Dear Emanuele:

Do well on your exams. It is that time of the year here as well.

It occurred to me that I had quite forgotten that two dishes exist
associated with Reber. One is huge and the other is the 9.5 meter dish he
built himself. Both are at NRAO. Reber was a true scientist and a great
friend of my mentor, Kraus. Here is a story about him:
http://www.nrao.edu/whatisra/hist_reber.shtml

The maps he published just before the war, were studied by Dutch astronomers
who were sequestered during the war. After the war, the Dutch moved the
field forward. Reber's interests were many. You will note papers on beans,
for which he performed truly original work much of it while we were both at
NRAO. After dinner, when one learned not to leave the meat platter too
close to him, he would go off to inspect his research garden. He was a
collector - not quite the right word, but close - of early radios. I have
seen him get them working, construct a box that would just hold the radio,
and then store the boxed radio for a future museum. In his testing of old
(pre war) radios he discovered that one company had discovered stagger
tuning. His note on that subject caused a lot of noise.

His observation - known to everyone in the radio field - that the
ionosphere was most thin near VK7, resulted in his measuring radiation from
space at low frequencies well before satellites. His genius of seeing in
common knowledge new possibilities is his hallmark and one that I wish for
all who would push knowledge forward. He constructed all of his own
measuring instruments, which were strikingly beautiful. I spoke to radio
amateurs in VK7 while he was still alive and they told of how beloved he was
by the people of that island.

By the way, my first name is James, not John. I use "Mac" as it seems
more suited to this newsgroup than "Professor."

It is just possible that the sort of offset-feed antenna for receiving
broadcast signals is not common in Italy. If that is the case, a search
will uncover surplus dishes in North America. They tend to be in the one
meter size, which might be too small unless used in an array. I am told
that surplus, conventional dishes show up from time-to-time as
agencies/people move or up-grade. I like the idea of operating remotely.

Study, learn, plan, do, observe and you will learn even more. Consider
getting an amateur radio license.

Warm regards, James / Mac N8TT
--
J. McLaughlin; Michigan, USA
Home:
"Emanuele Colucci" wrote in message
...
Thank you John for this message.


J. Mc Laughlin ha scritto:
You are commended for initiative in wishing to have a radio
telescope. Crafting such an instrument can be an end into itself.
However, having an observational goal seems to be desirable if this is
more than a construction project. I recommend that you read the ample
literature that is available to help you design an observational goal.

Yep, I'm still documenting. Perhaps, there are alternatives to a Cas
antenna (Yes, I admit, because of exams I haven't crafted it yet, but for
me this is a very long term project), like a little array of offset
parabolic antennas.


Note that you need a large size if you are to achieve resolution,
which might not be an objective. I worked on the receiving system for a
system at NRAO at Green Bank, W.Va. that used a fixed, high gain antenna
to observe (once a day) the strength of one source. The antenna used had
a predictable gain and, with calibration, the system was able to provide
flux measurements (with an attendant uncertainty, of course).

This is interesting!
How much time did it take to make a complete radio stellar map?

Note that the first real radio telescope by Reber was a parabolic dish -
it still exists. (He was a really bright, innovative guy.)

Reber's parabolic dish is giant My site is situated in countryside, and
it could be able to host dishes of max 3 meters of diameter: the data
would be transmitted over the internet to my home (near Naples, ITA).


The presence of antennas used to receive satellite broadcasts that
use offset feeds should be considered. Such antennas can have desirable
antenna temperatures because of the placement of the feed while not
having feed-blockage.

Great. I'll watch for these antennas too!


Most important is the avoidance of re-inventing the wheel that can be
effected by serious study of the literature. That is where I recommend
that you start. Kraus' books on antennas and radio-astronomy could be a
good place to start. It would be wonderful to be young and have so much
learning to look forward to! After over 50 years of studying radio
related subjects, I am still excited.

Thanks again for reporting your experiences and the advices!

I haven't read Kraus book about radio astronomy: my sources are Collin and
some italian books by Flavio Falcinelli. But now I'll surely look for this
book too!


Greetings,

Emanuele Colucci