What is the difference between L / R and Horizontal / Vertical Polarities ?

[al_madhi]

Hi . ppl regarding the above subject please clarify the differences in the polarities when comes to C-Band frequencies and Ku-Band frequencies . They use Vertical polarity ( V ) and Horizontal polarity ( H ) for Ku-Band frequencies While They use ( R ) polarity or ( L ) polarity for C-Band frequencies My question here what R or L stand for ? According to my humbled experice R stand for Right which means Vertiacl while L stand for Horizontal does that correct , If not Please Advice .

Best Regards

A.M.AL-MADHI

 

[PaulR]

If you can picture what horizontal and vertical are like then right and left can be visualised as H or V polarity rotating at one revolution per frequency. It can rotate either clockwise or anti-clockwise and these are known as right or left.

You can use an ordinary H/L type LNB to receive circularly polarised transmissions but there is a slight loss compared to using a dedicated R/L LNB. Obviously rotating an LNB for skew has no effect when receiving R/L transmissions.

 

[Vipersan]

Hi . ppl regarding the above subject please clarify the differences in the polarities when comes to C-Band frequencies and Ku-Band frequencies . They use Vertical polarity ( V ) and Horizontal polarity ( H ) for Ku-Band frequencies While They use ( R ) polarity or ( L ) polarity for C-Band frequencies My question here what R or L stand for ? According to my humbled experice R stand for Right which means Vertiacl while L stand for Horizontal does that correct , If not Please Advice .

Best Regards

A.M.AL-MADHI

H and V are the same in C band as they are in KU ..
Basical the signal is pre polarised Horizontaly or verticaly at the transponder ..so the positioning of the lnb skew wise is critical in order to maximise reception ..
L and R are in effect seen by an H/V lnb as the same signal ...and thus the lnb cannot differentiate ..ie ..seperate the 2 polarities ..
This requires mechanical or magnetic intervention at the lnb to de-polarise the circular signals ...effectively seperating or converting the signal into H and V ...
..the end product being a polarized signal which an H/V lnb can interpret ..
There are more complicated explanations ..requiring a knowledge of phase shift/vector diagrams ..

Here is a wiki link that should give you a rough idea whats going on ..
rgds
VS
_http://en.wikipedia.org/wiki/Circular_polarization

 

[Vipersan]

Just as a footnote ..

H doesn't directly equate to Left Circular ...as V doesn't to Right Circular ..
For convenience ..and for the sake of convention ...the placing of the depolarizing plate ..is positioned so that V equates to R and H equates to L ..
This doesn't have to be the case ...as newbies to C band often find out through trial and error ..
By inserting the depolarizing plate in the LNB 90 degrees shifted ...you can in effect reverse this convention ..and make L > V and R > H ..
rgds
VS

...to remember the convention in the early days ..I used to say to myself ...Stand up for what is right ....
ie ...Vertical is Right ...

 

[al_madhi]

Just as a footnote ..

H doesn't directly equate to Left Circular ...as V doesn't to Right Circular ..
For convenience ..and for the sake of convention ...the placing of the depolarizing plate ..is positioned so that V equates to R and H equates to L ..
This doesn't have to be the case ...as newbies to C band often find out through trial and error ..
By inserting the depolarizing plate in the LNB 90 degrees shifted ...you can in effect reverse this convention ..and make L > V and R > H ..
rgds
VS

...to remember the convention in the early days ..I used to say to myself ...Stand up for what is right ....
ie ...Vertical is Right ...

---------------------------------------------------------------------------------------------------------------
Thanks Vipersan for rspond and help

As you elaborated in your reply on Left and Right Circular ,Read this below regarding six polarities and explain

At the end of 2000 ( 22-7-2000 ) befor the Analog Transmission stops There were six polarites as follows :-

1-Right Circular Frequencies
2- Left Circular Frequencies
3- ( R ) Frequencies
4- ( L ) Frequencies
5- Horizontal Frequencies
6- Vertical Frequencies
All the above polarites are founded in Arabsat-2A during Analog Transmission
Which leads to another question What is the difference between Right Circular/ Left Circular and R /L which all circular

Best Regards

A.M.AL-MADHI

 

[Vipersan]

[/COLOR]---------------------------------------------------------------------------------------------------------------
Thanks Vipersan for rspond and help

As you elaborated in your reply on Left and Right Circular ,Read this below regarding six polarities and explain

At the end of 2000 ( 22-7-2000 ) befor the Analog Transmission stops There were six polarites as follows :-

1-Right Circular Frequencies
2- Left Circular Frequencies
3- ( R ) Frequencies
4- ( L ) Frequencies
5- Horizontal Frequencies
6- Vertical Frequencies
All the above polarites are founded in Arabsat-2A during Analog Transmission
Which leads to another question What is the difference between Right Circular/ Left Circular and R /L which all circular

Best Regards

A.M.AL-MADHI

There are only 4 basic polarities H = Horizontal ...V = Vertical ...(L) /LHC ...= left hand circular ...(R) /RHC = right hand circular ..

The difference between LHC and RHC ..

LHC corkscrews anticlockwise ...and RHC corkscrews the signal (polarity) .....Clockwise...and thats it ..
rgds
VS

 

[timo_w2s]

Just to add to this discussion, why don't we (Europeans) use circular polarisation any more for KU band? Wouldn't it eliminate any problems with skew, especially for motorised dishes? It's still used in Russia and North America isn't it?

 

[Vipersan]

Just to add to this discussion, why don't we (Europeans) use circular polarisation any more for KU band? Wouldn't it eliminate any problems with skew, especially for motorised dishes? It's still used in Russia and North America isn't it?

My guess ...
Cost of production of set top boxes ..and lnbs ..
Its cheaper and less hassle to produce an lnb with 2 probes built into the feed to detect the 2 linear polarities ..and the boxes don't then require any dielectric postitioning to detect the RHC and LHC ....as is done in a corotor ..
No moving parts ...simpler and cheaper to construct ..

Circular is known to be very efficient ...but is legacy stuff ..
It wouldn't exist in the commercial world of sat to home ...if back in the day ..they could have made linear lnbs at such a small cost as they do today...

Back in the days of BSB ...they did use it but was one circular polarity only ...
so less efficient use of the available spectrum ...
You can pack more into the same spectrum ..by alternating H and V..and without limiting yourself to RHC or LHC ..with no moving parts..

rgds
VS

 

[al_madhi]

Thanks Vipersan for respond and help again


There are only 4 basic polarities H = Horizontal ...V = Vertical ...(L) /LHC ...= left hand circular ...(R) /RHC = right hand circular ..

------------------------------------------------------------------------------------------------------------------
You mentioned above only 4 polarites , then what about the other two polarities ( R ) and ( L ) which they are using now

for Digital transmission for C-Band Frequencies And ( V ) Vertical and ( H ) Horizontal for Ku-Band Frequencies
Look at them at satellite position sites . RHC and LHC are now obsolete not to be used any more only they

were used during the Analog transmission , when we used to put a dielectric plate inside the neck of the C-Band Feedhorn to separate RHC and LHC

In Conclusion Only there are 4 polarities V / H for Ku-Frequencies and R / L for C-Band Frequencies



Only I am concerned about C-and Frequencies polarities R and L

Does R stand for Vertical and L stand for Horizontal or the other way round Please advice I confused

Best Regards

A.M. AL-MADHI

 

[Vipersan]

Thanks Vipersan for respond and help again


There are only 4 basic polarities H = Horizontal ...V = Vertical ...(L) /LHC ...= left hand circular ...(R) /RHC = right hand circular ..

------------------------------------------------------------------------------------------------------------------
You mentioned above only 4 polarites , then what about the other two polarities ( R ) and ( L ) which they are using now

for Digital transmission for C-Band Frequencies And ( V ) Vertical and ( H ) Horizontal for Ku-Band Frequencies
Look at them at satellite position sites . RHC and LHC are now obsolete not to be used any more only they

were used during the Analog transmission , when we used to put a dielectric plate inside the neck of the C-Band Feedhorn to separate RHC and LHC

In Conclusion Only there are 4 polarities V / H for Ku-Frequencies and R / L for C-Band Frequencies



Only I am concerned about C-and Frequencies polarities R and L

Does R stand for Vertical and L stand for Horizontal or the other way round Please advice I confused

Best Regards

A.M. AL-MADHI

I'm sorry if I wasn't clear enough ..
RHC and (R) are the same thing ..
R is just RHC abbreviated ....and the same applies the LHC = (L)

But strictly speaking R isn't V and L isn't H ...
Its just generally agreed that when the dielectric is inserted to depolarise (convert) circular to linear ...its done in such a way that R is depolarised to produce linear V ..and L is depolarised to produce H ....a generally accepted convention.
Sorry if you still don't understand ...but I can't make it any clearer.
rgds
VS

 

[al_madhi]

Its just generally agreed that when the dielectric is inserted to depolarise (convert) circular to linear ...its done in such a way that R is depolarised to produce linear V ..and L is depolarised to produce H ....a generally accepted convention.
--------------------------------------------------------------------------------------------------------------------

From your statement above You have answered my question

Which means

R = V and L = H

That is what I am after to find out Now you make it clear to me

Thank you very much

 

[Vipersan]

Its just generally agreed that when the dielectric is inserted to depolarise (convert) circular to linear ...its done in such a way that R is depolarised to produce linear V ..and L is depolarised to produce H ....a generally accepted convention.
--------------------------------------------------------------------------------------------------------------------

From your statement above You have answered my question

Which means

R = V and L = H

That is what I am after to find out Now you make it clear to me

Thank you very much

...Glad I could help ...
I hope you have success with whatever you are trying to set up ..
rgds
VS