[NLRS] 2.4GHz helix for AO-51 & Aurora

[Andrew T. Flowers, K0SM]

Dan Larson wrote:

>I am planning on building a 2.4G Helix for AO-51.
>
>I have few questions:
>
>1) RHCP or LHCP?
>  
>
Dan,

I can address one of these questions:

The satellite downlinks are RHCP by convention, so you need a RHCP 
antenna.  If you are using a dish reflector, that means your feed needs 
to be LHCP so that it is RHCP after the reflection.  AO-51's S-band 
downlink is linear, so it really won't matter too much for that.  I use 
a tin-can and some aluminum foil for an antenna.  It's linear, but it 
gets the job done for ao-51.  My guess is that it is in the ballpart of 
9dBi of gain or so with the CalAmp 130016 converters.  I use a vertical 
and 50w for the 2m uplink, which leaves my hands free to point the 
S-band antenna and correct for doppler.  It takes some practice, but 
it's good fun!

Here's a picture:

http://www.frontiernet.net/~aflowers/ebay/pics/ao51-setup.JPG

-Andy K0SM/2





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