I need a weak circular signal

[equant]

I'm working on a new satellite project and need to find a weak circular signal to test with. Something available to North America (Arizona).

Thanks for any helpful suggestions.

Nathan

 

[updatelee]

you can usually find some spot beams on DN birds that are close to your area but not quite enough for good signal.

SatBeams - Satellite Coverage Maps - Sat Footprint Intelsat 10-02 (Intelsat 1002, Intelsat Alpha-2, Intelsat X-02) / Thor 3 / Thor 5 (Thor 2R)

should help you find one

 

[equant]

Ah, that's a great suggestion. Thanks for the help.

 

[GrumpyGuy]

Another option might be to artificially attenuate the signal from a strong beam with a physical obstruction of some sort - foliage, plastic, glass, a coarse metal lattice, etc. Not sure what you are up to, but there might some advantage in having the ability to vary the strength of the signal as you make adjustments to your creation.

 

[Anole]

depends on your goal:

Yea, I was thinking of a wet sock over the LNB...

But just as workable, would be an obstruction to the dish.
If you do go that way, make sure you don't just block one side or the top/bottom.
Try to do something that lowers the signal quality equally in all directions.
(just not anything metallic, which might give you false aiming)
Literally, a wet blanket over the dish?? -

Well, that would matter if you are trying to align to a weak signal.
If not, ya might go to a super small dish, or a cake pan, or just aim the LNB at the sky.

 

[GrumpyGuy]

Anole brings up some good points. After sleeping on it I decided to strike some of my suggestions.

I would stick to flat, solid, non-conductive, non-porous materials securely but temporarily fastened to the face of the LNB cover - e.g. plastic cut from discarded household items. Multiple layers of identical material could be used to provide whatever degree of attenuation needed.

 

[B.J.]

A piece of plywood used to give me about 50% reduction of signal if I remember right. I forget how thick the plywood was, but probably about 1/2".
The plywood has to be put right in front of the feedhorn. If you use a bigger piece further away from the dish, the signal is scattered enough to give more reduction of signal, but placed in front of the feed, scattering won't bother the signal, as there is no place to go but into the feed.

 

[equant]

Thanks for the additional thoughts.

I'm surprised plywood only reduced reception by 50%.

 

[B.J.]

Thanks for the additional thoughts.

I'm surprised plywood only reduced reception by 50%.

On second thought, the plywood may have been thinner than 1/2"
I guess the actual percentage reduction isn't that meaningful, it was just based on what some receiver said. I think I was using a DirectTV receiver's meter, and who knows what that % actually means.
I did the experiment because years ago in one of the old analog TVRO internet groups, someone had posted about putting a C-band dish in the attic of his house or garage, and getting reception through the roof. I later decided to do the experiment and find out whether it would work with a fixed Ku dish. I could still get a lock if the plywood was real close to the feed, but if the plywood was blocking the signal a couple feet in front of the dish, I lost lock, hence my scattering theory. I assume that it might depend on the type of plywood, and probably wouldn't work well if the plywood was wet. I think I've done a similar experiment with my hand too.
I think the tendency is for people to think that if you can see through something that rf will go through it (like plastic or glass windows), but in reality both glass and plywood are solids, it's just that glass happens to be transparent to visible light, but may not be transparent to other frequencies, and wood will have it's own spectrum and will have some frequencies to which it's transparent and other freqs that it blocks. Being a ham, I used to hold a hand held transciever near a window to get better reception to a distant repeater, but I soon found out that I got better reception through the wall than through the window.