Size of holes in perforated alu dish

[patmos]

I am trying to refurbish a 12 ft dish (pic2). The mesh is missing from the panels. I want to use thin aluminium(alloy) sheet[ those used in printing industry as a film). My friend did it and it works ( see pic1). Can anyone give me the exact hole dimension and distance apart for a perforated alu dish.

 

[WyrTwister]

I am trying to refurbish a 12 ft dish (pic2). The mesh is missing from the panels. I want to use thin aluminium(alloy) sheet[ those used in printing industry as a film). My friend did it and it works ( see pic1). Can anyone give me the exact hole dimension and distance apart for a perforated alu dish.

You do not have to perforate the sheet metal . I think less than 1/4" if you wish to do Ku band ?

Think you can also use fine mesh hail screen / hardware cloth ?

Wyr

 

[patmos]

thank you for answer.

You do not have to perforate the sheet metal . I think less than 1/4" if you wish to do Ku band ?

There is cyclone here ( Mauritius). This is a must.

Think you can also use fine mesh hail screen / hardware cloth ?

I do not know the material you are speaking of. Provided it does not get rusted easily.

 

[lumpkin666]

thank you for answer.
There is cyclone here ( Mauritius). This is a must.

You should do some research on this subject. I've seen several references to the fact that at moderately high wind speeds, a mesh dish acts no different than a solid in regards to wind. Once you get above a certain windspeed threshold, the perf/mesh dishes capture the same "force" of the air movement regardless of the perfs. So, even though you may think that you're doing the right thing by perfing your aluminum, you're actually weakening the surface and making it more susceptable to physical damage, while actually potentially reducing your signal strength capacity.

 

[patmos]

You should do some research on this subject. I've seen several references to the fact that at moderately high wind speeds, a mesh dish acts no different than a solid in regards to wind. Once you get above a certain windspeed threshold, the perf/mesh dishes capture the same "force" of the air movement regardless of the perfs. So, even though you may think that you're doing the right thing by perfing your aluminum, you're actually weakening the surface and making it more susceptable to physical damage, while actually potentially reducing your signal strength capacity.

Thank you for the reply. This is food for thought. These alu sheets are indeed thin and they will make much noise in moderate wind. So the holes are good to prevent this. I am not sure if this will withstand a cyclone of 180 km/hrs. I'm just trying to make it work.

 

[JohnH]

The hole size shown in the picture is larger than recomended for good Ku reception, but the spacing is such that Ku reception should work quite well. (since the holes are far apart).

Look at specs on new dishes for mesh hole sizes currently in use. Again, realize these mesh dishes have holes which are quite close to each other.

 

[gabshere]

the dish pictured above only shows a c-band feedhorn are your plans for c & ku reception or c band only and is it a concern about the wind load on the dish?

if its for winds i would mount as low as possible and if its going to be a stationary dish maybe a wind block ( enclosure ) on the back side of the dish.

 

[Anole]

One of the suggestions above was to use metal window-screen material.
It's available in both cheap plastic/nylon/etc, and metal.
Check at your local Home Depot, Lowe's or other home building store for other metallic mesh material.
There's also a kind with a 1/4" square hole, which might work for C-band only.

As for re-using your free aluminum plates, if you think you really need to reduce wind loading . . .
- remember that you can leave out panels and the dish will still work.
- if you leave out every other panel, the dish should still perform quite well.
- the dish might be stronger with panels in every sector, but they don't need to be full length

Other than for bragging rights, and the fact that it was probably free, what's the attraction of a 12' dish?
High FEC C-band reception would be aided, but I don't know of any Ku band signals that would justify a dish that size.

... Mauritius ...

Oh, I remember you! How did the 1.2, 1.5, or 1.8 meter dish work out?
Pardon my suggestion you go to the local hardware store.
I just realized where you are and why you want a big dish.
Best of luck.

 

[patmos]

the dish pictured above only shows a c-band feedhorn are your plans for c & ku reception or c band only and is it a concern about the wind load on the dish?

if its for winds i would mount as low as possible and if its going to be a stationary dish maybe a wind block ( enclosure ) on the back side of the dish.

The holes issue as you guessed well is in relation to KU. To reply to Anole :

Oh, I remember you! How did the 1.2, 1.5, or 1.8 meter dish work out?

My 1.2 m is working fine on PAS 10 KU. though it is borderline levels. I get it almost 24/7 now but it depends on conditions that are difficult to explain. Rain is a major factor affecting it. So I was thinking that after experimenting with C on PAS 10 /Thaicom , I will try the KU on the big dish to see the improvement with regard to my 1.2 m. I want to learn how it behaves.we tried 1.80 prime focus and it is worse than my 1.2m. I could not get a 1.8 m offset here.

I don't know of any Ku band signals that would justify a dish that size.

remember I am out of footprint. a 2.4 m solid prime will do it but as Anole said it is free.

remember that you can leave out panels and the dish will still work.
- if you leave out every other panel, the dish should still perform quite well.

Would not the gain of the dish be reduced by this( less surface area)?