Think this will work?

[spongella]

Doesn't rain here very often, so had the idea to repurpose the umbrella as a reflector for a Ku "dish." No winds today so will try to see if I get a meter swing, if so, that is step one.

Think perhaps the surface of the umbrella needs to be lined with foil or something. The prototype is fully adjustable (except for the elevation angle) for azimuth, lnb angle, length, etc.

Might work better with one of those reflective umbrellas used in the photo industry.

Just looking for a meter swing first.....

Might make a dandy parabolic mike.

 

[fred555]

Off the top of my head I'm thinking the symmetrical shape would lend itself more to be prime focus.
It looks like you have it setup as an offset. I could be wrong.

 

[Magic Static]

There is a post somewhere here where all kinds of objects were used to reflect signal to a KU LNBF. They had picture on a snuff can lid

 

[. Raine]

I bet it will, once you line it with foil. If it don't work as an offset, try it as a prime focus like Fred said. Or try it both ways, see which works best! What's the diameter of it?

 

[fred555]

Take some measurements after you read this:

http://www.satsig.net/focal-length-parabolic-dish.htm

 

[spongella]

Thanks for all the comments guys. Will line it with aluminum foil first. Diameter is a little over 3 feet. Will try prime focus with a Ku LNB. Too small for any serious C band with the exception of maybe strong TPs on 99W.

 

[waylew]

Here ya go,


about 3:35 in.
omni quondo flunkus mortie

 

[N6BY]

Its big enough for KU, but I am guessing that the surface varies too much from a true parabola. According to the link in Fred's post #5: "For a receive only dish aim for maximum error of about 1/10th of a wavelength or about 6mm at C band and 2.5mm at Ku band."

Still very curious to know if it works.

 

[spongella]

That video is hilarious, he gets a signal from inside his house eh? Must have knocked a big hole in the roof for that to happen.

He needs to smooth out the wrinkles a bit otherwise he'll be getting right and left handed circular polarized transmissions......

Also saw one guy that made a guitar out of an old PPV dish, another made a nice lawn chair, one was using a C band dish as a fire pit, others a sled. What the human mind will conjure up!

 

[polgyver]

Still very curious to know if it works.

Seems it is not feasible...
Indeed, playing with ideas is better than mowing the grass or other chores
Maybe my umbrella is much smaller than that used by OP, as it has calculated and tried focal length = slightly above 7"
(and even the smallest pizza dishes have F = 10-11").
The mirrors were located at the best areas, half-way between the wires stretching the fabrics. Close to the wires, the fabrics would reflect sideways, thus useless for contributing to the focal spot.
Overall, the umbrella's "sphere" is too flat in the center, and too curved close to the edges - just the opposite of real paraboloid.
Eleven pictures follow :

 

[Claude Greiner]

I don't think the tin foil will work.

You may have better luck with metal tape they use for duct work.

 

[spongella]

There was an article published in TeleSatellite magazine years ago about a retired engineer in Japan who built a small portable umbrella dish, but his design was Cassegrain. The LNB was behind the umbrella.

http://www.tele-satellite.com/TELE-satellite-1007/eng/umbrella.pdf

Another one from a ham website:

http://www.qsl.net/kd6pag/AO-40/APRdish.html

 

[. Raine]

I think it could work, myself. It probably won't work as good as a regular dish, but that's to be expected, although sometimes the stuff surprises you! It's fun doing stuff like this and also I learn a lot trying out all sorts of different things like this. Interested to see what results you get from trying it!