>>> Part 1 of 2...
 
-=> On 02-03-98  13:30, Jack Sargeant said to Ivy Iverson,<=-
-=>"About [2/2] Speculations & fact...,"<=-
 
Hi, again...
 
 II> Moonbounce, and point-to-point communication.  The 6 Meter, (50-54
 II> MHz), band, is borderline: it is generally local, however when
 II> conditions are right, it can be used for worldwide contacts.
 JS> This can be said for ANY frequency, but only a few are used on a
 JS> regular basis. The best radio propagation occurs between 500 kc -
 JS> 30mhz. The higher frequencies are not as conducive to "skip"
 JS> propagation. 
 
'Taint necessarily so.  VLF, (up to 30 KHz), is propagated along the
surface of the Earth, and in fact, through the Earth, rocks and even
water, and is not reflected by the ionosphere.  LF, (30-300 KHz), is
also propagated along the surface of the planet, and is not reflected
by the ionosphere.  MF, (300 KHz to 3 MHz - which includes the AM
broadcast band), is generally where penetration of the planet's
surface ends and ionospheric reflection begins, though the waves
still bend considerably around the surface.  Ionspheric reflection
is generally limited to times when the D and E layers of the
ionosphere, which absorb most radio waves, disappear, allowing the
combined F1 and F2 layers, (between 140 and 200 miles above the
surface and are good RF reflectors), to reflect radio waves back
to the surface.  This occurs mostly at night, however when there are
lots of sunspots throwing off ionizing particles, the lower layers
of the atmosphere becoem so heavily ionized that higher and higher
frequencies are reflected, even during the daytime, (the MUF or
Maximum Usable Frequency - the highest frequency reflected by the
ionosphere) goes up and communication distances increase.  There are
many factors which influence the condition of the ionosphere,
primarily the radiation from the Sun, which takes the form of free
electrons, and protons, which comprise the Solar wind, as well as
CMEs, (Coronal Mass Ejections), which, if they are strong enough and
happen to be aimed at Earth, can destroy communication satellites!
These same Solar events are responsable for the aurora, which are
caused by large waves of Solar particles hitting the Earth's magnetic
field, and following it to the poles, where they ionize the
atmosphere, causing the visible light in much the same way as low
pressure mercury vapor lights a flourescent lamp when ionized.  When
aurora are strong, (particularly when it's visible at lower
latitudes), it can knock out not only radio communication in the
polar regions, but can even knock out wire telephone and power
systems!  However, for radio communications at lower latitudes, the
auroral "curtains" can be used to reflect VHF and even UHF radio
signals for thousands of miles farther than they would normally
travel!  When reflected off the aurora, Morse code has a wavering
quality, and audio signals take on a unique ghostly quality because
of the movement of the ionized "sheets."
 
BTW, that fellow that I mentioned in the earlier part of this post
that I could have worked was in Southern Africa, and the frequency was
21.263 MHz, about 6 MHz below CB!  Even now, on the 2 Meter/ 147 MHz
radio beside me, (usually good for about 20 miles to a mobile or
about 50-60 miles to a repeater), is picking up signals from Chicago
and Holland Michigan, both around 150 miles away!  This is probably
due to a weather front in the area, causing ducting.
 
 II> (You are reading a message from an Extra-class Ham...
 II> ... and while I, like you, can only speculate about
 II> UFOs and ETs, but when I speak of Ham Radio, (or electronic
 II> communications in general, since I earned a Radiotelephone 1st
 II> class license over 30 years ago, and have worked for several AM,
 II> FM and TV stations, including as Chief Engineer of one), I know
 II> whereas I speak!)
 JS> La de da!  O;-) ...And your taglines are STILL too long, Ms 1st.
 JS> class ham. ...But you wore me out the last time, so don't comment.
 
What's YOUR area(s) of expertise, Jack?  (And my last line is trying
to bring more people INTO BBSing, not pull users away from your echos.)
OOPS!  U said not to comment...forget I said anything!
 
 II>    :-}
 JS> Thanks for reminding me we are off-topic. Go stand in the corner.
 
I don't have time... If I do that I won't get this into the BBS in
time for polling.  
 
 JS> Just a simple, "Hello, out there!" might take a thousand years to get
 JS> any kind of reply. ...And that is about all we dare to hope for.
 II> ...Or less than 5 years if it's one of our "neighbors."
 JS> How far into space can a radio telescope transmit to a similar setup
 JS> on a distant alien world? Could a radio signal even travel 1 light
 JS> year? ...Yet alone a thousand, or 10,000, or one million light years
 JS> that may be needed.
 
Of course it could!  Radio waves, like light waves, spread out and
become weaker... Square law: As the distance doubles, the energy will
decrease by the square, or a factor of 4, HOWEVER this assumes an
isotropic source: One which radiates equally in all directions like
a candle flame or a bare light bulb.  For a focused beam, like a
flashlight or an advertising skylight, I don't believe that it drops
as quickly.  Remember, broadcast radio waves, and particularly TV
signals are NOT radiated by an isotropic antenna, (which is only
theoritical anyway - it does not exist in real life!): They are
focused toward the horizon!  Of course, if a signal is being sent
to a satellite from a dish, the energy is focused into a beam of
something like 5-7 degrees wide.  And since reciprocity rules,
whatever you do to a transmitted signal is also done to any signal
received by the same antenna, (all other things being equal).  IOW,
if an antenna has a transmitting gain of 10,000, it will have the
same gain of 10,000 when receiving on the same frequency/band.
 
 II> As long as the receiving equipment is sensitive enough, there is
 II> NO LIMIT to how far a light - or radio - signal can be received!
 JS> I would think the further into space a signal penetrates, the more
 JS> dispersed it becomes. There must be a limit somewhere!
 
Yes, there is: dispersal.  (See above), but light - and radio - waves
continue FOREVER!  Just as our telescopes can see quasars billions of
light years away, radio waves from Earth will eventually travel the
same distance and more.  True, they get weaker with distance, but _IF_
you have a sufficently high gain antenna and a sufficently sensitive
receiver, you could still pick them out of the background noise.
 
 
 >>> Continued to next message...
 
___ Blue Wave/QWK v2.20 [NR]
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