Re: [amsat-bb] I could hear AO40 :-)

["Frederick M. Spinner" <fspinner@xxxxxxxxxxx>]

>I then tested my dish and I figured out that it only gives 10dB extra gain.
>It is an 60cm dish, and when I am right it has to give 20dB (?)

A air-dielectric patch is about 8.5-10 dBi.  A 60 cm dish is like 21 dBi.  
10 dB difference is about right.  Keep this in mind for my next comment.

>
>So after many testings, I tried again to hear AO40 with only the patch
>because my dish was in the mast, and I could hear the beacon very weak!
>

>I tried the patch instead of the can feed, but it was only one S number
>extra.

If your S-unit is the standard 6 dB, then on a system that a "good signal" 
is 12-15 dB out of the noise, THIS IS SUBSTANTIAL.

>
>The problem is that I want to get ride of these terrible dish hehe.
>Its just to heavy to carry, and an umbrella dish is to fragile and would be
>physical to long. So I am looking for other antenna options with high gain
>and small size :-)
>

You've seen Bob Bruninga's portable "petal" dish?  This is an option.
I've also thought an array of air-dielectric patches might work, but it 
would require a lot of effort and probably a network analyzer to do it 
right. (you'd need an array of about eight to get in the same balpark as the 
60 cm dish.)  An other option, not one I personally like at microwave 
frequencies is to use an array of yagis or loop yagis.  Or a very large 
horn..  There are many different ways to make gain...

Fred W0FMS

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