SatSig topic:

Convert C-band dish to Ku

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Sep 16^th, 2009 at 2:37pm

Guys,
I need to use a C-band 4.9m VertexRSI antenna on Ku-Band transmission (I do not want a dual feed, just Ku)
What exactly does the C-to-Ku Conversion kit have?
Other than changing the OMT assembly, is there anything else that I need to look pay attention to? Will I get any service degradation?

Sep 16^th, 2009 at 3:43pm

Contact these people:
https://www.gdsatcom.com/contacts.php for advice.

I think they will recommend a complete new feed, including a conical feed horn at one end and OMT/transmit reject filter at the other.

The rings and slots inside the conical horn need to be smaller and closer together.

The diameter of the feed horn aperture needs to be less so that the power distibution onto the subreflector is correct. A too large diameter horn will only illuminate the middle of the subreflector and thus the middle of the main dish, giving low gain.

If the shape if the subreflector (e.g. slight ripples near the middle) is such as to minimise C band frequency reflections back down the feed this will not work at Ku band.

In the worst case, you will also need a new subreflector.

Best regards, Eric.