[VHFcontesting] Sizing a horn for a dish

Sean Waite waisean at gmail.com
Fri Sep 28 22:25:32 EDT 2018

Hi all,

Now that I've (mostly) finished the rather significant process of cleaning
up my office and workbench and we've mostly settled into the "oh man there
are two kids now" lifestyle, I'm back to trying to get my 10 gig station

I have a small horn with an attached waveguide transition. The waveguide
appears from my novice measurements to be WR90 (it's about .9" wide), and
the horn flairs out to about 7.5cm x 5cm. The seller claimed it to be about
16dBi of gain.

I have an 18" TV dish that I hope to use. I've seen W1GHZ's documents on
using bits of string and such to properly aim an offset dish, but I have no
idea if this horn is of a size to acceptably illuminate the dish. If not,
no big deal I can still use the horn by itself for short contacts, or where
having a dish would be irritating.

Does anyone have pointers to documents showing how to size this? Is this
horn a usable size? I assume horn gain changes how close or far the horn is
to the dish.

It's a whole new world up in these bands, and info is scarce. Any help is

Sean WA1TE

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