Hypothetical LNBF Spacing Question

[fred555]

Lets say I had a custom made scalar that placed two Titanium C2PLLs as close as possible, maybe touching each other. On a 10 foot dish what would you think the minimum separation achievable would be?
2 degrees, 4 degrees?

 

[Lone Gunman]

Measure it! Go to a known location, say, your due south sat then stand a step ladder up in front of the dish with something, ie, stick fastened to the side that would to up right next to your LNBF. Then move one satellite AWAY from the stick and measure how far it went. Since you know the number of degrees between the two satellites you went to, you should be able to figure out how many inches it is per degree.

 

[richyrich]

Measure it! Go to a known location, say, your due south sat then stand a step ladder up in front of the dish with something, ie, stick fastened to the side that would to up right next to your LNBF. Then move one satellite AWAY from the stick and measure how far it went. Since you know the number of degrees between the two satellites you went to, you should be able to figure out how many inches it is per degree.

This measure also depends on if the 2 lnbf in question are perfectly parallel (or elevated using the lnbf both aim different) to each other. By angling the 2-lnbf set towards each other; or both pointed at center of dish; and on the horizontal; then they remove half of the angle (because they each aim "through or past" each other like they were center focused; but are on the same parallel (or even the 2 elevations) of the dish (keeps the part of the dish full dish).

I would like to say all you guys talk about is easy; if you can understand what you are asking. The dbs type of dish does use only parallel lnbf's of the horizontal; using only the dish to make the angles. If you use the lnbf to cut the angles in half; they gain some signal level by using the middle of the dish; each. The center of the dish with 2 lnbf; both receiving the full parabola/round the dishes middle is spaced between the 2-lnbf (center of dish is between the 2 lnbf; and they both aim at the middle; both skewed; and both satellites linear c band; full signals of each). At 2 degree's the scalar's need to be cut or removed to allow them to fit close; but each must be isolated using plastic; and cannot touch each others metals....except to the diseq sw and cable gnd. serving them. I figured this out because every time I was mounting a second lnbf; i would lock up the system if the 2 lnbf's were powered up at the same time when I placed the second lnbf. By using a diseq sw only; tand plastic holding the next isolated from the first; it worked (over a certain number of lnb's; or a small ground in the home (smaller than the dish is as a ground) needed special "isolation" the cable companies used on their dishes (lnb's cost 500 each; and isolator's cost 1-500 (and they were just plastic,,,! Let's just say the plastic was needed because you do not want the "i's" to mix together; you want them seperate.

 

[fred555]

My answer is two degrees.

 

[migold]

I have 2 LNBF's on my 10' mesh which are receiving 97 and 101 at 4 degrees apart. I have 2 LNBF's on my 8' dish which are receiving 99 and 105 at 6 degrees apart, as illustrated in my avatar. Later this spring, I plan to try for 95 in addition to the 99 and 105 on the 8' dish. I have tried to get 2 degrees with no success on C-Band, but that does not mean it is not possible...

 

[polgyver]

Tried it a few years ago, with Ku dishes.
http://www.satelliteguys.us/xen/threads/not-all-dishes-can-take-regular-lnbs-for-97w-and-101w.269781/
"Selectivity" of a dish depends solely on its focal length.
In that time I believed (wrongly) that focal length of an offset dish could be measured from its center to LNBF "face".
That's why I measured this distance from an "X" marked on the dish...
Only later I learned that it should be measured from the bottom edge of dish.
With prime focus dish, its focal length is obvious.
But, your quoted diameter of your dish doesn't say much - its focal length also depends on f/D ratio.
Next factor, would be the diameter of LNBF. If they "collide", other types could be used (Titanium probably still has some "bullet" type LNBFs in stock)
OK, now I see, you can get 2 degree spacing...
cheers, polgyver

 

[richyrich]

My answer is two degrees.
View attachment 106122

And, the holes diameter is for fitting lnbf w/o scalar (; does it also allow the angle to also offset to the middle of the dish across the elevation change, and cut the angle in half across horizontal (to make the dishes middle, or prime focal and middle distance length; at the same time; when the dish is not motored; at all. Then amc7+amc10+as many as you want; can be aimed and arrayed using this "hole" technology. It is used on James Bond film's; and now in peoples homes. The cable companies used these years ago (60'-70's). This principle was missing in DIRECtv and Dish Network technology from their beginning; and they do not use it today; as their dish antenna is designed to focus the signals to their lnbf assembly.

And skew is easily set to the "hole"; also. As well as elevation and east/west aim; all with the middle of the dish. I just do not use too many scalars; but the plastic stays on 10 or more lnbf array's; as so many signals are focused at one time; the lnbf's count too much of the others as noise if they are powered up. Plastic, the answer to everything. One at a time powered by DISEq 1.1/1.0 switches ONLY! A dish laying flat on the ground; horiz.; works this way; every day of the week; and never moves an inch. I play with the offset; and it shows me the pictures I aim; while I am working on "duck pond satellite tv in the USA is an FTA"...You can also mount any satellite dish upside down; and it works this way; or even sideways; and it works this way also. it is not in their directions, either.

how many lnbf you can array this way is dependent solely upon use of the middle of the dish; and how many shadows of any signals needed from the dish; can be avoided (and 2 degree sats aimed). This picture is not 3d; but shows just a few on a duck pond dish; layed flat on the ground looking straight up; compared to a pre-determined offset for aim.

 

[richyrich]

Yes, the 2 degree problem is very relevant in this as a hypothesis. So many have done their dish this way now; even a copper bowl will pick up all the satellites you want? When you want all the channel's available, at the highest quality the signals can be gathered at. And, the 2 LNBf's; the how many more will fit without shadowing too much. fred555, if a shadow occur's (all center focused lnbf's are a (scalar's add even more shadow to the dish), and the 8 foot dish in the mid-west is all that is needed; what does putting 2 lnbf's; angled only 1 degree towards each other do? It adds a little more shadow, because then there are 5-10 lnbf's across the angle the dish needs to move angle, if motored; and receives from angles point past each other too. The offset dish in the picture removes the shadows. The lnbf's all receive only the un-shadowed this way; the only shadows to the dish are the lnbf's throat's (if they are off the halo effective points even a little bit they make a shadow to the other satellite signals). This halo area the lnbf's mount to is at the same prime focal distance from the dish at all times (as every lnbf must receive from to "get the full satellite dignal; unlike a DBS dish; because when you measure the distance from the lnbf to the dish; using the angle the lnbf is pointing; it is different for each pointing at the dish; instead of them all pointing at the middle of the dish.

How many can be offset this way? As many as you can mount; from one horizon to the other there must be 50 satellites; then 50 lnbf's would equal 100 degree's swath 25 each side of the dish 2 degree's apart each is exactly that many. Just putting 5 together this way AT OFFSET; will challenge you however you want to do it; they must be staticly mounted; perfect signals; for each onto the dish to not shadow the dish (offset does this); then take the motor off the dish and make sure it does not move either; and use the dish at offset instead. It is a good challenge, however; and worthy of the 4000 dollar's worth of lnbf's and 1.0/1.1 switches; to accomplish it for the cable company; they will pay!

 

[richyrich]

And, one of the greatest tools for using offset only typed dishes that look like they are upside down; then the bracelets used and the covers of the lnbf's are plastic on all the dbs dishes; and on big dish; the offsetting bracket is plastic; and the dbs pictures are circular only typed ku bands; and linear typed usually have scalars to mount to the halo effectiveness of the dish they aim for (at offset is the halo effect). Is a laptop outside; isolated using raspberry pi2; for using a switch can use a dbs 18" dish for radar purposes instead; and offsets are placed onto the round parabolics of a large perfect 10' or a new china made flatter (low f/d) satellite dish; completely isolated from the reflector because that is what a "pick-up" device; or collector is (as is a lnbf being aimed using the middle of the dish offset for aim)! The closeness of the lnbf's to each other does not matter; it is if they are isolated from each others grounding plane (as the H/V L/R does); what band of the band they are really receiving as a reflection the dish provides only each placed perfect and skewered too; isolated will collect perfectly.

Free to Air Satellite TV in the USA; means Duck Pond Satellite TV in their Front yard; in disguise as the ducks and types they receive their signals from type look.

In the front yard of a home; this is also a wishing well when set at chest height; built inside a home; it can be made using a green room approach; or as a stream/pond when mounted horizontally down low. Clear view to satellites required!/