[NLRS] GHz project

[Jon Platt]

 Hi Kelley.   
I suggest that you read through the W1GHZ Microwave Antenna Book that is online at http://www.w1ghz.org/antbook/contents.htm   .  Chapter 6 is all about dish feeds and how they work.   Before tackling Chapter 6, read through Chapters 1 through 5 so that you have the "dish lingo" down before the discussions found in Chapter 6.   I think you will find what your looking for there.  There are some simple feeds that you can build described there (along with some more complex advanced ones too).
Let is know of any questions and good luck with the project !
73, JonW0ZQ
    On Monday, January 22, 2024 at 06:20:18 PM CST, Kelley <kelley at analogman.tech> wrote:  
 
 Sorry for the bandwidth if this is not appropriate for the list. I'm 
working on a simple project to begin understanding GHz signal 
transmission. I'm building a hydrogen line radio astronomy system. I 
picked this project as I pretty much have all the parts. However, I have 
a question concerning the antenna.

I have a 28" diameter dish antenna. It was at one time used in some kind 
of 5 GHz video system (or so I was told). The dish and mount are in 
excellent condition, but the feed fell apart due to age. I've determined 
that the focal point of this dish is a bit over 10".

However, it's not clear to me what I should put there to receive the 
1.42 GHz signal. The original feed point was a small circuit board with 
a trace that looked like a bracket [ placed on its side. All three sides 
were the same length (best I can tell as it's broken).

Can I just put a small dipole antenna, cut for 1/4 wave, at the focal 
point? I've seen on larger dishes that they put something like a can 
with a 1/4 wave dipole sticking through the side of the can at a certain 
point. This antenna doesn't seem large enough for that.

My goal here is to make something simple with the materials on hand and 
then move on to more sophisticated projects. I would appreciate any 
input or pointers to appropriate information.

Thanks,

Kelley - w0rk


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