From the WWV site:
The WWV antennas are half-wave vertical antennas that radiate omnidirectional
patterns. There are actually five antennas at the station site, one for each
frequency. Each antenna is connected to a single transmitter using a rigid
coaxial line, and the site is designed so that no two coaxial lines cross. Each
antenna is mounted on a tower that is approximately one half-wavelength tall.
The tallest tower, for 2.5 MHz, is about 60 m tall. The shortest tower, for 20
MHz, is about 7.5 m tall. 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
As a side note, several years ago when my late wife and I were still traveling
around in an RV we were near Ft. Collins. As I have done with other stations I
telephoned the site and asked whether I could get a tour. The NIST guy was
incredulous and said that no way did they give tours. I said, pity, I'm an
engineer and ham and am disappointed. He thought for moment and then said,
"Actually, we have a contractor doing some work here and the gate is unlocked.
If you were to drive in and look around you wouldn't be bothered, but please
stay in your car." So we did. The WWVB antenna was pretty impressive, but
nothing like NAA in Cutler, Maine.
Wes N7WS
On 2/12/2017 8:56 PM, Fred Jensen wrote:
KFBK in Sacramento uses [or used, my info is a few years old] a center-fed
half-wave vertical ["Franklin"] antenna, said to be the only one left. It's
... interesting. [:-) KFBK is also the originator of the first out-phasing BC
TX which became the RCA Ampliphase [or Amplifuzz if you ever had to get one to
pass PoP]. KFBK is also the radio birthplace of Rush, "Bloviator in Chief,"
although that's probably far less important than the Franklin. There was a
radial field under the Franklin, it may have rusted into oblivion by now, I'm
not sure it was all that important, it's located in the flood plain north of
Sacramento ... moderately wet, they grow rice in the area.
73,
Fred ["Skip"] K6DGW
Sparks NV DM09dn
Washoe County
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