Re: [amsat-bb] 2.4 Ghz Helix--stacking distance

[K5OE@xxxxxxx]

Jess, Pieter,

> I've run the numbers I found in the the UHF/Microwave Experimemter's
>  Manual and they seem to incicate that the optimum stacking distance for
>  two 20 turn helicies is about a foot.  Can someone tell me if that is
>  close to the correct value?  It seems a little close to me considering
>  the boom length is about 2 feet.

Exactly what do they say?  That would be 2.5 wavelengths, double the 
"typical" stacking distance for a Yagi--typically 1.25 lambda.  If capture 
area and beamwidth are the contributing elements, then a 16 dB antenna of any 
type has a "similar" pattern (of course the sidelobes are worse in a helix).  
The ARRL Handbook and a QST article from 1963 both specify 1.5 WL for 
stacking 2x2--or about 7.5".  The famous AF9Y 2x2 array has spacing that 
scales to 10.5" at 2401 MHz.  My limited Xerox copies of Kraus' work do not 
address this issue.  I hope somebody that has more authoritative references 
chimes in and offers some input, as I already have one based on 1.5 WL in the 
works (garage).  
  
>  Yea, I know, I should buy a dish but I'm hardheaded!
DItto!  And I have both a 2' and a 3' dish... but I want this to work :-)  
73,
Jerry, K5OE
----
Via the amsat-bb mailing list at AMSAT.ORG courtesy of AMSAT-NA.
To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org