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Three 1-meter antennas = One 3-meter antenna?


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Hi,

I would like to build an amateur radiotelescope for SETI. I know I need at least a 3-meter antenna, but they seem to be too expensive.

Would I get the same results by using three 1-meter antennas? How would I connect them to make them work as a single one?

Thank you! Regards.

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I'm no expert, but i believe you can basically make a radio telescope with as much width as you want for a very reasonable price provided you understand the electronics and physics involved.

I believe you can do it, but I do not know enough to help you. You may need to pick up a few books, and the software you would need to process the information would likely have to be written by yourself.

However, creating a 3 meter antenna yourself (disregarding interferometry) might be doable. You'd need a material (depending on wavelength, a mesh or wire would do) to reflect the radio waves and would probably want to use a Ritchey–Chrétien design (or off-axis variant). It would likely be a fair undertaking either way.

I wish you the best of luck with your endeavor :)

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10 minutes ago, pipnina said:

I'm no expert, but i believe you can basically make a radio telescope with as much width as you want for a very reasonable price provided you understand the electronics and physics involved.

I believe you can do it, but I do not know enough to help you. You may need to pick up a few books, and the software you would need to process the information would likely have to be written by yourself.

However, creating a 3 meter antenna yourself (disregarding interferometry) might be doable. You'd need a material (depending on wavelength, a mesh or wire would do) to reflect the radio waves and would probably want to use a Ritchey–Chrétien design (or off-axis variant). It would likely be a fair undertaking either way.

I wish you the best of luck with your endeavor :)

Thanks!

Some people have also told me that I would need 9 1-meter antennas .

Regards.

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38 minutes ago, alpha015 said:

Some people have also told me that I would need 9 1-meter antennas .

I am no expert, but I believe it would be a matter of resolution versus light gathering. You could put 3 dishes in a triangle shape with 1 meter separating them, and you would have 3 times the resolution despite your dishes only having a total surface area less than that of a 2m single dish. However the signal you get is weaker as a result, and limits you to "brighter" targets.

9 1m dishes provide the same surface area (light gathering power) as a single 3 meter dish. (1mx3²)

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10 hours ago, alpha015 said:

Thanks!

Some people have also told me that I would need 9 1-meter antennas .

Regards.

A 1metre dish at 1400mhz will have an approx gain of 20db at 50% efficiency.
A 3 metre dish at the same frequency will be approx 30db.

For every doubling of the antennas the most extra gain is 2.5db presuming they can be fed, spaced and matched correctly.
In this case 16 dishes would be needed, a 3 metre dish is more practical imo provided you can mount and point it.

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On 3/24/2018 at 21:24, alpha015 said:

amateur radiotelescope for SETI. I know I need at least a 3-meter antenna,

As others have said, resolution can be synthesized, integrated power needs physical area.

to detect SETI needs neither ! SETI detection only needs coherence and being in the right place at the right time, and  good luck with that.

So, if you want to map the sky at a particular wavelength, depending on the chosen wavelength, corner reflectors, dipoles above ground planes, wire arrays etc&etc can be effective, tell me, I have mapped the milky way Inwards towards Sagittarius , easy. Outwards not so easy, quite weak not so many aliens there!. But BOTH doable at 144MHz with reasonably not too expensive low-noise masthead  front ends.

The worst place to look for SETI is at 21cm, all that noise from hydrogen ! mad!! One need To ask, if they want to be heard, where would they broadcast ?

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On 27/03/2018 at 04:02, SilverAstro said:

The worst place to look for SETI is at 21cm, all that noise from hydrogen ! mad!! One need To ask, if they want to be heard, where would they broadcast ?

Ha! The Emperor has no clothes! I thought I was the only person to have noticed that massive flaw in the whole SETI idea....

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