[Prev][Next][Index][Thread]

(meteorobs) Temiscaming/Jim



Hi Jim,

Thanks for the reminders and the refresher. I had forgottem some of that.
Every once in awhile I go back to McKinley's and Kraus'  books and see what
might apply. Your message saves me doing that in the near future.

HOWEVER, I am still unconvinced that much of it is relevant to my
situations in Waubaushene and Temiscaming. I think this theory is great for
military installations with huge antennas with super-small beamwidths,
universities with radar facilities, and commercial enterprises where
optimizing the circuit affects how much the shareholders earn. For the most
part, these installations use point-to-point circuits. They can therefore
point the antenna to the optimum area in the sky.

On the other hand, the reality is that in Waubaushene and in Temiscaming
I'm using a small yagi that probably has more sidelobes than I have hairs
on my head.  <|:-)   The beamwidth is nothing to write home about either;
neither is the gain. I am also listening to whatever comes in. In general,
(because the antenna beamwidth is large) I have no idea what station I'm
listening to and therefore no idea where it is located. Based on all of
this, it is impossible for me to optimize the circuit. Because Steve is
doing more point-to-point type communications, and (I assume) using fairly
large antennas, he is in a better position to optimize his work.

In fact, one of the first things I do when I'm doing a 'mathematical'
version of my presentation is to put some of those equations on the screen
and then eliminate the uncontrollable factors (e.g. electron line density,
electron radius, diffusion constant, polarization coupling factor,
propagation angle, trail angle relative to transmission plane, etc.) and
show the audience that by eliminating these irrelevant (since you can't
control them) factors, you see what is important in a set-up like mine.
That is, wavelength, transmitter ERP, transmitter location relative to
receiving location, and receiving antenna characteristics. Electron line
density may be important to someone, but not to me. If the density is high,
then it is; if it's not high, then it's not. But there's not a damn thing I
can do about that, so why would I even consider it important?

In my set-up, I may hear signals reflected from stations hundreds of
kilometres apart, why do I care what the propagation angle is? I couldn't
change it if I wanted to.

As I mentioned earlier, most military, university and commercial
installations are point-to-point circuits. Therefore, they have control
over transmitter and receiver location. I do not. If, in a given situation,
I plot the locations of FM broadcast stations and find that there are more
stations in close than there are far away, what's the point in aiming my
antenna at the horizon? (No matter what the theory or equations say.)
Conversely, if I find lots of distant stations and only a few close
stations, why would I point my antenna straight up? You go with the logic
of a situation--not the matematics of an equation. None of the equations I
have seen considers the population density of multiple transmitter sites.
That was a factor in both the Waubaushene and Temiscaming tests. It's one
of the major reasons I chose those locations to do the tests. What I expect
we will find eventually is that we hear the same number of meteors in
Waubaushene whether the antenna is pointed up, down or in between--what
will change is *when* we hear the reflections (because different meteors
will be involved in the reflection process) and *where* the transmitters
are located (also because different meteors will be involved in the
reflection process).

As for signal amplitude and duration, I take whatever comes. All I can do
to change these is go lower in frequency or build an antenna with more
gain. Everything else--including transmitter ERP--is out of my control.

Although I understand your approach, the equations you quote are indeed
irrelevant to me and the tests we are conducting. There are times when
equations apply. But Waubaushene just 'ain't' one of them.

Having said that, I must also say that I appreciate the input from you and
the others (like Steve) who took the time to reply so far. One of the
things these messages do is make me think about things. And as happened
with something Steve said, I came up with a new idea about the value of
aiming the antenna toward the zenith.

I should also say that I save most of these messages (as I will yours, Jim)
because I re-read them every once in awhile--as I do the meteor books and
articles I have collected--and every now and again something jumps out at
me that I've overlooked before and I get a new idea or a fresh perspective.

In ending, let me pose a question. If you lived on a small, city lot where
you couldn't put up a horizontally-mounted antenna without overhanging the
neighbour's property or if you lived in a location where you were
surrounded by tall buildings, what would you do? Would you sit on your ass
and whine about how unfair life is because you can't optimize your antenna
for an imaginary propagation angle in some equation? Or would you put up an
antenna pointed at your zenith and make the best of the situation? (My
guess is that everyone on the meteorobs list would opt for the zenith (or
is that 'zenithal'?) solution.)

Take care. And keep the ideas coming.

Phil
P.S.
Oops!!! I just went to check something in your message Jim and I can't find
it. If you saved it, can you re-send it to me please.
To UNSUBSCRIBE from the 'meteorobs' email list, use the Web form at:
http://www.tiacdot net/users/lewkaren/meteorobs/subscribe.html

Follow-Ups: