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Re: R: qha article in the may/june journal



Domenico, and Wally; glad you both brought this item up.  I was a bit confused
also.  This article clarifies right and left hand circular polarization nicely.
The only sure way was to compare with a short helix which is fine on lower bands
but rather difficult on 2400 MHz!   Cliff K7RR

i8cvs wrote:
> 
> ----- Original Message -----
> From: Wallace Strom <kg4yuw@arrl.net>
> To: <amsat-bb@AMSAT.Org>
> Sent: Wednesday, June 09, 2004 11:57 PM
> Subject: [amsat-bb] qha article in the may/june journal
> 
> > I have a question about the qha article - it seem that the big bifilar
> > is inside the small bifilar.  How can this be when the length of the big
> > bifilar is .260 of a wave length and the small bifilar is .238 of a wave
> > length?  In the satellite handbook, fig 10-17 when combined with table
> > 10.6 depicts the same set up.
> >
> > 73,
> >
> > Wally
> > kg4yuw
> >
> Hi Wally,KG4YUW
> 
> I tryed to answere to your previous messages but your email address was
> refused.
> 
> About the lenght of the large bifilar wich is inside to the small bifilar
> table 10.6 of the satellite handbook call for D wich is the diameter of
> imaginary cylinder on wich bifilar is wound and L is the axial lenght of
> the bifilar.
> 
> For the large bifilar the diameter D is greater or 0.173 of a wavelenght so
> that you must adjust the shape in such a way the large bifilar do not touch
> the small bifilar.
> 
> The data reported in the "Satellite Experimenter's Handbook" by K2UBC
> are the same of those reported by Walter Maxwell W2DU in his book
> "Reflections Transmission Lines and Antennas" and they are the same in
> my article on may/june of AMSAT Journal.
> 
> I aegree with you that L = 0.260 for the large bifilar cannot fit inside of
> L=0.238 for the small bifilar and this has been an head aches for me as
> well but at the end i got some peace-of-mind reading the note on the
> satellite handbook "Dimensions should be regarded only as a guide".
> 
> If you look at Photo-1 page 6 of my article in the AMSAT Journal you
> will realize that the axial lenght L on each of the four sample is slightly
> different from one to the other because during SWR and pattern measurements
> in my lab D and L where individually adjusted compressing and enlarging
> the bifilars to match them for the best compromise by hand and instruments
> because all considering each prototype has a different story.
> 
> Best 73" de
> 
> i8CVS Domenico
> 
> > ----
> > Sent via amsat-bb@amsat.org. Opinions expressed are those of the author.
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> >
> 
> ----
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----
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