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polarisation problem

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salam
Ex Member


Dec 12th, 2008 at 1:43pm  
I can recieve H polarised  q-band signals from ABS (75 degree East) from Dhaka (90.23 degree east, 23.41 degree north)

but V polarised Q-band signals can not be recieved.

The signal contour just touches my neighbrhood. I use 6ft eliptical antenna. Please help
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USN - Retired
Ex Member


Reply #1 - Dec 12th, 2008 at 3:18pm  
Unusual footprints on that satellite. See http://www.lyngsat-maps.com/abs1.html

But I have to start by asking you to restate which band you're attempting to receive. I only see what appears to be C-band (A & B footprints) and Ku-band (north and south footprints). Ku-band polarization appears to be vertical-north/horizontal south.

If you in fact are talking about ABS1 Ku-band North, note the dish size chart to the right of the footprint diagram on http://www.lyngsat-maps.com/maps/abs1_north.html. A six foot dish (1.8m) may not be sufficient at 23 degrees north longitude.

Another possibility is that your LNB does not have a dual (polarization) output. You may simply have to rotate it 90 degrees to intercept vertical signals.

//greg//
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salam
Ex Member


Reply #2 - Dec 18th, 2008 at 3:15pm  
Thanks for ur attention & queries.

I know the web address  http://www.lyngsat-maps.com/abs1.html  and often try to receive weak signal available at my position.

I was mentioning Q - band which is synonyme to Ku-band.

I tried to rotate my LNB 90 degree, it does not help.

For ur kind notice that, Express AM2 (80 degree East) can be recieved from my position at Dhaka,Bangladesh) though it is far beyond the signal available area.

Should I try to rotate my 6' dish by 90 degree?

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USN - Retired
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Reply #3 - Dec 18th, 2008 at 6:01pm  
Generally accepted microwave bands:
L band       1 to 2 GHz
S band       2 to 4 GHz
C band       4 to 8 GHz
X band       8 to 12 GHz
Ku band       12 to 18 GHz
K band       18 to 26.5 GHz
Ka band       26.5 to 40 GHz
Q band       30 to 50 GHz
U band       40 to 60 GHz
V band       50 to 75 GHz
E band       60 to 90 GHz
W band       75 to 110 GHz
F band       90 to 140 GHz
D band       110 to 170 GHz (Hot)

Before attempting anything with the dish, you might want to check the signal from the indoor receiver that changes the LNB output from horizontal to vertical.

If the receiver is sending the correct control signals, suspect the LNB

//greg//
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