Thanks Andrey you have confirmed my suspicions but.
>And RF signals from Back direction of
reception is not "injected" at feed point, so direct multiplication of
attenuation by length does not play here.
It seems to me that All the signals from the back ( two transformer
receiver end) direction come from
the reflection transformer and therefore travel the full length of the
transmission line so I believe that
direct multiplication of the attenuation would be appropriate. If the signals
are down 6 dB in 300 feet would
not they be down 12dB in 600 feet? Signals from the front (reflection
transformer end)) however do not
use the transmission line except as a termination resistor. Perhaps because of
reality versus theory in
actual practice you only see 9 dB, I dont know? Wonder what it is on 80 meters?
Am I missing something here? Perhaps you meant RF signals from the front,
signals from the direction
of the reflection transformer end which would be true.
I know that Beverages with this wire work OK and are useful for many,
however at my location I have
a Bidirectional (1Kft) with the reverse direction toward JA. It is made from
aluminum fence wire with fairly low loss.
At times here in the early a.m. this antenna drops clear into the noise floor
of the receiver and its low noise
preamp. I have verified this with other types of antennas. It is so quiet in
that direction (over the Cascade
mountain range and then Pacific ocean) that I often hear the Hyperfix low power
navigation system in the
Bering sea UA0 area. So my thoughts are to use caution if you are attempting a
low noise direction with a
longer antenna of this material as it depends on the noise floor of the QTH as
you have pointed out.
You may never know just how quiet your QTH is if you dont try something
better. It seems to me you cannot
verify that your antenna is above the noise floor just by connecting it to the
RX with all the losses involved.
What ever way you look at it there is a lot of loss in the reverse
direction! About 2 dB per100 feet as I see it.
I still wonder about the incorrect termination effects due to losses and its
affect on the RDF/pattern.
It seems to me we all wait for that magic moment when it gets really
quiet and we hear the one DX call we never
thought we would hear. To me, I dont want to give away 5 to 10 or more dB of
my system noise figure when I dont
have to because I wait for that very magic moment every day! YMMV
Lee K7TJR Oregon
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