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Re: F/D cal of offset dish



I was about the suggest this program when Charlie beat me to the punch!
Most of these dishes have a similar characteristic:  They seem to offset
the beam by twenty two degrees.....why I don't know but this note is sent
as a ham rather than an engineer for the moment!  The F/D is then adjusted
to the point where the feed is JUST out of the field of the dish.  This is
a great compromise indeed.  You can best visualize this as a PART of a full
dish where the lower edge is slightly above the line between the feed and
the center of a full circular reflector.  For most purposes this will get
you to the 90 percent point and with a bit more effort all the way!
     Cliff K7RR


Jim Jerzycke wrote:
> 
> W1GHZ has a neat little DOS program you can download
> from his website that will do this for you.
> 73, Jim  KQ6EA
> --- Charles Heisler -K3VDB- <ceheisler@suscom.net>
> wrote:
> >       Can anyone tell me how to calculate the F/D Ratio
> > of a offset Dish
> > so that I can build a 10G feed for it. The original
> > feed was at a focal
> > length of ~44.4cm.
> > My dish is 66cm X 60.6cm and is 6.5cm deep. I don't
> > think the cal. for a
> > round dish is what I want to use.
> >
> >       TNX for any help
> >       Charlie..K3VDB
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