CASPER
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Circular & Linear LNB's: What's the difference?
OK everyone, put your polarizing sunglasses on.
What's the difference?
Answer: About -3dB or half the signal level.
Now take your sunglasses off. Notice how bright it is in here? The
difference in brightness is an example of using the wrong lnb type.
Circular and Linear polarization refer to the characteristics of the
radio wave that is transmitted by the satellite towards your dish/LNB.
Below are links to visual comparisons of Circular (Left or Right-hand)
and Linear (Vertical or Horizontal) polarization.
Circular polarization refers to a wave of radio signal rotating in a
spiral. This spiral can be rotating in either the clockwise
("R"ight-hand) or counterclockwise ("L"eft-hand) direction. Think of an
approaching airplane as the plane's propellar is moving towards you.
The following example satellites (visable in N.America) are transmitting with a circular polarized signal:
EchoStar 3 @61.5°W EchoStar 3 at 61.5°W - LyngSat
EchoStar 8/10 @110.0°W DirecTV 5 & EchoStar 10/11 at 110.0°W - LyngSat
EchoStar 7 @119.0°W EchoStar 7 at 119.0°W - LyngSat
EchoStar 1/2 @148.0°W EchoStar 1/2 at 148.0°W - LyngSat
How do I know they are circularly polarized?
If you click on any one of the links for the satellites above you will
notice that under the first column labeled as "Freq. Tp" you will find
one of the following single letter designations:
"R" = right-hand (=circular polarization)
"L" = left-hand (=circular polarization)
So what about linear polarization?
Linear polarization refers to a wave of radio signal rotating in a
single plane. Think of an approaching helicopter as the helicopter's
main rotor is moving towards you. It is rotating in a single,
horizontal plane. The same approaching helicopter's smaller rear rotor
is rotating in a single, vertical plane. In our satellite case it can
be either in the "H"orizontal or "V"ertical plane.
The following example satellites (visable in N.America) are transmitting with a linear polarized signal:
SBS 6 @74.0°W SBS 6 at 80.9°W - LyngSat
AMC 5 @79.0°W AMC 5 at 79.0°W - LyngSat
AMC 9 @85.0°W AMC 9 at 83.0°W - LyngSat
IA 6 @93.0°W www.lyngsat.com/ia6.html
IA 5 @97.0°W www.lyngsat.com/ia5.html
AMC 1 @103.0°W AMC 1 at 103.0°W - LyngSat
AMC 2 at 105.0°W AMC 2 at 101.0°W - LyngSat
EchoStar 9 @121.0°W www.lyngsat.com/echo9ia13.html
Again, under the first column labeled as "Freq. Tp" you will find one of the following single letter designations:
"V" = vertical (=linear polarization)
"H" = horizontal (=linear polarization)
Now that you understand the difference between the two satellite
polarization types please put your polarizing sunglasses back on.
Hmmm, a little harder to read this right? Well, that's what happens to
your receiver when you try to use a linear polarized LNB to receive a
circular polarized satellite signal and vis-a-versa. About a 50% loss
of signal!
Armed with the invaluable information you now possess, by using this link North & South America - LyngSat you can determine for yourself what type of LNB you will need for each satellite.
If you need a circular polarized LNB look for words describing it as
"DSS" or "DBS" or "circular" or a combination of these terms.
If you need a linear polarized LNB look for words describing it as
"FSS" or "FTA" or "linear" or a combination of these terms (FYI: All
Universal LNB's are linear LNB's).
There are also LNB subtypes such as dual output or quad output. I won't
go into that here because there are several discusions on this forum as
well as a FAQ dealing with those subtypes. I suggest you use the
excellent search feature as well as spend some time reading the all
important "Sticky" threads.
OK everyone, put your polarizing sunglasses on.
What's the difference?
Answer: About -3dB or half the signal level.
Now take your sunglasses off. Notice how bright it is in here? The
difference in brightness is an example of using the wrong lnb type.
Circular and Linear polarization refer to the characteristics of the
radio wave that is transmitted by the satellite towards your dish/LNB.
Below are links to visual comparisons of Circular (Left or Right-hand)
and Linear (Vertical or Horizontal) polarization.
Circular polarization refers to a wave of radio signal rotating in a
spiral. This spiral can be rotating in either the clockwise
("R"ight-hand) or counterclockwise ("L"eft-hand) direction. Think of an
approaching airplane as the plane's propellar is moving towards you.
The following example satellites (visable in N.America) are transmitting with a circular polarized signal:
EchoStar 3 @61.5°W EchoStar 3 at 61.5°W - LyngSat
EchoStar 8/10 @110.0°W DirecTV 5 & EchoStar 10/11 at 110.0°W - LyngSat
EchoStar 7 @119.0°W EchoStar 7 at 119.0°W - LyngSat
EchoStar 1/2 @148.0°W EchoStar 1/2 at 148.0°W - LyngSat
How do I know they are circularly polarized?
If you click on any one of the links for the satellites above you will
notice that under the first column labeled as "Freq. Tp" you will find
one of the following single letter designations:
"R" = right-hand (=circular polarization)
"L" = left-hand (=circular polarization)
So what about linear polarization?
Linear polarization refers to a wave of radio signal rotating in a
single plane. Think of an approaching helicopter as the helicopter's
main rotor is moving towards you. It is rotating in a single,
horizontal plane. The same approaching helicopter's smaller rear rotor
is rotating in a single, vertical plane. In our satellite case it can
be either in the "H"orizontal or "V"ertical plane.
The following example satellites (visable in N.America) are transmitting with a linear polarized signal:
SBS 6 @74.0°W SBS 6 at 80.9°W - LyngSat
AMC 5 @79.0°W AMC 5 at 79.0°W - LyngSat
AMC 9 @85.0°W AMC 9 at 83.0°W - LyngSat
IA 6 @93.0°W www.lyngsat.com/ia6.html
IA 5 @97.0°W www.lyngsat.com/ia5.html
AMC 1 @103.0°W AMC 1 at 103.0°W - LyngSat
AMC 2 at 105.0°W AMC 2 at 101.0°W - LyngSat
EchoStar 9 @121.0°W www.lyngsat.com/echo9ia13.html
Again, under the first column labeled as "Freq. Tp" you will find one of the following single letter designations:
"V" = vertical (=linear polarization)
"H" = horizontal (=linear polarization)
Now that you understand the difference between the two satellite
polarization types please put your polarizing sunglasses back on.
Hmmm, a little harder to read this right? Well, that's what happens to
your receiver when you try to use a linear polarized LNB to receive a
circular polarized satellite signal and vis-a-versa. About a 50% loss
of signal!
Armed with the invaluable information you now possess, by using this link North & South America - LyngSat you can determine for yourself what type of LNB you will need for each satellite.
If you need a circular polarized LNB look for words describing it as
"DSS" or "DBS" or "circular" or a combination of these terms.
If you need a linear polarized LNB look for words describing it as
"FSS" or "FTA" or "linear" or a combination of these terms (FYI: All
Universal LNB's are linear LNB's).
There are also LNB subtypes such as dual output or quad output. I won't
go into that here because there are several discusions on this forum as
well as a FAQ dealing with those subtypes. I suggest you use the
excellent search feature as well as spend some time reading the all
important "Sticky" threads.