[TowerTalk] Half Wave Verticals @ WWV/VH

[antipode]

Jim,

When I try the WWV URL below you've provided, it appears to be password
protected.  What gives?

Bill
W5IQJ




Jim Reid wrote:
> 
> Hi all,
> 
> Now,  those interested,  can view an excellent photo
> of the 1/2 wave verticals at WWV and WWVH.  Read
> the text below the photo.  There you will discover WWV/
> WWVH use elevated 1/4 wave verticals for
> these HF radiators each with 9  sloping,  elevated
> resonant radials!!!  If you look closely at the photo, you
> will see the several elevated radials;  they come down
> at a very steep angle,  and probably act more as a
> real lower vertical section than what we think of as
> elevated radials.  The discussion about the antennas is
> a paragraph or two down below the photo.  Note the
> text says the radiating radials come down at a 45 degree
> angle,  but sure does not appear to be so in the photo.
> 
> Go to: http://www.boulder.nist.gov/timefreq/stations/wwv.html
> 
> You can easily see the center insulators of the towers.
> What is not shown, nor discussed is the huge and extensive
> ground radial field at each site.  This ground "screen" field
> had to be installed to recover several dB of signal strength
> out in the far Western Pacific from WWVH.  Why? Because
> of the high E-field at the lower end of the down sloping radials.
> The E-field at the ends of these sloping radials is very intense
> because of the very high RF voltage at the radial ends driven
> by the 10kW transmitters!  These fields induced very high
> currents into the ground,  but the radial field eliminates much
> of the ohmic loss of the induced current,  thus recovering the
> former lost field strength.  Also looking closely,  you can see the
> feed coax going up to the center feed point in the inside of the
> right hand tower in the photo (this photo is of one of the phased
> array pair out here at WWVH).  Out here,  these arrays are
> right on the beach within the confines of the Navy's Barking
> Sands facilities.
> 
> If you are curious, there is much other info about these stations
> available on the site link above.  Note that NIST is now conducting
> a survey about the use of these stations to the HF using community.
> Should you want to be sure these stations continue to operate( a
> pretty high cost must be spent to replace the 30 year old antennas
> out here at WWVH) you may participate in this survey at:
> 
> http://www.timesurvey.nist.gov/
> 
> Hope you find this info interesting as I have.
> 
> 73,  Jim  KH7M
> On the Garden Island of Kauai and only about
> 18 miles from WWVH.
> 
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