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RE: HELIX ANTENNA reply to bill's comments



Bill,
Thanks for you e-mail.
I love the Helix. I have used it for almost 40 years (since I was a kid,Hi
Hi). Used on NOAA LEO Weather birds and Oscar 6-7. I now use a 15 turn  on
my AO40 L band uplink. Works great. Am driving it with 80 watts TPO.

I always let the helix mark the point on the backplane. Where it intersects
the reflector is the point. There is the issue of match. The helix is in the
area of 106 ohms , so I use the tried and true procedure of adding a 1/4 to
1/2 inch flat piece of copper affixed to the helix conductor starting right
after the N connector and running basically parallel with the reflector. I
trim to best SWR. It is simple, very forgiving, and work great.
Many people, my self included, also use them as feeds for dishes. I prefer a
patch feed but that is not always possible. I think a good example is in my
Florida Portable which is a 60cm dish with two helix feeds concentrically
wound as uplink and downlink. See: www.wmfd.com/w8gsm "Portable"
Give one a try. I think you enjoy the ease of construction and use.
73
Gunther Meisse
W8GSM


-----Original Message-----
From: walnuthil@juno.com [mailto:walnuthil@juno.com]
Sent: Friday, September 27, 2002 3:45 PM
To: W8GSM@amsat.org
Subject: HELIX ANTENNA


Hello Gunther,
Saw your posting on Helix Antenna Calculator, I was considering
building a helix, but most of the reports I've seen are mixed results.

I was wondering if you had built any of these antennas, and what
sort of results have you gotten?

Also, do you have any idea as to the location of the feed point on
the backplane. This point seems to vary from report to report.

73 Bill
WA1DMV@amsat.org


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