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Go Back   SailNet Community > On Board > Gear & Maintenance > Folding fabric satellite TV dish
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Thread: Folding fabric satellite TV dish Reply to Thread
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Topic Review (Newest First)
11-15-2012 01:16 AM
Frogwatch
Re: Folding fabric satellite TV dish

AS far as hot girls go, I'm a physics geek. I bore them and they bore me, no danger of me dressing any of them in shiny stuff.
11-15-2012 01:13 AM
Frogwatch
Re: Folding fabric satellite TV dish

Yes, I have done the numbers especially since weird optics is my occupation.
FIRST for Hellosailor. my fabric is more conductive than most metal dishes. Hence, for microwaves it is more reflective.
Figure accuracy is not much of an issue either. For a mirror to achieve best performance, its shape does not have to be better than 1/4 wavelength accuracy (Rayleigh proved it) and that means about 1/2" here. I will easily be better than 1/8 wavelength accurate.
When the fabric is taut, it is very strong and is held rigidly in the frame. It is not a wimpy umbrella-like frame. NASA used that for being lightweight, after all, no wind on the moon. Also notice its poor figure accuracy.
11-15-2012 12:19 AM
PaulinVictoria
Re: Folding fabric satellite TV dish

Quote:
Seriously, put your silver fabric on hot girl. That might be the best use of your overstock of silvery fabric, and free time.
How come my radar reflector doesn't look like that?
11-14-2012 03:27 PM
Barquito
Re: Folding fabric satellite TV dish

Personally, I think the "why not" questions need to be asked and answered. Usually, there is a good reason it is not done that way, but, you never know.
11-14-2012 07:36 AM
Navigator Wannabe
Re: Folding fabric satellite TV dish

Ah, same same, but different.

Again, the shape of the dish is essential to reflect the signal such that it is CONCENTRATED in the receiver.
And that thing is going to be much harder to keep in shape than the radar reflector. That's why it might work on the moon, but not here. We have atmosphere, and wind.

Seriously, put your silver fabric on hot girl. That might be the best use of your overstock of silvery fabric, and free time.



Quote:
Originally Posted by Frogwatch View Post
I had no idea sat TV dishes are so expensive, but then I dont even own a tv.
Of course looking at them on RVs and near boats gave me the idea of making them from the silver coated ripstop nylon. Unfold from a bag, pop it open, use the equitorial mount to align with N and the built in protractor to align azimuth and elevation.
When done, just fold it down again.
Whats the advantage? Not knowing anything about TV, I can sort of surmise that size equals signal strength and size is easy with this stuff.
On a boat or RV, you cant carry a big dish but with this you can.

Another way to do it would be to make the nylon airtight and put a rigid plastic cover over it (G10) and use about 1 psi air to inflate it (the nylon) to a near spherical shape. Use a longer focal length to get best approximation to a parabola.
11-11-2012 01:36 AM
hellosailor
Re: Folding fabric satellite TV dish

"There are even several patents fro collapsible fabric dishes but none on the market. "
From which we can conclude? Go ahead, make some guesses.

Do you have any idea how much signal loss/gain there is in a fabric parabolic dish, versus a metal or metal mesh dish? How much gain is actually needed fo what application? And how the lower gain from a fabric dish will require a BIGGER dish compared to solid metal?

Or, how well the metalized fabric will hold up, or degrade, after a year in harsh sun?

You don't have to run the numbers to get a patent, but you DO have to run the numbers before anyone is going to be interested in marketing it. And if the numbers come out wrong--itdoesn't even pay to spend money on a patent.

Have you run the numbers?
11-11-2012 12:32 AM
Frogwatch
Re: Folding fabric satellite TV dish

Being very aware of patents, I have seen those. However, I see none on the market. The patents are mostly expired. I think the inflatable one is a poor idea. There are even several patents fro collapsible fabric dishes but none on the market.
11-10-2012 08:23 PM
hellosailor
Re: Folding fabric satellite TV dish

bl, you're absolutely right. That was Buzz Aldrin's umbrella, it only looks upside down because the winds were so strong it inverted during a solar storm.

Froggie, give it up on the silvered cloths. If you inherited a boxload of silver lamé, sell it to some dancers or disco babes. Honest, that wheel has been invented before.
11-09-2012 11:52 PM
bljones
Re: Folding fabric satellite TV dish


that ain't neil armstrong's umbrella on the bow of the moon buggy
11-09-2012 11:46 PM
fallard
Re: Folding fabric satellite TV dish

The inflatable antenna has been done. See the patent at Patent US6963315 - Inflatable antenna - Google Patents, or check out the GATR corporate website (Home*-*GATR.com) for more info.
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