Help: Which and what kind of C-band LNB should I buy?

[Sohaib]

Hey guys I'm having a bit problem receiving C-band channels properly here in my area.

The common problem everyone here experiencing is the interference of WiMAX Internet towers. It's interrupting the satellite(C-band) signals and giving weak to almost no signals as most of you might already be knowing of the fact.

Previously I had 15?K C-band LNB installed and I replaced it with 50?K C-band LNB which did improved the signals quite alot but still I'm having problem with signals of some of the channels. My neighbour is using 100?K C-band LNB and having almost trouble free reception with very few occasional signal interruption.


So I was wondering if any of you could advise me on what kind of C-band LNB should I buy? Should it be 100?K one? Or is there any other stronger which bypasses the WiMAX signals? I heard 60?K LNBs are good as well but I don't have much technical knowledge about it so looking for some advise here.

 

[dfergie]

Welcome to SatelliteGuys! your post got hung up and I moved it to the C-Band Forum.

 

[Sohaib]

Thanks! Hope to get to some information and help from here

 

[FaT Air]

I'm really surprised they authorized wimax at 3.5Ghz, knowing the interference issue was real. (but then again, C band "satellite" is "secondary use" in a lot of countries.
If you know where the wimax tower is, you may have to put up a shield. A wall of metal screen between it and the dish. Block the wimax signal from the dish. Then, more shields may be required to block the remote bases also. I've read in other forums, that some have minimized wimax interference by using a Norsat LNB. Saying they have better "out of band" rejection. Also, if band coverage is not needed down to 3.4Ghz to use a standard 3.7-4.2 Ghz model instead of the "wideband" model. This sight may be of some help. Satellite Interference Reduction Group
Another site thread I've seen cover this issue is C-Band wiped out by wireless modem - Free to Air Satellite Forums (Asia Pacific) - Sponsored by aDigitaLife.com Audio Visual Suppliers
I'm so far out in rural, it will be a cold day when wimax arrives, so don't think I'll ever see it. BITD, some terrestrial microwave was around but that "dried up" fairly quickly.

 

[Babadem]

I'm really surprised they authorized wimax at 3.5Ghz, knowing the interference issue was real. (but then again, C band "satellite" is "secondary use" in a lot of countries.
If you know where the wimax tower is, you may have to put up a shield. A wall of metal screen between it and the dish. Block the wimax signal from the dish. Then, more shields may be required to block the remote bases also. I've read in other forums, that some have minimized wimax interference by using a Norsat LNB. Saying they have better "out of band" rejection. Also, if band coverage is not needed down to 3.4Ghz to use a standard 3.7-4.2 Ghz model instead of the "wideband" model. This sight may be of some help. Satellite Interference Reduction Group
Another site thread I've seen cover this issue is C-Band wiped out by wireless modem - Free to Air Satellite Forums (Asia Pacific) - Sponsored by aDigitaLife.com Audio Visual Suppliers
I'm so far out in rural, it will be a cold day when wimax arrives, so don't think I'll ever see it. BITD, some terrestrial microwave was around but that "dried up" fairly quickly.

Never knew such a problem even existed. It's amazing the information one can pickup from here.

 

[ken2400]

The 15K one sounds like it would be under 10 years old.
the 50K and 100K sound like they are from the late 80's early 90's?
The last time I saw these number they were on LNAs and came in two parts. One mounted on the dish and the other down the line?

So I have been looking at

DMX741 it is both C and Ku in one unit.
DMX211 It needs a rotor to go between H and V so a bit of a pain.

What size dish are you working on?
Thanks

 

[mikekohl]

Pay attention to the information found in the Australian link. Then find out exactly what frequencies are being using in KSA for WiMax. It could be that the older LNB might also pass only the frequencies from around 3700 to 4200 MHz. Many new units claim "wideband" reception, with frequencies passing from downlink between 3400 and 4200 MHz. This would potentially get you 300 MHz closer to trouble from interference from lower adjacent frequencies.
If this checks out, a newer LNB with narrower coverage range may be the least costly solution.
Otherwise you are looking at using buildings and artificial shields to keep the WiMax transmissions from hitting your feedhorn. I know from my experience in the Kingdom 20 years ago with in-band 4 GHZ microwave interference, that it is almost impossible to "hide" from some of these transmissions---so follow the above advice. Otherwise you could also consider more costly and sometimes not-so-effective filtering. Good luck!

 

[Sohaib]

Pay attention to the information found in the Australian link. Then find out exactly what frequencies are being using in KSA for WiMax. It could be that the older LNB might also pass only the frequencies from around 3700 to 4200 MHz. Many new units claim "wideband" reception, with frequencies passing from downlink between 3400 and 4200 MHz. This would potentially get you 300 MHz closer to trouble from interference from lower adjacent frequencies.
If this checks out, a newer LNB with narrower coverage range may be the least costly solution.
Otherwise you are looking at using buildings and artificial shields to keep the WiMax transmissions from hitting your feedhorn. I know from my experience in the Kingdom 20 years ago with in-band 4 GHZ microwave interference, that it is almost impossible to "hide" from some of these transmissions---so follow the above advice. Otherwise you could also consider more costly and sometimes not-so-effective filtering. Good luck!

Well from what I found is that the WiMAX here in KSA is used at 3.5 GHz and that satellite channels on C-band that I want to view and receive are in the range of 3.7 to 4.2 GHz (on Asiasat3s and Intelsat 10). The only thing that puzzles me is that I have these two satellite dishes and so does my neighbour and both of our dishes are pointing exactly to same satellites. He's having 100k LNBs without any reception problem at all. I know I'm not a very technical person regarding this manner but could it be because of the LNB he is using? Does it contain any filter? I really don't know. Our dishes are near by(on the roof of our apartment building) and none of us are having any shielding for the dishes. There are no obstruction infront or on the side of the dishes either. That's where my confusion lies.

 

[FaT Air]

Would they be interested in letting you use their LNB for a short test? Put it on your dish and see if the problem disappears? That would be the best "investigative" solution to determine if "that's IT". Then, if it works, order the identical unit for your system. It very well may incorporate a "better filter".