> How we test really depends on what we need to know.
In order to estimate what is the real elevation angle (3dB or HPBW) of an
antenna on far field, we should gather quantitative data.
Tom, what you are after with your measurements/observation?
>The key to accurate testing is time span of the tests over minutes and many
>days or months, not second by second in a short span >of life. It's silly to
>conclude a change with one day or even one week of testing, unless it is
>ground or direct wave.
If one will intend to use a statistical method to appreciate a phenomenon then
yes, the greater the time span and data quantity, the better results will be.
But...there is a big trouble with the big time span. The measurement system
should remain unchanged. If one system parameter will change during that time,
everything will be compromised! How to solve an equation with two or tree or
more unknown terms?
Te same thing is with the antenna and propagation measurements.
If one
intend to measure the antenna characteristics, only one parameter should
be changed at a time, the other should remain constant.
>The proper way is multiple tests at multiple times averaged over time. My
>tests ran at multiple times of day over many months >through many seasons,
>looking at pages and pages of logs.
>
>I didn't care if an S unit was 2 dB or 20 dB because I had no interest in
>picking quantative changes, I only cared which was >noticeably better over
>time. Also, as a factor, I would switch from omni to four square, which I know
>is very close to 6 dB. That >was always 1-2 S units, which is typical for the
>3-5 dB most people have for an S unit....not that the exact dB matters at all
>when >we are only after which is better.
>From the above statement, I realize that you were using the "A B" test (or A B
>C D etc. - how many antennas you used) for observing what was the best antenna
>for a particular QSO (DX, local, whatever). This way, you cannot say what was
>the "key factor" making that QSO. The antenna? The state of the ionosphere?
>The other side antenna? The ground beneath your or the other side antenna or
>other factors in that system.
I'm sorry to say but such data are useless for general or reproducible
conclusions, quantitative or qualitative.
With such data you cannot state that antenna A (B, C, whatsoever) is the best
antenna for DX (or local QSOs). This was true for your local conditions. Only
for your measurement system at that time!
On the same line of "fairy tales", it happens often to me that my ex-INV.V to
be better for USA than the INV.L. This is not a normal situation having in mind
that the INV.V has a strait up radiation. But the true facts are true facts,
that's all. In this case, what should I say? The INV.V is better than the
INV.L? Maybe:)
One interesting observed thing...
When I listen before and along my sun set, the stations from the east "start to
come" in the receiver with greater and greater intensity.
Using A B test between INV.L and INV.V antennas, ALWAYS (100% of the time) the
INV.L is getting the first and the strongest signal. Remember, I'm talking ONLY
of sun set not after dark. The same behavior was for QSOs (transmitting) with
those station.
As a funny thing, the hard part of those QSOs was to speak in russian language
because the most ukrainian operators does not speck english :)
What we could learn from that?
The mother nature give us a great tool to observe and measure our antenna
vertical radiation angle. The twilight, from day to night.
It is like a curtain or a tilted reflector moving around the earth which
reflects in one hop the signals between night and day. This explain why INV.L
is 100% of the time better than INV.V receiving the signals mentioned above.
Based on these observations I can state that INV.L has lower radiation angle
than the INV.V. This is a qualitative measurement.
If we could know precisely the ionosphere height, tilt at the reflection point
and its properties then a quantitative measurements could be conducted.
Unfortunately I don't have such data.
Look forward to hear about your experiments.
73 de YO3FFF
Cristi
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Topband reflector - topband@contesting.com
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