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Re: Helix Match: Network Analysis



Fred,

> So, sorry to Mike AF9Y and the group if my comments were misconstrued
>  on this... In my opinion anyone building their own ham equipment should 
have 
>  resepect and encouragement.  AF9Y has done more than
>  most of us, including me, to advance ham radio technology, and
>  I feel bad that I (totally unintentionally) probably upset him.  And
>  this goes for K5OE as well (in case I upset YOU!)... keep up the good 
>  work...

I was not upset at all, only mystified by your results.  I do not have access 
to any sophisticated test equipment, hence my original desire to "play 
around" at 70 cm first.  I was able to duplicate the AF9Y design with 
excellent results at 70 cm, as I reported (excellent results being an easy 
low-impedance match).  That 3-ring double-helix with ring reflector on 70 cm 
was a terrific antenna for mode B uplink.  It handily outperformed my TPM II 
for both AO-10 and SO-35.  Unfortunately, it appeared way too broadbanded for 
my tastes as a downlink antenna.

I then casually scaled that design to a 10-turn 2.4 GHz, but had no means of 
testing other than relative signal strength.  When I achieved the best signal 
I could determine on my "test bench,"  I put the antenna on the air and was 
immediately (literally 20 minutes later) able to copy the beacon on UO-11.  
Due to work and family, I have not been able to get back to that project to 
experiment more with the ring(s).  

I have built some models in  NEC4Win95 (virtual version) and found the 
position of the ring reflector to not be very critical, but the circumference 
is very touchy with regard to feedpoint impedance.  I keep trying to find an 
hour or two and attempt to model the multiple-ring version proposed by W8JK 
more than a decade ago.  Dave, ZL2AMD, is also doing some modeling on tapered 
versions and has some exciting results for improved pattern.  He may wish to 
comment as well.
73,
Jerry, K5OE
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