dissipointed cant get 10r!

[amc1]

The short answer is this -

The 1.8m dish has a very short focal length for its size.
The typical .9 m dish is quite a bit longer.

Most typical Ku band LNBF's are designed for a F/D ratio of 0.6 or 0.7 (0.6).
C-band dishes (this 1.8m is in that class) have a F/D around .3 or .4 (0.38).
So, for the LNBF to be able to "see" the entire surface of the dish...
... or to receive all the reflected energy right out to the edge...
...the LNBF needs to be more "wide angle" , in camera terms.

There's plenty more info available, and specs to quote, and all, but that's the bare tale.
And all the talk about LNBs being optimized for prime focus or offset-feed dishes, amounts to nothing more than their reception angle.

F/D is focal length of the dish, divided by diameter of the dish.

i was going to use astandard single lnbf 0.3db(typ).

 

[Anole]

That LNB would be looking at only the center portion of the dish.
And would be as though you had a smaller dish than 6 feet.


I bring this all up now, so you don't find out later and wonder...
...."why didn't anybody tell me?"

 

[amc1]

That LNB would be looking at only the center portion of the dish.
And would be as though you had a smaller dish than 6 feet.


I bring this all up now, so you don't find out later and wonder...
...."why didn't anybody tell me?"

what kind of lmbf would work for ku band ?

 

[Anole]

Note the hot links I made in post #18 and #20, above.
I even underlined them to stand out more.

 

[amc1]

Note the hot links I made in post #18 and #20, above.
I even underlined them to stand out more.

are you talking about the Invacom lmbf?can you explain alittle mor please on those lmbs ? seems there are few different 1's.there is a lot im only now learning about this stuff?