Does the size of the satellite dish matter and if so why?
- Geoff SLv 61 decade agoFavorite Answer
Yes. This largely depends on what satellite TV service you have. For DBS services like DirecTV or Dish Network in the States, or Bell ExpressVu in Canada, Sky Dish in the UK, the minimal acceptable size is 18 inches. This will get you a signal 99% of the time regardless of weather conditions. 18" is actually quite small for a satellite dish and this is why they're typically referred to as minidishes. DBS services can get away with such small dishes because their satellites are amongst the highest powered, and also because of how far apart in the sky they are spaced. DBS services operate in the Ku band which is unfortunately susceptible to attenuation (signal deterioration) due to atmospheric precipitation, usually in the form of heavy rainfall. This is called rain fade. The bigger the dish, the more signal you will pull in, thus the less rain fade you will experience.
Other satellites in the Ku band which are not DBS vary greatly in output power. The minimum size dish recommended for these satellites is 30 inches. These satellites are also affected by rain fade so the bigger the better. Some transponders (typically digital) are still too weak to be picked up by a 30 inch dish and will require larger. If you are on the edge of a footprint, you'll have to have a bigger dish to pull in a watchable signal. Also, Ku band satellites can be spaced as tightly as a 2 degree difference in orbital slots. Compare this to 9 degrees in DBS satellites. What this means is that if your dish is too small, it sees too large of an area of the sky at one time and since satellites reuse the same frequencies from one satellite to another, you could pick up two satellites at one time and they'd interfere with each other.
Of the largest satellite dishes for consumer television use would be C band satellite dishes. These are known as BUD's or Big Ugly Dishes. The very minimum you could use is about 4 FEET in diameter, although 6' would be better and many consider 8' to be the minimum due to satellite spacing in some areas. These dishes also come in 10 and 12 feet for better reception. The reason why these dishes are so large is weaker satellites, satellite spacing but also because the frequency is much lower than Ku, the wavelengths are larger and a larger dish is needed to exhibit the amount of gain needed to provide a watchable signal. The C band does not experience rain fade. There is some attenuation but it is so little that it is never noticed.
All this is given that a uniform LNB is used between all the examples. Of course if you use some LNB with a rubbish noise figure you're going to get rubbish results. The sensitivity is with your receiver. The LNB is nothing but a block frequency converter with an amplifier, hence the name, Low Noise Block. The most important thing in LNB consideration is noise figure. You can have all the amplification in the world but if it is just amplifying locally generated noise, it's going to ruin your signal to noise ratio and it won't do you a bit of good at all. For Ku LNB's this is rated in dB. 0.3dB is considered excellent these days and 0.6dB is pretty average. Some manufacturers like to doctor these numbers up by various measuring techniques so if you see a low cost 0.2dB LNB, take it with a grain of salt. For C band LNB's, this is measured in noise temperature given in Kelvin. 15K these days is pretty good.
- Anonymous5 years ago
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I've been working for Dish Network for almost 3 years. The size of the dish has no real bearing on the strength of the singal you can get, although some dishes do have an easier time getting certain channels (ie international or HD). The only time you really need a lgiant dish is if yo live in puerto rico, hawaii, or alaska. As long as you have tiehr dish or direct, the normal sized dish will be fine. as far as the probvlems your having, it sounds like your LNBF(the "eyeball" of the dish) is going out. You can do whats called an LNBF reset(assumig you have dish). unplug all the receivers in your house, and disconect the cable going from the wall to the receivers, leave everything alone for about 5-10 minutes, then reconnect one of the boxes. let that oe boot up/load, then re-connect the other receivers. If you're still having the problem, cal your compnay, they'll probably have to send you out a new one
- Anonymous4 years ago
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- Master ULv 51 decade ago
The dish size will determine how much signal you have available for the LNB, the SENSITIVITY of the LNB will determine how much of that signal can be used.
So a large dish and a low gain LNB will only give you the same as a small dish with a High Gain LNB - BUT!! the signal to noise ratio (s/n) will be lower as the High Gain LNB will be amplifying more.
Best = Large Dish AND High Gain LNB
Oh and make that trackable so you can use other satellites too
- Barkley HoundLv 71 decade ago
You have no choice. Dish and Divectv use different size dishes but their signals may be different.
Dish makes a strange shaped one that is able to pick up two satellites at the same time.