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2.4 Ghz Helix Match



Good Morning,

Last year while I was building my quad helix for AO-40 I built about a
dozen helix antennas of one form or another.  I tried all the known
methods of matching using one of the 2.4 Ghz bridges described in the
AMSAT-NA Journal a couple of years ago.  I couldn't tell much difference
in any of the methods.  I finally settled on a straight piece of brass
1.25 inches by .25 inches.  I used 1 inch PVC for a boom and mounted the
input connector as close to the boom as possible.  I soldered the
matching strip to the connector and angled it in toward the boom to
intersect the beginning of he helix element.  I soldered the copper
elements to the end of the strip and even fastened aluminum elements to
it with a flat headed screw and an "eye" in the end of the aluminum
element.  Spacing the matching strip about one sixteenth inch from the
reflector resulted in a perfect match every time.  Adjusting the spacing
was accomplished by sliding the turns of the helix in and out until a
match was found.  RTV was used to fix the windings to the boom at that
point  Shaping the matching strip around the boom did not improve the
match or performance.

73's de Jess - W4MVB

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