Anyone tried to make BIG dish at home?

[BombedOne]

Now I'm thinking how to do it. Links here not allowed, but when I click "Go advanced" and then on "attachments" icon, nothing happens, so how could I post it?

 

[T_G]

Now I'm thinking how to do it. Links here not allowed, but when I click "Go advanced" and then on "attachments" icon, nothing happens, so how could I post it?

You have to click on the "manage attachent" button, then a popup window opens (make sure you got popups enabled). Then you browse for the file, and press upload button. When it has finished uploading you press "submit reply". If you are not sure you can do some testing in the test forum.

If the file you choose is too large or a wrong type, you get an eerror message on top.

Try it out and let me know how it went

 

[BombedOne]

Hehe, works now. It was IE problem, did it with Opera now.

 

[BombedOne]

Here you can see varios manufacturing stages of that wooden dish, and also can see self made multi-focus offset dishes, which were made out of window blinds.

 

[divibi]

Here you can see varios manufacturing stages of that wooden dish, and also can see self made multi-focus offset dishes, which were made out of window blinds.

Thank you so much for the pictures. I really like the wooden dish. But how rreliable are the wooden dishes? I know that wood expands and shrinks. Is that an issue, especially in Siberia? With shipping costs you mentioned maybe you'd be better off building your own dishes.

 

[T_G]

AMAZING! Great pictures, if anyone else got some more of the same subject please post them. I really like them home made dishes!

 

[Topper]

Hehe, works now. It was IE problem, did it with Opera now.

The wood working involved in that is not small time. somebody has put a lot of time into that unless it has been produced on a cad to prototype machine. Nevertheless whatever and however it was made is still something to behold:-omg:-thumb1

 

[divibi]

Hi guys,

I have just found my old notes and I can tell you that for large KU band dishes a MILLIMETRE ACCURACY is categorically required, otherwise 'why even bother' -as the minutest of flaws will render your whole work useless and the project will end in disaster. I don't think a 240cm wooden dish could keep 1mm precision in all its dimensions, etc. I just don't know. So we live we learn; I stilll hold hopes for a super precise mould to make fibreglass dishes,though.

Also I am aware of 'spun aluminium' dishes that are said to be theorethically very accurate ( 1mm precise?) but I don't know the first thing about this process; does it involve metal smelting and furnaces. Could you spin aluminium in your back garden?

 

[BombedOne]

I'm not in Siberia

That guy is hobby plane modelist, so he has certain experience with wood processing, including making it weather resistant. No CAD controlled machinery used, he only used electric bandsaw, that's all.

divibi, you may not know, but a lot of people do at home parabolic reflectors for telescopes (of course not 2m, but 50-60cm), and they achieve micrometre accuracy, not mm

 

[T_G]

All I know is that my dish is not very good, i.e slightly warped because of the cheap and nasty brackets, but still I get relative good reception. If you are striving for pefection and trying to get weak signals, then pefection is needed. But you can also do it the way american car manufacurers used to do: Instead of cultivating a small sport engine they just added more volume...

It is absolutely possible to do accurate dishes from wood or concrete etc, just depends how much time you spend on it.

 

[pride21]

hi all pics of wooden dish i made a couple of years ago,i made it into four sections that could be bolted together.

 

[divibi]

If you are striving for pefection and trying to get weak signals, then pefection is needed. But you can also do it the way american car manufacurers used to do: Instead of cultivating a small sport engine they just added more volume...

Yes, perfection is needed, especially in KU band. In C-band you can get away with a lot of imprecision.

 

[divibi]

divibi, you may not know, but a lot of people do at home parabolic reflectors for telescopes (of course not 2m, but 50-60cm), and they achieve micrometre accuracy, not mm

Hi BombedOne,

Thanks very much for very good info. I didn't know about MICROMETRE accuracy that they achieve. Do they use lasers to check the accuracy and wear magnifying glasses like watchmakers and jewellers? You've just given me hope it's possible to make a 1m dish that has the same gain as 1.80m one. Just imagine what dish gain those micrometres could give you!!!

 

[guest poster]

hi all pics of wooden dish i made a couple of years ago,i made it into four sections that could be bolted together.

Amazing... so how well did it actually do...?

 

[BombedOne]

Sorry, divibi, you misunderstood me. Micrometre precision is needed when dealing with waves, much much shorter than ones in Ku band (visible light), and regardless how well you polish your dish, antenna gain can't increase above certain level - which is directly related to dish size. So you'll have to do big dish in any cases.

 

[koansrc]

AMAZING! Great pictures, if anyone else got some more of the same subject please post them. I really like them home made dishes!

Here's my attempt. Not quite a "big dish" ...

http://www.satellites.co.uk/satellite/dish-setup-single-sat-multi-sat-motorised-systems/121715-aluminium-tin-foil-reflector-ku-band.html#post732855

and here's how :

http://www.satellites.co.uk/satelli...um-tin-foil-reflector-ku-band.html#post731602

 

[divibi]

The real problem is, book doesn't mentions quantity of fiberglass and epoxy needed even for 2 meter model (trough it says - 5 or 6 layers will be needed). So if it really needs large amount, maybe manufacturing will be expensive, than buying ready one. For test purposes, I bought 0.5kg of epoxy and 1x1m sheet of fiberglass fabric. This weekend I'll try to reproduce small scale (20-30cm) model, just to check manufacturing problem/expenses, I will not target parabolic shape, just will use beach ball as preform.

Hello,

Did you make that small scale model? Does it work and what do you estimate the costs to be for a 60 cm, 1m, 2m dishes? Thanks in advance.

 

[BombedOne]

No I still don't, too much work these days. But will do it asap.

 

[casser]

Nice to see a couple of homemade antennas..

what is the expected efficiency of those antennas?

I´m not a dish guy...i prefer waveguide antennas At this moment i´m testing a multibeam homemade antenna, but with 24dBi i´m only getting 18% of signal...i was expecting 40%

 

[Satcom1]

Hello Everyone, :-thumb1

This subject is of great interest to me. I found a little program that designs the parabola for you and is very easy to do "What If". You can match f/d to diameter and depth. It is called Parabola Calculator V 1.0 and you can Google it.
I was thinking of using a sand box and a screed board with the shape of the parabola. By using damp sand a very smooth surface is made. Once the surface was defined a Urethane plastisizer would be sprayed on with spray bottle. The Urethane hardens in contact with water. A layer of aluminum window screen is applied. Or, layers of fine woven glass cloth would build up. Once set hard and removed the back or mold side would be sanded smooth and Copper Leaf would be applied.

A sand mix concrete mixed somewhat dry could be used instead of the sand.

_http://www.educypedia.be/electronics/easoftrf.htm
This is the link for the parabola calculator.


I've attached a project report.