We call it a "ground plane" antenna.
W3HBM
On 9/10/2018 2:48 PM, Walter Underwood wrote:
From the official WWV site, the bottom element is a sloping skirt that also
serves as guy wires. Sort of like a discone with the disc replaced by a
vertical element, I guess.
"The top half of each antenna is a quarter-wavelength radiating element. The bottom
half of each antenna consists of nine quarter-wavelength wires that connect to the center
of the tower and slope downwards to the ground at a 45 degree angle. This sloping skirt
functions as the lower half of the radiating system and also guys the antenna."
https://www.nist.gov/pml/time-and-frequency-division/radio-stations/wwv
wunder
K6WRU
Walter Underwood
CM87wj
http://observer.wunderwood.org/ (my blog)
On Sep 10, 2018, at 11:41 AM, Jim Brown <[email protected]> wrote:
On 9/9/2018 7:02 PM, Wes Stewart wrote:
The WWV antennas are center-fed vertical dipoles.
Thanks for the reminder about this -- I vaguely remember reading about their
antennas years ago. Question -- from the description, is the feedpoint higher
than a quarter wave above ground? A few years ago, I did an NEC modeling study
of HF verticals that showed that doing that improved the vertical pattern and
seemed to suggest that it reduced ground losses. Your thoughts?
The study is here. http://k9yc.com/VerticalHeight.pdf
73, Jim K9YC
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