----- 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