching networks you compromised the front to back
ratios and lost directionality.
The performance of the Beverage was dependent on soil
characteristics and difficult to model and variable to
to due to rain etc.
We put an oscillator in the undesired direction.
Before a contest the termination and matching was
tweaked to null the oscillator in the park while favoring
European stations.
The Beverage is a lossy antenna with the least loss
in the desired direction when correctly terminated and
matched for the soil conditions.
BCNU DE N2LO~>
On 11/13/2023 11:45 AM EST Glenn Williams via
wsjt-devel<wsjt-devel@lists.sourceforge.net> wrote:
This is a theory question. There is a bit of FT8 on 160m. Does use of a
Beverage Antenna to get more signal raise the S/N value? Would that
antenna help with receiving weaker signals (a variation of that S/N
question)?
--73, Glenn, AF8C
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