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 Determining appropriate dish sizes for satellites beams

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Drdanskills
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PostSubject: Determining appropriate dish sizes for satellites beams   2015-07-03, 18:35

How large a dish do I need for my desired satellite?

Practicalities

Before you determine how large a dish must be before you can receive a specific channel, there are a number of operational factors that need to be taken into account:

1. The make and efficiency of the dish – a solid dish will outperform a mesh dish of the same size. Similarly, a one-piece solid dish will be better than a segmented solid dish.
2. The quality of the LNB – the lower the noise figure (dB) and the smaller the local oscillator drift (KHz), the better the performance of the LNB. Note that some manufacturers only quote the best noise figures for their LNBs, rather than the average figure across the frequency band.
3. The design of the feedhorn – a mismatched feedhorn (or LNBF) and dish will impact detrimentally on performanc

4. The sensitivity of the receiver tuner – there can be a wide variation in the sensitivity of satellite receiver tuners. The tuners in PCI DVB-S cards, for example, are generally not very sensitive.
5. Weather – a Ku-band signal will be seriously attenuated by moisture. This is less important for lower frequency C-band transmissions.
6. Error correction – for digital transmissions, the lower the error correction, the larger the dish required to maintain a stable picture. For example, if you were able to receive signals with an FEC of 1/2 without any problems, signals with an FEC of 2/3 would require an antenna that is 1.3 times larger than the original antenna. Signals with an FEC of 3/4 means an antenna 1.4 times larger and with an FEC of 5/6 a factor of 1.5 is required.
7. Cable quality and length - poor quality cable or long runs of coax will impact on performance. A detailed analysis is provided here.


Theory
 
With the above points in mind, we can now look at interpreting footprint charts. These charts can be split into 3 types:
Global beam – 40% coverage of the earth’s surface. The signal strength degrades gradually as you move away from the focal point i.e. fringes.
Hemi beam – 20% coverage or one half of the hemisphere.
Zone/Spot beam – confined to a small area, but usually with high power output. The signal strength falls abruptly as you move away from the target zone.
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PostSubject: Re: Determining appropriate dish sizes for satellites beams   2015-07-03, 18:51

Based on the above information, we can now determine what is the minimum diameter dish required to receive a specific channel. Remember, however, that these values are only a guide and will vary depending on your actual system.

Ku-band EIRP values vs. dish diameter (LNB noise figure of 0.7dB) 
  EIRP     Size    EIRP    Size 
55dBW  40cm  43dBW  100cm 
54dBW  45cm  42dBW  110cm 
53dBW  50cm  41dBW  120cm 
52dBW  50cm  40dBW  120cm 
51dBW  55cm  39dBW  135cm 
50dBW  60cm  38dBW  150cm 
49dBW  65cm  37dBW  180cm 
48dBW  70cm  36dBW  240cm 
47dBW  75cm  35dBW  300cm 
46dBW  80cm  34dBW  355cm 
45dBW  90cm  33dBW  400cm 
44dBW  90cm  32dBW  450cm
Direct links to the satellite EIRP charts can be found at Lyngsat. Satbeams also provide EIRP charts in a single, standardised format.
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PostSubject: Re: Determining appropriate dish sizes for satellites beams   2015-07-03, 18:59

what is this pls???
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Drdanskills
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PostSubject: Re: Determining appropriate dish sizes for satellites beams   2015-07-03, 19:51

[You must be registered and logged in to see this link.] wrote:
what is this pls???
Have you read through?
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PostSubject: Re: Determining appropriate dish sizes for satellites beams   2015-07-03, 21:50

[You must be registered and logged in to see this link.] wrote:
How large a dish do I need for my desired satellite?

Practicalities

Before you determine how large a dish must be before you can receive a specific channel, there are a number of operational factors that need to be taken into account:

1. The make and efficiency of the dish – a solid dish will outperform a mesh dish of the same size. Similarly, a one-piece solid dish will be better than a segmented solid dish.
2. The quality of the LNB – the lower the noise figure (dB) and the smaller the local oscillator drift (KHz), the better the performance of the LNB. Note that some manufacturers only quote the best noise figures for their LNBs, rather than the average figure across the frequency band.
3. The design of the feedhorn – a mismatched feedhorn (or LNBF) and dish will impact detrimentally on performanc

4. The sensitivity of the receiver tuner – there can be a wide variation in the sensitivity of satellite receiver tuners. The tuners in PCI DVB-S cards, for example, are generally not very sensitive.
5. Weather – a Ku-band signal will be seriously attenuated by moisture. This is less important for lower frequency C-band transmissions.
6. Error correction – for digital transmissions, the lower the error correction, the larger the dish required to maintain a stable picture. For example, if you were able to receive signals with an FEC of 1/2 without any problems, signals with an FEC of 2/3 would require an antenna that is 1.3 times larger than the original antenna. Signals with an FEC of 3/4 means an antenna 1.4 times larger and with an FEC of 5/6 a factor of 1.5 is required.
7. Cable quality and length - poor quality cable or long runs of coax will impact on performance. A detailed analysis is provided here.


Theory
 
With the above points in mind, we can now look at interpreting footprint charts. These charts can be split into 3 types:
Global beam – 40% coverage of the earth’s surface. The signal strength degrades gradually as you move away from the focal point i.e. fringes.
Hemi beam – 20% coverage or one half of the hemisphere.
Zone/Spot beam – confined to a small area, but usually with high power output. The signal strength falls abruptly as you move away from the target zone.
Nice one Bro, this would help for us to determine the size and satellite it will nail.
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PostSubject: Re: Determining appropriate dish sizes for satellites beams   2015-07-03, 23:00

I think pro installers already got the drift. nice one pal !

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PostSubject: Re: Determining appropriate dish sizes for satellites beams   2015-07-13, 20:57

Thanks guys.
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PostSubject: Re: Determining appropriate dish sizes for satellites beams   2015-07-14, 07:49

NICELY
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PostSubject: Re: Determining appropriate dish sizes for satellites beams   2015-07-14, 14:19

Yeah
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PostSubject: Re: Determining appropriate dish sizes for satellites beams   2015-07-14, 18:57

[You must be registered and logged in to see this link.] wrote:
what is this pls???
u hav com here 2 disgrace ursef again ehn?
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PostSubject: Re: Determining appropriate dish sizes for satellites beams   2015-07-14, 18:59

[You must be registered and logged in to see this link.] wrote:
Thanks guys.
more grease 2 ya elbow jare baba Big-Dish. lol! buh I fink d stowy neva finish o
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PostSubject: Re: Determining appropriate dish sizes for satellites beams   2015-07-14, 19:04

Hmmm
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PostSubject: Re: Determining appropriate dish sizes for satellites beams   2015-07-15, 07:31

Idea
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PostSubject: Re: Determining appropriate dish sizes for satellites beams   2015-07-15, 14:09

GOOD
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PostSubject: Re: Determining appropriate dish sizes for satellites beams   2015-07-15, 15:04

STOP SUBSCRIBE DSTV IN NIGERIA
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PostSubject: Re: Determining appropriate dish sizes for satellites beams   2016-04-23, 13:39

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PostSubject: Re: Determining appropriate dish sizes for satellites beams   2016-04-23, 13:41

We have alot of teachers here
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PostSubject: Re: Determining appropriate dish sizes for satellites beams   2016-04-23, 14:30

Nice one
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PostSubject: Re: Determining appropriate dish sizes for satellites beams   2016-04-26, 21:22

Ok
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PostSubject: Re: Determining appropriate dish sizes for satellites beams   2016-04-27, 07:30

[You must be registered and logged in to see this link.] wrote:
what is this pls???
Limit of the dish and size
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PostSubject: Re: Determining appropriate dish sizes for satellites beams   2016-04-27, 15:11

Good.
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PostSubject: Re: Determining appropriate dish sizes for satellites beams   2016-05-05, 22:20

Still useful
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PostSubject: Re: Determining appropriate dish sizes for satellites beams   2016-05-06, 01:59

What is this visit that visit this,rubbish talk moderator do something ke
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PostSubject: Re: Determining appropriate dish sizes for satellites beams   2016-05-06, 07:17

Good
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PostSubject: Re: Determining appropriate dish sizes for satellites beams   2016-05-06, 15:01

Moderator monitor your site well
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