Advice Needed C120 Dual Feed OMT With Internal Plate

[moonbase]

Hi,

Would anyone please be able to advise me on the role of an internal plate that is present in a C120 Dual Feed orthomode transducer (OMT)?

The OMT has a straight cylindrical waveguide with C120 flange at one end and the 1st LNB connection port at the other end. Inside this straight cylindrical section there is an 2cm long internal plate located near to the point where the OMT branches off to the 2nd Ku LNB connection port. The internal plate is not directly at the point where the OMT branches off to the 2nd LNB port but it is set slightly further back with just a slight overlap with the point that the OMT branches off.

Has the internal plate anything to do with enabling reception of circular polarisation or is it used to deflect signal around the curved branch of the OMT that goes to the 2nd LNB port? Or is there some other use?

Also, on one side of the curved section of the OMT that branches off to the 2nd LNB port there is an allen nut mounted on the flat surface. Can anyone please advise me what this is for? Is it to close the signal path to the 2nd LNB port so that the OMT can be used with a single LNB connected to the 1st LNB port? Or, is there some other use?

I have attached a few pictures below of the OMT and other parts it connects to.

Any advice most appreciated.
Possibly one for "Channel Hopper" ?

Rgds

 

[BM300]

I was using this on fixed Seavey feedhorn to to pick the circular polarization.
It had a separate LNB for each polarization.
No internal plate.



h**p://www.afcsat.com/jpg/sev_4p2.jpg