Question:
Installed a ½ wave 40 meter dipole 10ft above the penthouse roof which
is 410ft above sea level and 210ft above average terrain. The dipole is
almost perfectly horizontal.
We get a dip on the antenna analyzer around 7Mhz but the SWR is 7.5:1 at
the dip and just goes up from there. I presume there is something going
on with the roof which is concrete covered with 4? Styrofoam and a layer
of creek stones.
Thinking about installing a lumped inductance across the feed-point and
using the center conductor of the 50 ohm coax to tap the coil where we
find a 1.1:1 SWR.
Looking for other ideas and suggestions as to how best to match the
input impedance.
73,
dave
wa3gin
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