Anyone tried to make BIG dish at home?

[JanH]

Very nice clever idea!
Do you know what is difference between your designed shape and parabolic curve?

 

[fta-elite]

Thank you for your comments,

The antenna is made of aluminium and has the following measures:

diameter 187 Cm, Focus 72 cm, Depth 30 cm, f/d 0,37

I cut triangular segments of 100 cm long by 15 cm base

I used three rings with 31, 62, 93 cm radius

The shape is parabolic, but I do not use the equation of the parabola to calculate values (x, y) but to use the length of the parabola between two points x and x´

from center x=0 to x=31 cm the length is 31,2 ; x=31 to x= 62 is 32.7 and x=62 to x=93 is 35,4 cm

Regards,

 

[BombedOne]

Very interesting and nice

But weren't material costs higher, than factory made dish of such size?

 

[fta-elite]

In Colombia it is not easy to get an antenna of this size and it may cost some 600 dollars, I spent less than 100.

 

[mouse3]

Hi, fta-elite

Looks impressive your dish,but from the picture you make on the moonlight the focal point of the dish it s very large,beyound the feedhorn.20% of signal are lost.
You need to make this dish a cassegrain one,install the second reflector on the top for a better reception.Lots of professional dishes used for cassegrain one „V ” shape reflector.

 

[fta-elite]

You are right, mouse3, I had thought of making a cone (funnel) to avoid this loss of signal, but the idea of installing a second reflector is interesting.
Regards,
fta-elite

 

[driver]

hi all you do it yourself enthusiasts,

the focal length is one half the radius of the dish.

the cord that the dish represents can be divided centrally.

the angles can be calculated using trig.ie depth of cord length.

suppose two triangles within the cord.

extend to ,along radius, two larger triangles.

now you have a kite.four similar triangles.of equal angles.

the radius hence found, being the total length of the base off the larger

triangles + the hight of the smaller triangles.

the focus point is half this distance ,due to the divide by two action of the reflection from the tangent on the perimeter of the dish/cord

did you get that lol


cheers

 

[mouse3]

Hi,fta-elite
In the picture below you find the focal point under the sun.This shape it s wright ones.Must be small.Your s focal point must be like in the pictures.If the dish focal point it s very large you must add a second reflector to the dish.
Make the test under the sun or moonlight if it s warm autside under the sun when you make the adjustment and watch the results about focal point.After that install the LNC.


Hi,driver
The best way it s to make a test under the sun or monlight about the focal point.
This test it s the best becose not all dishes are good and have only one focal point,i found years ago one dish with two focal point 15 cm one next to other.Oval focal point.
For this reason owner of theat dish found only trouble watching on tv.Large dish with a small gain.


The Manage Attachments don t work,i don t know why.
Tommoro i try to upoad the picture for you.

 

[mouse3]

Pictures about a good focal point.

 

[JanH]

Be carefull to point your dish like mirror to sun. Could be very high temeperature in focal point. You can demage LNB or ....

 

[mouse3]

Early in the morning in the spring time the sun it s powerless,belive me,only looks like a furnace but the surface it s cold.

 

[gatojojoi]

Thank you for your comments,

The antenna is made of aluminium and has the following measures:

diameter 187 Cm, Focus 72 cm, Depth 30 cm, f/d 0,37

I cut triangular segments of 100 cm long by 15 cm base

I used three rings with 31, 62, 93 cm radius

The shape is parabolic, but I do not use the equation of the parabola to calculate values (x, y) but to use the length of the parabola between two points x and x´

from center x=0 to x=31 cm the length is 31,2 ; x=31 to x= 62 is 32.7 and x=62 to x=93 is 35,4 cm

Regards,

I am glad to see someone from Colombia doing this type of project. I travel a lot to Colombia and I have a Casa-Fica in Turbaco, Bolivar near Cartagena de Indias. I also have build dishes before but in fiberglass up to 12 feet diameter, but this was in 1980 when C band was the way to go. I have been contacting people in Colombia about dishes but as you mentioned, is hard to get your hands on one and then pay good $$$. My wish is to capture Echo14 at 119 West. I believe I need at least a 12' size dish or perhaps higher. I have been reported that with a 12' mesh you can get only 30% quality which is not very good. If there is any way we can get in contact, let me know. I will probably be traveling again to Colombia in May.

 

[fta-elite]

Hi Gatojojoi,
You have a part of the paradise in Colombia!!!.
With this dish I have captured the NSS-860, SatMex 5, SatMex6 and Intelsat 14 with a 50% quality, it is not so bad to be a home antenna, if you are in Cartagena I don't believe that you can capture the Echo 14, it requires at least one dish of 15'. To get in touch send me a PM.

See you

 

[Satcom1]

fta-elite

very nice construction, something to be proud of. Should give you many good years of service. Have you thought about adding a Ku LNBF to see if you will get anything?

 

[fta-elite]

Hi, Satcom1,
Yes, I did the test with a Ku LNB and the Satmex 5, this satellite has a few tps in ku-band and I got nothing, I'm going to keep trying with other satellites, it might not work for ku band as say it PaulR and Vipersan

 

[slugworth]

My wish is to capture Echo14 at 119 West.

119west is conus,so it would be way out of range.
Nagra3 anyway,unless you have an iks receiver that works.

 

[fta-elite]

It works in Ku Band!!! with 35% quality, here some pics from SatMex6:

 

[JanH]

Nice!
Can you roughly compare signal quality with other Ku band antenna?
What about raw aluminium plate thickness? Looks very slim.

 

[fta-elite]

Hi JanH, Let me this weekend do this comparison; the aluminun plate is 0.4mm.

 

[fta-elite]

OK, I did the test,

Receiver: SonicView 360 Elite
LNB: Universal, same kind, same brand
Satellite: Amazonaz at 61w

TP........................ Factory Dish 90cm.. Vs.. homemade Dish 180 cm

11888 H 28888 3/4.......... 80% .........................58%
11930 H 28888 3/4.......... 34% .........................47%
11767 H 28888 3/4.......... 53% .........................49%
12012 H 28888 3/4.......... 85% .........................78%

Blind scan .......................390 ...........................290 channels

Is difficult to make an accurate comparison, because it is impossible (for me) to adjust, polarization, elevation, azimuth, focus, etc...of two antennas equal at 100%.

fta-elite