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[aprssig] APRS buoy - transmit power and antenna?

Robert Bruninga bruninga at usna.edu
Tue Sep 11 13:45:12 UTC 2007


> I'd opt for maximum antenna efficiency and use a 
> suitably matched halfwave whip.  These are sold 
> as a ground plane independant antenna or GPI.

Yep, that is what a J-pole is.

> > Assuming you're in the open ocean and only care 
> > about hitting a satellite, is the J-pole going 
> > to give you a suitable radiation pattern?  
> > Or would a 1/4 wave be better?

There is no easy way to get the needed groundplane for a 1/4
wave.  Whereas the Jpole slides up nicely inside a fully sealed
piece of PVC pipe.

> >>>     Looks like about 9-10 miles for a bouy to a 30'
> >>> station...ignoring any ducting of course. 





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