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Quadifillar Helix tests



Hi All,
Experiments here have focused on a 1 wavelength, 1 turn QFH for receive on
70 cm. I have had good results down to 5 degrees elevation on some passes of
AO-51 and FO-29. The signal strength on my 820 H bar graph typically is S5
with an S9 with AO-51 on high power.
FO-29 reception varies, sometimes the pass has good reception and other
times very poor, the South side always worse than North side. Currently the
antenna is on my patio roof on a 3' mast, and I may have some tree
absorbency to the South and West. Mountains limit my Eastern view to about
12 Degrees elevation.
Caculated performance of this antenna is about 3 dBic at 30 degrees, -1 dBic
at zenith and  the horizon. As this antenna is circular it does not loose 3
dB as linear antennas do, plus the gain at 30 degrees helps even out the
signal during the pass. Even with the loss in gain at the zenith signals are
still stronger than at 30 Degrees elevation.
For current construction, I am using bare # 14 Ga. house wire for the
elements, with the bottom end soldered to the mast. Dia is now 4.375 " and
an axial length of about 19"  Total element lengths are 25.3 and 27.3
Inches. The elements viewed from the top are wound  counter clockwise, and I
am using a Bazooka Balun, formed by the mast and 6.7" of  141 hardline
inside the mast before grounding the outside of the line to the inside of
the mast. A short piece of 3 " ABS  sewer pipe was used to form the element
shape.

The next step is to weather proof the antenna and get it in the clear for
further evaluation of performance.

Art ,
KC6UQH
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