Last week I installed a 3 element 17 an a 4 element 12 interlaced on a 14ft
boom 7 ft above my Bencher SkyHawk tri band antenna.
The feed point impedance and band width of the 12/17 antennas were as
expected. A quick plot of the SkyHawk was another issue.
14 MHZ had no change in feed point impedances and band width, the 21 MHZ still
exhibited the charteristics of the original SkyHawk.
But 28 MHZ was another story, From it’s original flat arcing SWR curve
28.000 to 29.100 I now have a SHARP rising 2.3:1 standing wave ratio @ 28.475
that descends to 1:3 :1 at
28.655 MHZ the band width and top end impedance cure resembles the prier
measurement B-4 the new installation.
The antenna in question has only one driven element insulated ( the director
and reflector at ground potential) and it used cell illumination for the 12
meter segments. ( all 4 elements are at ground potential ) on a 14 ft boom .
Wayne W3EA
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