Proposed large dish discussion

[SeeMoreDigital]

The other day I read an article in a satellite magazine about a guy in Malta who wants to pick up signals from Astra 2 (28.2E). But did like the idea of installing an 3.0 - 3.5 meter dish... Well who would?

Anyway this got me thinking and I wondered if some of you guys might be able to shed some additional light with regards to the following couple of ideas: -

The multiple dish array system
Instead of using one massive 3.0 - 3.5 meter dish. How about installing several 0.6 meter dishes (well six in this case) and multiplexing them together.

As far as I can see, a simple 6-way 'F' combiner/splitter could be used to link all the dishes together, and should also provide the required polarity switching voltage to each LNB.

The only immediate problem I can see with the above idea is that the receiver might not be able to puke out enough voltage to run 6No LNB's... so ideas please?

The multiple output LNB system
Again instead of installing one massive 3.0 - 3.5 meter dish. How about installing one min 0.6 meter dish together with a multiple output LNB and multiplexing the outputs together, using the same method as the afore mentioned 'multiple dish array system' proposal.

Well, what do you guys think?


Cheers

[eb]

sorry SeeMoreDigital but I would rather prefer the solutions presented below

https://secure.olbort.com/images/CYBER1A.JPG
http://home.t-online.de/home/boettcher_satellitentechnik/wavefrontier_t90.htm

[SeeMoreDigital]

Hi eb,

The links you provided, look like they're 'single dish/multiple LNB' systems, with each LNB tracking a different satellite... is this correct?

If so it's not the same thing that I'm suggesting.


Cheers

[eb]

Hi SeeMoreDigital,

Yes you are right, from your proposals I am interestening if there is also rule as for short waves that let say 3 antenas in triangle with distance 4 meters/4km between them working as one with surface of this triangle, it seems to me that not /because of reflecting surface/ but maybe some gain can be achived.

eb

[SeeMoreDigital]

Yes, that's what I was thinking!

If the technique of linking multiple dishes together works for 'radio' astronomers, then it should also work for us satellite TV viewers :D


Cheers

[moon1234]

The reason radio astromers use multiple satellites is to eliminate interference. In order to obtain a higher gain you need one of the following:

1. Larger Antenna or better antenna design
2. More sensitive receiver (LNBf)
3. Amplifier

Number one is always the best alternative. That is why the Arecibo National Observatory is the largest dish in the world. Many little dishs tied together will still not receive a signal that is too weak for a single dish to receive. Not to mention that each dish will be slightly out of phase with the other dishes due to the length of the feed cable and other factors.

Number 2 will help, but it will also be much better at receiving terestrial interference as well.

Number 3 is usually a wash. You will amplify noise along with the weak signal. Amplifiers are best used to amplify an already strong signal. This would be used to transport the signal across a long cable run, redistribute through a multiplexed system, etc.

Your best option is always a larger dish.

-Moon1234

[SeeMoreDigital]

Originally posted by moon1234
Number one is always the best alternative. That is why the Arecibo National Observatory is the largest dish in the world. Many little dishs tied together will still not receive a signal that is too weak for a single dish to receive. Not to mention that each dish will be slightly out of phase with the other dishes due to the length of the feed cable and other factors. Hmmm!

So as long as a feint trace of a signal can be received, it might be possible to combine the signal.

And given that the signals are digital data streams (complete with error correction) surely the signals would still be in phase when combined?

It's just a thought!

[PlasMaBalL]

Always thought this would be fun to test but im pretty sure it isnt going to gain you anything due to the LNBs drifting in frequency and amplification differently then each other and completely destroying the combined signal.
I have no idea how exact the signals would be to combine right but your probably not going to get that from a consumer quality lnb.