[amsat-bb] Re: Quadrifilar Helices
dguimon1 at san.rr.com
Fri Nov 2 09:33:09 PST 2007
>The Satellite Experimenters Handbook by Martin Davidoff K2UBC (1990 Pages
>8-15 & 16) and it's successor The Radio Amateur's Satellite Handbook (1998
>pages 10-13 to 10-15) both have details of this antenna, its use and its
>I recommend this book to all satellite experimenters and users, it may be
>nearly 10 years old but the principles and information contained therein
>have not changed.
>Robin Haighton VE3FRH
>Immediate Past President AMSAT
That's exactly where I started, Robin, on page 6-20 of the original edition.
But Maxwell's measurement produced a horrible
VSWR.....I saw Marty later on at a convention,
and I believe he said the same thing happened to him...
It took me 4 iterations to get the antenna flat
with no matching device...I of course did it at
435. But those dimensions translated very
successfully to 2M satellite, 2M repeaters, and
believe it or not to 2.4 gigs....In front of a dish, of course!!!
I had seen other pictures of the antenna, and was
very interested prior to Marty's excellent
depiction of the construction details...
I used a combination of 435 and 2M versions fixed
at about 45°, and rotated in AZ only and worked
very well with strong signal birds...
Quadfilxxxxxxxxx has the dimensions for the 3,
but the 2.4 gig computation is left as an exercise for those interested.
Nice to hear from you, Robin....R U active on any of the birds??
73, Dave wb6llo at amsat.org
Disagree: I learn....
Pulling for P3E...
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