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https://www.satsig.net/cgi-bin/yabb/YaBB.pl VSAT technology and installation >> Dish pointing and alignment >> polarisation problem https://www.satsig.net/cgi-bin/yabb/YaBB.pl?num=1229089429 Message started by salam on Dec 12^th, 2008 at 1:43pm

Title: polarisation problem
Post by salam on Dec 12^th, 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

Title: Re: polarisation problem
Post by USN - Retired on Dec 12^th, 2008 at 3:18pm

Unusual footprints on that satellite. See https://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 https://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//

Title: Re: polarisation problem
Post by salam on Dec 18^th, 2008 at 3:15pm

Thanks for ur attention & queries.

I know the web address �https://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?

Title: Re: polarisation problem
Post by USN - Retired on Dec 18^th, 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//