Topband: Comments on High Performance RX Antennas for a Small Lot (Webinar)
n4is at comcast.net
Fri Mar 4 08:57:48 EST 2016
As I told in the webinar it is a measured practical result, not a math
calculation.. I have a DDC SRD and several receiving antennas in a very
clean environment, only one TX antenna detuned, not other tower or Yagi etc.
I can switch from one receiving antenna to another and see how much the
signal is above noise.
When you remove noise for every direction due RDF, increasing RDF the noise
I can pick up a signal and measure db. above noise listening my TX vertical.
Then I switch to my vertical WF and the signal to noise ratio increase
average by 10 db., it has nothing to do with gain, just signal level against
noise level. Then I switch to my HWF and the SNR increase another 10 db.
from the vertical WF , it is average 20 db. better them the same signal
against noise on my TX antenna.
That is observations and measurements since 2009. Any time I can detect a
improvement I stick with it, and try something else to get another new
Looking into my records and associating it with RDF, comparing with 5dB RDF
from a vertical TX antenna, I come up with average 1,5 to 2 db. increase on
SNR for each dB increase in RDF against a vertical TX.
I it a practical empirical result, you can try and check it by yourself.
From: Topband [mailto:topband-bounces at contesting.com] On Behalf Of Richard
Sent: Friday, March 04, 2016 12:38 AM
To: Topband at contesting.com
Subject: Topband: Comments on High Performance RX Antennas for a Small Lot
In this webinar, it was asserted (without explanation) that for every 1 dB
increase in RDF, you get 1.5 to 2.0 dB improvement in S/N ratio. I've never
heard that before and don't even see how it makes sense. Actually, I don't
even know how you can make generalizations like that unless you are
describing a theoretical QTH with uniform isotropic noise. I'd like to
believe this is true.
Can someone educate me as to why I should believe this?
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