Small C-Band dishes. Technical Thread

[ferazar]

Hi All, 1st post

I was reading the 1.2m Adrew C-Band thread and I was very thrilled by the technical level of the posters, therefore I wanted to pose a question.

Me and a friend at the university were wandering about the technical implications of a 1.0m C-Band Rx Only service.

Lets assume a 40+ dbW contour, full xpndr operation, DVB-S2 w/ LDPC, adjacent satellites at Ku only ...
What issues, like lnb performance vs price equation, dish specs, receiver SNR performance, etc would have to be CAREFULLY considered so such a service can work?

any technical xp using small dishes on c-band?
best regards

[deepbluesky]

This board here gathers some small dish C-Band users but i would recommend you to take a look also here: _http://forum.dxtv.de/wbb/thread.php?threadid=1072
Most of it is in German but most of the members do speak English as well. A 1m dish in the C-Band can be seen as extremely small and only suitable for very very strong frequencies.

[pedro2000uk]

Originally Posted by ferazar Hi All, 1st post I was reading the 1.2m Adrew C-Band thread and I was very thrilled by the technical level of the posters, therefore I wanted to pose a question. Me and a friend at the university were wandering about the technical implications of a 1.0m C-Band Rx Only service. Lets assume a 40+ dbW contour, full xpndr operation, DVB-S2 w/ LDPC, adjacent satellites at Ku only ... What issues, like lnb performance vs price equation, dish specs, receiver SNR performance, etc would have to be CAREFULLY considered so such a service can work? any technical xp using small dishes on c-band? best regards

At 45 dbW on a 1m, C Band works with a decent stb & lnb but without a decent rain fade margin even including C Band's better persistence in rain/ cloud.

[BombedOne]

Everything depends on your coverage zone. For example, I'm picking up TP6 from Express AM1 (40E) using 60cm offset dish, with quite high level, enough to withstand any weather fluctuations.

[pedro2000uk]

Originally Posted by BombedOne Everything depends on your coverage zone. For example, I'm picking up TP6 from Express AM1 (40E) using 60cm offset dish, with quite high level, enough to withstand any weather fluctuations.

That's very good for a 60- you are right in the middle and Lyngsat give it 48dbW+ there but even so ... not sure who is in the UK on C Band at that level anymore..

What LNB is that BombedOne..

[Turok]

here in europe it is defently to small you have some channels on 8 west telecom
and yhamal on 49e,for 40.,5 west 1.20 m is minimum size sometimes signal strenth espasely in winter is stronger on various cband satelites!
because of cold temperatour outside!
in asia small cband dishes are very cheap,around 80 €,here in europe,no manufactor mades this dish,anymore!

kti has this size avalible in the past,when you import from asia ++ww.dynasat.com
is a good source

you can use 1 m mesh dish for kuband here,and in other reagions the situation is via versa!

[dx qwer]

Hello Turok,

Originally Posted by Turok here in europe it is defently to small you have some channels on 8 west telecom ...

oh Turok, can you tell me wich channels you can see on Telecom @8°W?

Best Regards
Edgar.

[BombedOne]

It is GOSPELL branded, forgot exact model, is being sold as twin pack - two lnb, two feedhorns (one big, one small) and sheet for joining them side by side for multifeed.

[IanW]

Hey Feraza,

Spot on. I guess the issue for a DTH (Direct-To-Home) service on C-Band is more about C/NI - the I (Interference) being the limiting element. Interference from;

Terrestrial sources on shared bands.
Adjacent or other off-axis satellites.

But if you choose a robust setting of DVB-S2 it is pretty good and highly immune to unwanted DVB-S and DVB-S2 sources.

Ideally, you'd develop a neat mechanical package for the antenna and feed. Maybe a lens or FPA (Flat Plate Array) antenna ? Nulls tuned to off-axis sources. Keep thinking.

IanW.

[YashaRussia]

Originally Posted by BombedOne Everything depends on your coverage zone. For example, I'm picking up TP6 from Express AM1 (40E) using 60cm offset dish, with quite high level, enough to withstand any weather fluctuations.

Hi, BombedOne, and everyone,

I am going to try receiving the Express AM1 40 degr. tp6 Radio Orphei and TV Kultura channels in C band in St.Petersburg, Russia. According to your report, 60 cm dish would be enough. We have enormous winds (I live on the sea side and the dish will be on the roof of a 22 store building), so I would try the perforated 90 cm dish made in Russia, St.Petersburg by Lans. Do you think this can work? I live on the 2-nd floor, so the distance of the cable would be about 90 m. Another question, as I will be using a combined C/Ku LNB, have you any experience with them? And could I receive on the stationary dish both 40 and 36 degr.? 40 C band and 36 Ku band. What satellite should the dish point to? I guess, the 36, as the Ku band is more sensitive to direction, but it might send a stronger signal to my region... The 40 degr. is far more important to me, I need to be sure of adequate reception. Thank everybody for their possible reply.

[IanW]

Hey Yasha,

I would keep it simple and separate. 2 antennas.

40E - C-Band only. A small (90cm) prime focus mesh (perforated metal reflector) with C-Band circular polarised feed. You can use a conventional linear C-Band LNB and prime-focus linear C-Band feedhorn, then add a Circular > Linear de-polarising teflon slab inserted into the feed throat.

36E - An 60cm / 80cm offset Ku-band with Ku-band universal LNB.

And a DiSEqC switch at the antennas. The 90m cable is not a problem, but you will need an 'in-line' L-Band (950MHz - 2100MHz) IF amplifier, ideally placed 45m down the co-axial cable, that is halfway.

You might like to test ALL the equipment on the ground, including the 90m of cable before going on the roof

Perhaps you can install the antennas so they are protected from the wind ?

Good luck,

IanW.

[gipras]

hi all

i'm in italy and i have a 1 meter dish with lnb "panorama"
these are the sat that i can receive,naturally not all tranponders
64 E 49E 40E 30E 5W 22W all in circular.i want try some linear in 37W
but i don't know the correct position of the skew of the lnb,the "ZERO"position.maybe someone can help me?

[Channel Hopper]

Originally Posted by gipras hi all i'm in italy and i have a 1 meter dish with lnb "panorama" these are the sat that i can receive,naturally not all tranponders 64 E 49E 40E 30E 5W 22W all in circular.i want try some linear in 37W but i don't know the correct position of the skew of the lnb,the "ZERO"position.maybe someone can help me?

The answer would be with a meter locked onto one of the linear polarised signals near the top of the arc.

You need to find the position that receives minimum signal on the opposite polarity, as this equates to the best signal to noise ratio on the others.

[superdirto]

as CH says set your skew for maximum signal the linear sat. skew is not needed for the
circular sats

[Satcom1]

Originally Posted by ferazar Hi All, 1st post I was reading the 1.2m Adrew C-Band thread and I was very thrilled by the technical level of the posters, therefore I wanted to pose a question. Me and a friend at the university were wandering about the technical implications of a 1.0m C-Band Rx Only service. Lets assume a 40+ dbW contour, full xpndr operation, DVB-S2 w/ LDPC, adjacent satellites at Ku only ... What issues, like lnb performance vs price equation, dish specs, receiver SNR performance, etc would have to be CAREFULLY considered so such a service can work? any technical xp using small dishes on c-band? best regards

A conical Scalar is a must on 1 Meter but on 1.2 Meter the Flat Scalar will do just find for most dishes. Edit: I make my own 1 meter Prime Focus dish that does not have the cross polarization problems or adjacent satellite issues that an offset has.

LNBF in the 13K spec. like the Panorama is OK.

You can make this Cone Scalar for improved performance.

[Turok]

Hello!
thanks for your input
i am also using the panorma lnb,the diameter of the lnb,is a little bit smaler then lnbs of other brands,to use the panorama on the av com feedhorn from austrialia it has to be modify a little bit,because the panorma lnb is smaler in size !

[superdirto]

A conical Scalar is a must on 1 Meter but on 1.2 Meter the Flat Scalar will do just find for most dishes.


I can confirm there is NO signal increase with the WS conical scalar ring instead of the flat prime focus scalar ring (panorama) on my CM 1.2

[Satcom1]

Originally Posted by Turok Hello! thanks for your input i am also using the panorma lnb,the diameter of the lnb,is a little bit smaler then lnbs of other brands,to use the panorama on the av com feedhorn from austrialia it has to be modify a little bit,because the panorma lnb is smaler in size !

I bought my Panorama C Band LNBF on Ebay from MXMart. It is a top performing LNBF. I now have two of them. $17.00 USD. I see that someone in Europe is selling them for close to $100.00 with local shipping.

I also like the BSC 421 C Band LNBF. They are hard to find in USA now.

By the way what happened to the topic starter. No replies.

[superdirto]

I bought my Panorama C Band LNBF on Ebay from MXMart

what was the noise figure on yours, mine also came from mxmart but is marked 17k even though advertised as 13k he says its a typo and the same as the 13k
??

[robbiemcd]

anyone from northern ireland got a c band set up ?

[Satcom1]

Originally Posted by superdirto I bought my Panorama C Band LNBF on Ebay from MXMart what was the noise figure on yours, mine also came from mxmart but is marked 17k even though advertised as 13k he says its a typo and the same as the 13k ??

Mine are both marked 13K. I trust the guy if that is what he said. He was good to do business with.

The L.O. stability is another important issue with LNBF's and the Panaroma is rock solid.

This seems to be a case of having a very good rf design engineer. The quality of performance is outstanding even though the mechanical is consumer grade.