Topband: Comments on High Performance RX Antennas for a Small Lot (Webinar)

JC n4is at
Fri Mar 4 08:57:48 EST 2016

Hi Rick

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
floor decrease.

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.


-----Original Message-----
From: Topband [mailto:topband-bounces at] On Behalf Of Richard
(Rick) Karlquist
Sent: Friday, March 04, 2016 12:38 AM
To: Topband at
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?

Rick N6RK
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