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R: qha article in the may/june journal




----- 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 

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