Can I make my own dish? [Archive]

veryoldschool

06-29-07, 10:23 AM

Earl Bonovich

06-29-07, 10:26 AM

I am curious....

Why would you need a 6' dish?
Even in Florida the standard 5LNB (which is not 6') does work.

I am not sure it is just the reflector part (the metal piece), but you would also need the LNB assemblies, and work out all the angles and other items.

Making the dish, is just one step away from the "rocket science" parts of the SAT Reception equation.

veryoldschool

06-29-07, 10:31 AM

I am curious....Making the dish, is just one step away from the "rocket science" parts of the SAT Reception equation.
Not "rocket science" but close. It requires the "math" to make a deep space telescope by hand.

cygnusloop

06-29-07, 10:49 AM

Is it possible to make my own Directv dish? I own a manufacturing company and we make metal products. I can make just about anything in metal. Someone told me there is a special fiber in the dish? Can anyone help me here? I need a 6 foot dish where I live and the best price is $800! I'd rather build one!

Building a round single LNB dish designed to look at a single satellite position (101, for example) might be possible, if you have some good metrology equipment.

Building a 3 or 5 LNB dish will be much more difficult. They are asymmetrical, off-axis paraboloids, with very specific relationships between field of view and the size of the receiving area of the LNB.

It is not as simple as getting some plans for and existing DBS dish and scaling it up. You would also need to scale up the size of the LNB's as well.

I come at this problem as a optical engineer and telescope designer. There could be other subtleties that I am not aware of.

As far as the reflective surface of the dish goes, any old sheetmetal should look like a mirror to this frequency of radio light.

litzdog911

06-29-07, 10:51 AM

It's probably feasible to build your own dish to receive just DirecTV's main Ku-band 101-deg satellite with the appropriate materials, geometry and LNB. But building one to receive all of the main DirecTV satellites (101, 110 and 119-deg), plus the new Ka-band satellites at 99 & 103-deg W, would be a significant challenge. Keep us posted!

johnboul

06-29-07, 10:56 AM

I think I will try it anyway. My designer is precise and great with sheet metal working. Where can I get the angles I need and such?

Earl Bonovich

06-29-07, 11:06 AM

I think I will try it anyway. My designer is precise and great with sheet metal working. Where can I get the angles I need and such?

I don't know if they have been publicly published....

cygnusloop

06-29-07, 11:09 AM

I think I will try it anyway. My designer is precise and great with sheet metal working. Where can I get the angles I need and such?

No idea where to get "plans" other than measuring an existing dish, but for a single LNB dish you need to build an ~f/6 parabolic reflector and put the LNB at the focal point.

focal ratio= f = focal length of the dish/diameter of the dish

Good luck.

veryoldschool

06-29-07, 11:13 AM

I don't know if they have been publicly published....
Equations for defining a parabola in three dimensions.

cygnusloop
Want to look on your desk and post the title.

BTW: for those that are wondering, this dish is for use in very extreme latitudes either very high or low.

OrlandoJoe

06-29-07, 11:22 AM

I need a 6 foot dish where I live ...

Aside from the obvious distinction between needs and wants, I find the above statement curious. Are you referring to rain fade? The 5 LNB dish appears to be less susceptible to this that the old, smaller dishes. Does your HOA have a clause prohbiting DTV that you are trying to get around by disguising your dish?

cygnusloop

06-29-07, 11:36 AM

Equations for defining a parabola in three dimensions.

cygnusloop
Want to look on your desk and post the title.

BTW: for those that are wondering, this dish is for use in very extreme latitudes either very high or low.

The equation for a paraboloid (a 3D parabola) is easy:

(x/a)^2 + (y/b)^2 - z = 0

Everything you need to design a parabolic telescope (or dish) is in there. Deriving the parameters needed to design a physical part (requires much calculus), or defining what a, b, x, y, and z are in the real world is where it gets fun.

Personally, I use a fast computer and some very expensive software to do it.

cygnusloop

06-29-07, 11:38 AM

Aside from the obvious distinction between needs and wants, I find the above statement curious. Are you referring to rain fade? The 5 LNB dish appears to be less susceptible to this that the old, smaller dishes. Does your HOA have a clause prohbiting DTV that you are trying to get around by disguising your dish?

I would expect someone wants to take a receiver that "lives" in the US to some location at a more extreme latitude.

Don't ask, don't tell. It's just an academic discussion to me.

HarleyD

06-29-07, 11:41 AM

To echo what some of the others have hinted at, what has led you to decide you need a 6' dish? Were you told this by the same source that told you there were special fibers in the dish?

I ask because, like you and several of the posters in this thread, I am in Florida and I do just fine with the standard D* dishes in Central FL, as does my family in Naples at the extreme southern end of the state.

I just would hate to see you investing a lot of effort and some amount of money in pursuit of a false assumption.

boba

06-29-07, 12:06 PM

If you search posts Johnboul is South of the Rio Grande that is why he needs a 6' dish. If he has to ask the question about how to make a dish he pretty much has a SNOWBALLS CHANCE IN HE**. He has no knowledge of Spinning metal.

veryoldschool

06-29-07, 12:47 PM

If you search posts Johnboul is South of the Rio Grande that is why he needs a 6' dish. If he has to ask the question about how to make a dish he pretty much has a SOWBALLS CHANCE IN HE**. He has no knowledge of Spinning metal.
Now be nice.
If: "I own a manufacturing company and we make metal products." All he needs is someone that does know how on the payroll. It's nice to be the boss.
It may be a test to see how good that worker's skills are.
You just never know every thing now do you?
Being nice is better anyway. :)

premio

06-29-07, 12:53 PM

If you search posts Johnboul is South of the Rio Grande that is why he needs a 6' dish. If he has to ask the question about how to make a dish he pretty much has a SOWBALLS CHANCE IN HE**. He has no knowledge of Spinning metal.

A random question for those smarter than I. Is the wavelength from the satelites too big to do this? Or would you just need to ensure you had more smaller parts?

It seems you don't really need to spin metal to make it work. It really is the same theory as these reversed fresnel lens right used in the death ray below ?

Probably would want to use something that disperses IR instead of reflecting it though, or it may not last long :lol:

http://www.solardeathray.com/SDR_world.html

veryoldschool

06-29-07, 12:57 PM

A random question for those smarter than I. Is the wavelength from the satelites too big to do this? Or would you just need to ensure you had more smaller parts?

It seems you don't really need to spin metal to make it work It really is the same theory as these as a reversed fresnel lens right used in the death ray below.

Probably would want to use something that disperses IR instead of reflecting it though, or it may not last long :lol:

http://www.solardeathray.com/SDR_world.html
The higher the frequency, the more loss. The more water, the more loss in higher frequencies. The larger the "catcher's mitt" the more energy can be collected.

Whether it's "spun" or worked with an English wheel, it needs to follow a parabolic curve.

The higher the frequency, the shorter [smaller] the wavelength.

That link is like a Mythbuster's show [or was used on one I saw]. What [or why it's not done] would be the problem is all of the "space between" the small pieces, which would require a larger size than a solid reflector. Short of the increased size, "it should work" as the idea is correct.
EDIT: all of the "pieces" need to be the same distance from the focal point or there is a phase problem [hence the parabola].

johnboul

06-29-07, 01:34 PM

I don't get it? You just trying to be a smart a**?If you search posts Johnboul is South of the Rio Grande that is why he needs a 6' dish. If he has to ask the question about how to make a dish he pretty much has a SOWBALLS CHANCE IN HE**. He has no knowledge of Spinning metal.

johnboul

06-29-07, 01:42 PM

For one thing I am not south of Rio Grande or even close. Second, spinning metal is the least of my worries. Again, I manufacture metal products. From home goods to mechanical parts. I'm suprised you even know Rio Grande...hahahah

Anyways, enough fun with the kids. I will see what I can make. I just found out there is a place making dishes in metal. I am trying to get some info from them. I also saw one on a trip to the Dominican Republic.

veryoldschool

06-29-07, 01:46 PM

Anyways, enough fun with the kids. I will see what I can make. I just found out there is a place making dishes in metal. I am trying to get some info from them. I also saw one on a trip to the Dominican Republic.
"Most" southern copies are done in fiberglass [where the metal "special fiber" is needed].

johnboul

06-29-07, 01:50 PM

My other option is fiber glass...hhmmmmm It wasn't fiber, I just have no idea what its made of and a friend told me it has wires running through. I am just reading in now. Might be more difficult then I thought"Most" southern copies are done in fiberglass [where the metal "special fiber" is needed].

cygnusloop

06-29-07, 01:51 PM

A random question for those smarter than I. Is the wavelength from the satelites too big to do this? Or would you just need to ensure you had more smaller parts?

It seems you don't really need to spin metal to make it work. It really is the same theory as these reversed fresnel lens right used in the death ray below ?

Probably would want to use something that disperses IR instead of reflecting it though, or it may not last long :lol:

http://www.solardeathray.com/SDR_world.html

Sure, you could build something like that. But why would you want to in this application?

Astronomers build segmented mirror telescopes quite commonly now. And they do have an advantage. They increase your resolution, by artificially increasing the diameter of your telescope.

Angular resolution = wavelength/diameter

They will do nothing to increase your sensitivity, however, because the effective reflecting area does not increase.

Look at it this way. Say that you had a round 18 inch telescope mirror. It would have a certain resolution and sensitivity defined by the size of the mirror. If you took that mirror, and very carefully broke it into dozens of pieces, and laid them out to make a 36 inch diameter circle (being very careful to make sure all the pieces "point" at the focus), you would have a segmented mirror telescope. Referencing the above equation, this telescope would have the resolution of a 36 inch mirror, but the sensitivity of an 18 inch mirror. The diameter goes up by a factor of 2, and the angular resolution gets smaller (which means better resolution) by a factor of 2.

Resolution is typically not an issue when receiving satellite signals. Sensitivity is.

veryoldschool

06-29-07, 01:53 PM

My other option is fiber glass...hhmmmmm It wasn't fiber, I just have no idea what its made of and a friend told me it has wires running through. I am just reading in now. Might be more difficult then I thought
What you need is metal to reflect the signal. It can be foil, or fine mesh screen.

cygnusloop

06-29-07, 01:53 PM

My other option is fiber glass...hhmmmmm It wasn't fiber, I just have no idea what its made of and a friend told me it has wires running through. I am just reading in now. Might be more difficult then I thought

most likely the fiberglass would need some kind of wire mesh running through it for it to be an effective reflector. Without the mesh, radio light would just go straight through the dish, I think.

lwilli201

06-29-07, 02:07 PM

Would the dimensions of a C Band dish be close enough? Just a thought. :)

johnboul

06-29-07, 02:07 PM

I'm going to get a picture of the metal dish that work and post so all can see.

veryoldschool

06-29-07, 02:07 PM

davring

06-29-07, 02:09 PM

Years ago, before DSL, I subscribed to DirecPC. TV and Hi Speed Internet were on the same oval molded resin dish, close to the size of the Slimline. Talk about no rain rade, the 101 on a big dish. If there was any metalic particals in the resin I couldn't tell you, it was gun metal gray and I painted it terracotta red.

cygnusloop

06-29-07, 02:19 PM

Would the dimensions of a C Band dish be close enough? Just a thought. :)

Maybe. If you only want to see one satellite at a time. C-band dishes typically have small fields of view, and are designed to reject off axis signals. This can be a problem when trying to receive a constellation of satellites, such as the constellation at 101 degrees (people trying to use large dishes in Mexico often have this problem). Also, C-band uses a longer wavelength signal that Ka/Ku, so the mesh is typically larger on C-band dishes. IIRC, (it's been a while since I had a BUD) you could stick your pinky through the holes of the mesh on a C-band dish. This would leave you with the same problem of the signal going right through the dish, instead of reflecting.

aim2pls

06-29-07, 03:23 PM

he is the easy answer for building your own dish

1) back in the "ancient" days many metal companies tried building C'band dishes many did (good and bad) many failed (1/4" to play with on the parabolic)
2) back in the "old" C/KU-band days .... many of those failed (1/12" to play with)
3) and now KA (probably 1/32")

start with a case of beer ... drink the beer ... flatten the cans ... test ... failed >> get another case and repeat

johnboul

06-29-07, 03:38 PM

Just did my research. Building a dish is possible but I don't want to get into it. Just gonna buy one for now. I'll stick with the beer!

bobnielsen

06-29-07, 03:41 PM

most likely the fiberglass would need some kind of wire mesh running through it for it to be an effective reflector. Without the mesh, radio light would just go straight through the dish, I think.

Either that (Ka-band requires a fairly fine mesh) or a metallic coating.

bobnielsen

06-29-07, 03:43 PM

Would the dimensions of a C Band dish be close enough? Just a thought. :)

Size-wise probably. The accuracy (how close to a true parabola it is) and mesh size are more critical at the higher frequencies used for DBS.

aim2pls

06-29-07, 03:47 PM

most likely the fiberglass would need some kind of wire mesh running through it for it to be an effective reflector. Without the mesh, radio light would just go straight through the dish, I think.

usually most fiberglass (and plastic) dish manufacturers use aluminum screen.

I have actually seen a fiberglass dish without the mesh in it >> OOPS

morgantown

06-29-07, 04:32 PM

Just did my research. Building a dish is possible but I don't want to get into it. Just gonna buy one for now. I'll stick with the beer!

Now that sounds like a plan!

One option could be for you to only consider 99, 101, and 103. That would simplify things tremendously, especially if you are just looking for the vast majority of programming and where the HD will be.

All the same I'd place the order, get some (more) beer, and count the hours of time you saved :D.

premio

06-29-07, 04:49 PM

Now that sounds like a plan!

One option could be for you to only consider 99, 101, and 103. That would simplify things tremendously, especially if you are just looking for the vast majority of programming and where the HD will be.

All the same I'd place the order, get some (more) beer, and count the hours of time you saved :D.

Rats~

The Antenna guys building the DB12's from drying racks and coat hangers for pennies, wouldn't like this kind of timid nature.

I was intrigued to see someone do it with video on youtube.

cygnusloop

06-29-07, 05:52 PM

Rats~

The Antenna guys building the DB12's from drying racks and coat hangers for pennies, wouldn't like this kind of timid nature.

I was intrigued to see someone do it with video on youtube.

Yeah, I'd really like to see someone give it a try, just for the fun of it. A 2m class dish capable of getting the 101 would be a fun project for someone with the right skill set. Building a 3 LNB would get way too "fun" too fast.:nono:

HarleyD

06-29-07, 06:55 PM

Dang it! I still want to know why he can't use the standard issue dish.

P Smith

06-29-07, 07:22 PM

Whodo

06-29-07, 07:44 PM

johnboul
Sent you a PM.

cygnusloop

06-29-07, 08:22 PM

Speaking of capability regular ( parabola ) 1m offset Ku type dish.
I have in prime focus LNBF for 105W and from left to right 97W, 101W, 105W, 110W and 119W; signals not that high as for Phase III, but enough to get stable 70+ SS.

Good pointing is everything.

I wonder how far south you could go before everything besides 105 drops out with a 1m.:scratchin