Plywood Dish Antenna

[arshad07]

Hi Guys
i have made this dish with ply wood cutting it round measuring 4 ft
with lnb support with same measuremtn..

pls help me what is missing, what need to be changed...the dish is flat.....nd does not have a curvature.....

kindly help me....if this can be workable

 

[caddata]

dish is flat.....

Flat won't work. Flat reflects but does not focus.

A parabolic curve (used on all dishes both prime focus and offset focus) will focus all the reflected signal to a specific point. The unique feature of a parabolic curve (as opposed to spherical) is that all reflected signals arrive at the focal point in phase with eachother and combine to produce the highest gain. Anytime the parabolic surface varies from true, signals arrive at the focus slightly out of phase and subtract from those that are in phase, lowering the gain.

Harold

 

[PopcornNMore]

The wooden dish plans I have has wooden ribs that are cut and then plywood pizza shaped pieces get attached to the top. Aluminum or foil then gets attached to the plywood. Never had the time to build one.

 

[Andrewwski]

Hi Guys


pls help me what is missing, what need to be changed...the dish is flat.....nd does not have a curvature.....

That.

 

[hubba]

Here are my measurements it is 42 inch dish with a 4 inch depth. i used 1/2 plywood to build the ribs for the back. i marked the 48 inch wide part with a 1 1/2inch line from the edge to edge.( this is my zero line. everything get marked off this line.) if you look below you will see if you mark a center line in the middle of the 48 inches that would be your other zero line. Like X and Y points on a graft start marking from the center out to 21 inches on each side.


Linear Diam. 42.99
Diameter 42.00
Depth 04.00
Focal Length 27.56

x -21.00 y 4.00
x -19.69 y 3.52
x -18.38 y 3.06
x -17.06 y 2.64
x -15.75 y 2.25
x -14.44 y 1.89
x -13.13 y 1.56
x -11.81 y 1.27
x -10.50 y 1.00
x -9.19 y 0.77
x -7.88 y 0.56
x -6.56 y 0.39
x -5.25 y 0.25
x -3.94 y 0.14
x -2.63 y 0.06
x -1.31 y 0.02
x 0.00 y 0.00
x 1.31 y 0.02
x 2.63 y 0.06
x 3.94 y 0.14
x 5.25 y 0.25
x 6.56 y 0.39
x 7.88 y 0.56
x 9.19 y 0.77
x 10.50 y 1.00
x 11.81 y 1.27
x 13.13 y 1.56
x 14.44 y 1.89
x 15.75 y 2.25
x 17.06 y 2.64
x 18.38 y 3.06
x 19.69 y 3.52
x 21.00 y 4.00

 

[Corrado]

Since fiberglass dishes work well, I wonder if a coating over wood instead of screen or metal would work? Sounds like an interesting project.

 

[Wescopc]

Fiberglass must have a reflective material such as a metal screen embedded within it, the glass and resin alone won't do it.
Bob

 

[hubba]

In UK they were some clear dishs they were sell in over there. I think they might have something mixed in the plastic like lead to reflect

 

[hubba]

Here is a site that shows some of them.

h**p://www.satellitesuperstore.com/fixed-dishes.htm

 

[Sadie]

Here is a link to a forum dedicated to building home made dishes

75cm Ku band dish construction - Page 18 - Free to Air Satellite Forums (Asia Pacific)

Mine is on page 18 using mosi screen.
Start at the beginning of the thread, everything you need is there just allow a couple of hours to read it.

 

[Anole]

the Aussies did it quite well

Sadie has the answer.

And the same solution was offered in the last thread on this subject: Vetrun forum has the designs.
They've cornered the market, down there.

It's a long thread, but it's the best education you can get on the subject.
(Ya might skip over the Cuban guy toward the end, that should have been in its own thread)

I read it a couple of years ago, and gave serious thought to making one.
Then, I sobered up.