Help Regarding Dish Set Up

See the details of hotbird -6, It is a few hundred kilometers from you, Since the EOF EIRP is more than 40DBW, ( We catch 40dbw footprint of ABS-1 south beam on 60 cm dish) , YOu should easily get this on your 6 ft dish,

hot6.jpg


hot7.jpg
 
Qb . Noise will be more generated in prime dish than offset dish .where full illumination of prime dish not flown to focal feed point ? Specially edge of the dish as well as center of the dish? Is it right ?
 
Hello .according to your profile .you are in belgaum .for studies. So you can not get c band dish with you is for limeted permissiable . So as QB . Said go for a ku dish to start with to learn to tune the dish.
 
vishvish said:
Qb . Noise will be more generated in prime dish than offset dish .where full illumination of prime dish not flown to focal feed point ? Specially edge of the dish as well as center of the dish? Is it right ?

Right for a mesh dish, As the feed looks down, it will be looking at the HOT earth which is a known emitter of various electromag waves,
But on a good solid dish, with a neat shape and efficient side-lob suppression , It wont make a difference, SInce the feed will look only at the dish and wont see the earth

Also A Solid prime focus dish is cheaper than a solid offset dish of he same size anyway.
 
quickboy said:
Right for a mesh dish, As the feed looks down, it will be looking at the HOT earth which is a known emitter of various electromag waves,
But on a good solid dish, with a neat shape and efficient side-lob suppression , It wont make a difference, SInce the feed will look only at the dish and wont see the earth

Also A Solid prime focus dish is cheaper than a solid offset dish of he same size anyway.

If Cband signal is being reflected from the dish, then how can earth noise below the dish can reach the feed if it matched properly with the dish?
 
amatan said:
quickboy said:
Right for a mesh dish, As the feed looks down, it will be looking at the HOT earth which is a known emitter of various electromag waves,
But on a good solid dish, with a neat shape and efficient side-lob suppression , It wont make a difference, SInce the feed will look only at the dish and wont see the earth

Also A Solid prime focus dish is cheaper than a solid offset dish of he same size anyway.

If Cband signal is being reflected from the dish, then how can earth noise below the dish can reach the feed if it matched properly with the dish?

EARTH THERMAL NOISE:- natural noise that is not related to system equipment. One thing to remember, the satellite dish itself receives random noise from the earth in addition to signals from space, this random noise is often called earth thermal noise. Earth noise is something we can not control and is generated by the same internal molecular motion of all matter as is the case in system electronics. Therefore, when the dish is at its peak (i.e. not looking at the ground - over the horizon) it is receiving less earth thermal noise than when it is positioned looking out on the horizon. Thus, lower end satellites will always show a weaker signal than higher arc satellites - all things being equal - because more earth noise is being received at the same time low end arc satellite signal is being received than when top of the arc satellites are being received. If your satellites of interest are on the low end of the arc and those satellites are delivering weaker signals to your system after your best efforts at tuning the dish, then you will require a larger diameter dish though installing the best rated LNB you can afford might overcome this. Note, a larger diameter dish will take in more thermal noise, of course, but the increased satellite signals it will gather are more significant than the increased thermal noise it will pick up. (Side lobes of a larger dish are smaller in comparison to its main lobe so a larger dish receives less per cent noise per signal as compared to a smaller dish and, as the chart indicates, consequently shows to receive less noise than a smaller dish so that a larger diameter satellite dish is the clue to overcoming weak signals from low end of the arc satellites.)

(source-geo-orbit)
 
vishvish said:
EARTH THERMAL NOISE:- natural noise that is not related to system equipment. One thing to remember, the satellite dish itself receives random noise from the earth in addition to signals from space, this random noise is often called earth thermal noise.

Bolding mine as I am quoting above and below. My question was as QB said mesh dish will pickup more noise of the earth as those noise will enter the dish from its back (through mesh holes). So I am asking if the mesh is reflecting the signal which comes from the satellite, then why wont it reflect back the earth noise on its back side?

I told this to make a point that mesh dish wont simply allow all the earth noise like he said.


quickboy said:
vishvish said:
Qb . Noise will be more generated in prime dish than offset dish .where full illumination of prime dish not flown to focal feed point ? Specially edge of the dish as well as center of the dish? Is it right ?

Right for a mesh dish, As the feed looks down, it will be looking at the HOT earth which is a known emitter of various electromag waves,
But on a good solid dish, with a neat shape and efficient side-lob suppression , It wont make a difference, SInce the feed will look only at the dish and wont see the earth
 
amatan said:
If Cband signal is being reflected from the dish, then how can earth noise below the dish can reach the feed if it matched properly with the dish?

C-band signal is reflected from the dish, But for Ku you need smaller size of mesh, Well the dish definitely reflects most of the interference from outside,(Well otherwise you will find it difficult to catch anything on mesh dish, clearly), But then it is not designed to reflect every Electromagnetic signal anyway,That is why I say a solid dish is better. It is a comparison, between solid dish and mesh, A solid dish will surely give you better gain and less interference in comparison with a mesh dish of the same size and quality
 
quickboy said:
C-band signal is reflected from the dish, But for Ku you need smaller size of mesh, Well the dish definitely reflects most of the interference from outside,(Well otherwise you will find it difficult to catch anything on mesh dish, clearly), But then it is not designed to reflect every Electromagnetic signal anyway,That is why I say a solid dish is better. It is a comparison, between solid dish and mesh, A solid dish will surely give you better gain and less interference in comparison with a mesh dish of the same size and quality

Solid dish will give 20% more gain compared to mesh in Cband. Ku band is totally different and as mesh holes are bigger it wont reflect Ku much.
 
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