"The first permanent use of an elevated radial ground system appears to be
at WPCI, 1490 kHz in Greenville, South Carolina. This installation,
designed by William A. Culpepper, involved replacing a standard buried
system with a four wire elevated system consisting of #10 solid copper
wire, one quarter wave in length, and supported on treated wooden posts
which keep the radials 4.9 meters above ground. The antenna radiation
efficiency, based on field strength readings on the eight cardinal
radials, was 302 mV/m at 1 kilometer versus the predicted FCC value of 307
mV/m. The WPCI installation was unique in that the tower was base
insulated but the radials came right up to the tower, 4.9 meters above
ground and terminated in insulators. The tower was fed from the tuning
unit, through a piece of coax to the 5 meter point on the tower where the
center conductor of the coax was attached to the tower and the shield to
the elevated radials. This feed system resulted in a higher feed
resistance than would normally be expected. Data on this facility was
taken from the FCC files."
An intriguing paper. Nice to see something actually based on science and
true field measurements. A couple of questions. With the radials being 4.9
meters above ground, do the radials literally come up to the tower and then
travel down the leg to connect to the ground side of the insulator or do
they travel in close to the tower and angle downward? Does a FS measurement
taken at 1 kilometer fully reflect the true angle of radiation and overall
performance of the antenna for purposes of distant signals?
73. . . Dave
W0FLS
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