At 12:10 PM 8/19/1999 -0600, k6ll@juno.com wrote:
....
>
>Don't forget to double the benefit if any change helps also
>on RECEIVE. Multiply the benefit by X if the change helps
>on X number of bands.
>
Well, I dunno. Later in his message, Dave noted that a particular antenna
improvement on 160 benefited transmit only, because receive is atmospheric
noise limited. I believe that the same logic is also operative at least up
through 15 meters. At this stage in the evolution of my station (single
tribander, 2-el 40, 100-foot tower, 1 KW) I know there are many stations
that can hear me (and are answering) that I can't copy, because they are
masked by atmospheric noise.
I'm in a quiet location with a sensitive receiver, so I know that my
ability to work these stations is limited by atmospheric noise. Being a dB
or 2 louder won't help. I can improve directivity in the azimuth or
elevation planes, and that will certainly help with noise that is not in
the main lobe, but at some cost in flexibility and coverage of all of
Europe on one azimuth. I can try DSP, both to reduce incoherent noise and
to narrow the bandwidth (though that impairs my running capabilities).
Bottom line, on HF at least, is that I don't think antenna improvements
automatically deserve "double dB."
A last aside -- Rockwell's articles got me started on this, 33(!) years
ago, but re-reading them in the light of today's knowledge, the analysis is
fearfully oversimplified and the actual findings are questionable. At this
point I don't believe that there is a single, transferrable figure of merit
for station performance. What is important, I believe, is going through
the analytical process, assessing your station's strengths and weaknesses,
evaluating measures to counter those weaknesses, fitting them within your
unique set of local constraints, testing, and starting the whole process
over again...
73, Pete N4ZR
Sometimes a tower is just a tower
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