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Re: RE: Leo Class stations




>
>I'm currently am in the midst of experimenting with various LEO antenna 
>arrangements to expand my portable operation.  One idea that I currently 
>like is the idea
>of using a simple az-only TV rotator (available at RadioShack,etc for 
>~$60) to rotate a small vertical beam.  The beam is tilted upwards 
>slightly with respect to the horizon.  This provides good gain for the 
>lower elevation parts of the pass, and as the bird gets up higher its 
>increasing signal strength compensates for the beam's reduced sensitivity 
>at higher elevations.  The relatively low gain of the system makes 
>pointing requirements not all that stringent.

David, I've been doing this for years on the low orbit birds...You pick 
your combination of antennas, but the quadrifilar antennas provide 360° of 
~3db gain rotated in AZ only...see quadf5.jpg at

http://home.san.rr.com/doguimont/uploads

The quadrifilar construction is described in several other articles...easy 
to build and inexpensive...

I use it now on the surviving low orbit birds...



            73, Dave wb6llo@amsat.org
                    Disagree: I learn.... 


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