ARLA/CLUSTER: Construir uma Antena Loop para escutar Júpiter.

[João Gonçalves Costa]

Loop Antennas

Loop antennas are a very controversial topic among Jupiter radio astronomers.
Some say it works, some say it doesn't - if it works for you, compare your results with those from people with dipole(s) or yagi's made during a coordinated observing session (announced on the RadioJOVE maillist) and let us know the results on the RadioJOVE maillist, SARA maillist or in the forum<http://www.jupiterradio.com/j/forum/>.

________________________________
[http://www.jupiterradio.com/antenna/LOOP.JPG]
________________________________
SIGNALS FROM SPACE

IS ANYONE OUT THERE?

[Connections]<http://www.jupiterradio.com/jove-loop-antenna.php#connect>, [Challenge]<http://www.jupiterradio.com/jove-loop-antenna.php#challenge>, [Flash Fact]<http://www.jupiterradio.com/jove-loop-antenna.php#flash>, [Teacher's Notes]<http://www.jupiterradio.com/jove-loop-antenna.php#teacher>

________________________________
Listen for signals from Jupiter with:

 *   6 pieces of wood 4 cm x 8 cm x 183 cm (for square frame)
 *   5 pieces of wood 4 cm x 8 cm x 80 cm (for upright supports)
 *   U bolts (optional)
 *   4.2 m of 1 cm (3/8 ") soft copper pipe (plumbing supply)
 *   4 sq. m wire mesh (hardware cloth at hardware store)
 *   2.5 m twin lead antenna cable
 *   portable radio with short wave band (SW 2)
 *   assorted nails, screws and staples

[http://www.jupiterradio.com/antenna/Antenna.gif]

 1.  Nail together the 183 cm square base.
 2.  Nail on the 5 upright supports.
 3.  Turn the base over and staple the screen to the bottom. The screen completely covers the bottom of the base. This screen is called the reflector.
 4.  Attach the antenna loop to the uprights with the U bolts. If you don't have U bolts, tie or wire the antenna loop in place. The distance from the wire mesh to the antenna loop is 68.6 cm.
 5.  Attach the twin lead antenna cable to the open ends or the antenna loop. You can do this by inserting the bare ends of the antenna cable into the open ends of the tube. Then, flatten the tube onto the wire with pliers, or use a large screw inserted into the ends of the tube.
 6.  Connect the other ends of the antenna wires to the radio. If your radio has a special place to connect an extra antenna, use that. If your radio just has a stick antenna, wrap 2 meters of insulated wire around the antenna. Attach the antenna cable to this wire.
 7.  Turn on the radio and select SW 2. Look closely at the numbers beside SW 2. They are 16 M to 49 M. Turn the volume up and tune towards the 16 M end of the dial. Your antenna will work best here.

[http://www.jupiterradio.com/antenna/short.gif]

 8.  Turn the tuning knob slowly as you listen. You should be hearing interesting sounds like hums, hisses and chirps, maybe even some foreign languages. You are detecting a variety of electromagnetic signals. Some might be coming from radio stations halfway around the world. Some could be secret codes from spies. Others will be signals from electrons stopping and going inside the machines close to you. Your refrigerator sends out signals and so does the transformer on a pole outside. But some of these sounds are signals arriving from planets and stars deep in space!
 9.  This antenna is designed to detect radio storms on Jupiter. You can check this out for yourself. First, find out where in the sky Jupiter appears. Then, tune the radio to a spot where nothing else is interfering. All you should hear is a steady, gentle hiss. Now, point the antenna at Jupiter and listen. If a radio storm is happening, you might hear something.

________________________________
CONNECTIONS

Many scientists believe that other intelligent forms exist in the universe. They are using enormous radio telescopes that are aimed into space. With these sensitive instruments, they listen constantly for electromagnetic signals. Perhaps there are aliens trying to communicate with us! They could be using electromagnetic signals like we do. We will never know unless we listen!

________________________________
CHALLENGE

 1.  Build a scale model of this antenna. Use cardboard, popsicle sticks, wire and your imagination.
 2.  Create a message that you would send out into space. Who might receive this message? How can you send it?

________________________________
FLASH FACT

Dave Hieserman wrote a book called Radio Astronomy for the Amateur. He says, "for the amateur radio astronomer, Jupiter is perhaps the most exciting and delightful radio source. Through a speaker, Jovian broadcasts are frequently reproduced as seashore sounds or very distinctive chirps or staccato noises." There are so many sources of electromagnetic signals that you might never be certain that you have heard Jupiter. But it sure is fun to try!

________________________________
TEACHER'S NOTES

This sophisticated project appears in the TAB book, Radio Astronomy for the Amateur. The antenna was designed by a university student as part of his work for his master's degree. The antenna was intended to detect electromagnetic signals from the planet, Jupiter.

All objects in space give off electromagnetic signals. Scientists who study these signals are called radio astronomers. Some astronomers are involved in a program called SETI, Search for Extra Terrestrial Intelligence. They are trying to detect signals from other intelligent life forms.

This is a difficult search. An endless array of signals comes from all over the universe and the distances are vast. Even though electromagnetic signals travel at the speed of light (299 791 km per second), it takes these signals years to travel from the closest stars outside our solar system. If astronomers detected a signal from a planet revolving around the star Betelgeuse and decided to send a signal back, it would take 1400 years to arrive! If a group of students decides to try this project, they can substitute some materials. Any metal pipe will do for the main loop. Any kind of metal screen will make a reflector. To "aim" the antenna, prop it up with the upright supports.

Many "ghetto blaster" type radios have shortwave bands. An amateur radio (HAM) Operator could help to interpret the sounds coming out of the radio.

Trying a project like this fires the imagination. It could trigger a lifelong interest in electronics and space. There certainly is a future in it.

For the interested:
Dave Hieserman
Radio Astronomy for the Astronomer
Tab Books, # 714

Roy L. Bishop
Observers Handbook
The Royal Astronomical Society Of Canada
136 Dupont St., Toronto
M5R IV2

The Young Astronomer
Usborne - Hayes
-------------- próxima parte ----------
Um anexo em HTML foi limpo...
URL: http://radio-amador.net/pipermail/cluster/attachments/20090506/ab3e6c1c/attachment.html