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Re: Dish surface 'flatness'



----- Original Message -----
From: "Peter Ellis" <vk1kep@gmail.com>
To: <amsat-bb@amsat.org>
Sent: Saturday, July 26, 2008 12:00 AM
Subject: [amsat-bb] Dish surface 'flatness'

> I am now the proud owner of a very 'second-hand' 3m mesh-covered
> skeleton dish.
>
> The mesh covering is metaphorical, rather than actual. I watched the
> dish on its back while as a group of small children rolled the dish back
> and forth and trampled holes in the mesh. That's the reason I was able
> to ask for it. "Please take it away," was the manager's reply to my query.
>
> Now, I need to re-mesh the dish, but I need to decide what 'flatness'
> ('true-ness') the surface should be. There has to be a formula, that
> encompasses things like: frequency of operation, curvature or focus
> distance, etc.
>
> I've done some looking online, but can't find it readily.
>
> Suggestions, and discussion, please?
>
> Please note: If you're going to also make product, brand name, or
> supplier suggestions, then be generic as suppliers and products in VK
> (Australia) will differ from where most list members will be sited.
>
> With thanks,
> Peter
> VK1KEP

Hi Peter, VK1KEP

To answere your question I have sent to you in two separate email the
TECHNICAL REPORT # 5 of the Crawford Hill VHF Club - W2NFA
with the following subject:

"A PARABOLOIDAL REFLECTOR ANTENNA FOR 1296 MHz"

This paper covers the following matter :

Basic Designe Considerations
Feed Antenna
The Parabolic Reflector - Error Tolerances
Surfacing Material
Paraboloidal Construction
Bandwidth
Radiation Pattern
Maximum Gain
Phase Center
Noise Temperature
Polarization

The above article is currently used by all EME'rs and was written with
the contribution of many authors of the Crawford Hill VHF Club - W2NFA

The article is 10 pages long and it was necessary to divide it into two
zipped files each about 2 MB long

If some other people is interested on it pleas let me know

Best 73" de

i8CVS Domenico




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