how to make 6 feet c band dish?

[Vishal Panchal]

hi friends im trying to make 6 feet c +ku band dish plz tell me the detail calculations of it?like x y cordinate ,focal distanc ,depth plz

 

[neeraj26jan]

Hi Vishal,
Please download parabola calculator app on you PC and make your own dish. I am giving you the link of the software page. Please check "http://mscir.tripod.com/parabola/".

Thanks.

 

[Vishal Panchal]

i have downloaded it but it gives some error

 

[srinivas33]

Tell what error you are getting?

 

[Vishal Panchal]

actually i dont hav pc i downloaded it on cyber cafe pc it says update the something to do this you hav to reboot pc its windows i think its problem with library

 

[Vishal Panchal]

so plz if you hav this software give calculations and depth should be minimum so reflect area should increase

 

[srinivas33]

I will post the result of calculation from the parabola calculator for C band dish with the following parameters.

Diameter = 183 Cm
F/D Ratio = 0.38

Here F/D ratio is chosen with C band LNBF feed in mind, they are designed to see the entire dish with F/D ratio near to 0.32 to 0.44.

 

[srinivas33]

Linear Diam. 195.45
Diameter 183.00
Depth 30.10
Focal Length 69.54
Volume 395830.79
FLength/Diam 00.38
Area 26302.20

x -91.50 y 30.10
x -86.93 y 27.16
x -82.35 y 24.38
x -77.78 y 21.75
x -73.20 y 19.26
x -68.63 y 16.93
x -64.05 y 14.75
x -59.48 y 12.72
x -54.90 y 10.84
x -50.33 y 9.10
x -45.75 y 7.52
x -41.18 y 6.09
x -36.60 y 4.82
x -32.03 y 3.69
x -27.45 y 2.71
x -22.88 y 1.88
x -18.30 y 1.20
x -13.73 y 0.68
x -9.15 y 0.30
x -4.58 y 0.08
x 0.00 y 0.00
x 4.57 y 0.08
x 9.15 y 0.30
x 13.72 y 0.68
x 18.30 y 1.20
x 22.87 y 1.88
x 27.45 y 2.71
x 32.02 y 3.69
x 36.60 y 4.82
x 41.17 y 6.09
x 45.75 y 7.52
x 50.32 y 9.10
x 54.90 y 10.84
x 59.47 y 12.72
x 64.05 y 14.75
x 68.62 y 16.93
x 73.20 y 19.26
x 77.77 y 21.75
x 82.35 y 24.38
x 86.92 y 27.16
x 91.50 y 30.10

 

[srinivas33]

All units are in Cm

 

[srinivas33]

Making a C band dish is attempt able, as the tolerances in curve and mesh hole is about 1/10th of wavelength, which is about 7mm.

but making Ku band dish is difficult as the tolerance drops to about 2.5mm means we should not make error in curve bending not more than 2.5mm with Higher frequency nearly 12Ghz in mind. I made a 90cm ku band dish, I got very less signal for Insat 4b as i was not within tolerance.

but for C band it works, as we have almost 7 mm of excuse in surface accuracy. So we can make mistakes only in this 0 to 7mm, if you make mistakes more than this you will loose signal in C band also. So plot the curve on a large plywood sheet or large card board or anything rigid with a good small pointed marker. and fit your metal to the curve as accurate as possible.

further reference:
Ask Dr. SETI: Dish Surface Accuracy
Ask Dr. SETI: Dish Mesh Spacing
The SETI League, Inc.: Ask Dr. SETI