[TowerTalk] DB's, ad nauseam

[wa4dou@juno.com]

Hi Gang,
  Tom (W8JI) is right when he says , you can tell a subject that many of
us are very interested in and passionate about. 

  I think we are all looking for understanding and many bring ideas and
thoughts to the table that are good, valid, and worthy of consideration.
Those who have suggested that we are somewhat divided by "semantics" are
correct. One of the reasons that scientific "jargon" is necessary in a
particular discipline, is the necessity to be able to communicate very
precisely and accurately. There are those who don't care much for
anecdotal information but we all enjoy hearing or reading it to some
extent. Yet the very same lack of preciseness, in anecdotal information ,
is often conveyed in attempting to share direct scientific evidence to
support some view because our ability to use the language varies.

  It shoud be clear to us, on the face of it, that we all are keenly
interested in the same info, whether we're serious( even rabid) or casual
 dx'ers, contesters, qrp'ers, etc. We all have a vested interest in
trying to achieve the very best results that we can with what we've got
or can get, up to the point where financial or pragmatic concerns and the
law of diminishing returns kick in( and our own satisfaction levels are
reached). Serious contesters are like "hotrodders", anything that can
shave another 1/10th sec. off  of the ET, is viewed as very desirable.
Nothing wrong with that. Some qrp'ers and dx'ers see things exactly the
same way. Some of us enjoy participating in all these endeavors
seriously, casually or some state inbetween. 

  It has been my contention that a db is a very small unit of measure, is
barely discernable(in and of itself) and of little significance. Other
opinion varies. Other arguements bring out that atmospheric and man made
noises are very limiting factors, as is qrm, thus necessitating more f/b
& f/s ratio along with more gain in order to reach the next layer of
signals. Feedlines are very important. Angles of radiation are very
important. It is my belief that antenna height is the single largest
determining factor in performance over a particular path. Indeed , we
know there is such a thing as an antenna being too high.

  It isn't enough to merely state that a db is/is not very significant
unless we're talking using the very same antennas at the same height, at
both ends of the path. If what we really mean to say is that , in
stacking 2 or more antennas, we're picking up 1 or 2 or 3 db gain, that
cannot be stated so easily or compared in the same way because the
outcome can be quite different. On the one hand , all we're comparing is
the relative difference between two power levels. On the other ,we're
comparing two power levels at differing angles of radiation. We all know
there is no such thing as a perfect mirrorlike reflection going on in the
ionsphere. Indeed it varies not only time to time but also angle to angle
and time to time. Sometimes it appears to be quite linear and sometimes
very non linear. Its too simplistic to say that i raised my antenna gain
1 or 2 or 3 db, or whatever, and what i heard is an accurate
representation  of that theoretical change. Sometimes, due to the non
linear reflectivity, the change may actually be greater.

  

  There really is a wealth of knowledge to be found and shared on TT. I
enjoy this reflector much more than most of them. I wanted to write more
but gotta do some things around the house and have no time left today to
devote to it. 73 Roy WA4DOU
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