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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List Sponsor: Are you thinking about installing a tower this summer? Call us
for information on our fabulous Trylon Titan self-supporting towers - up to
96-feet for less than $2000! at 888-833-3104 <A
HREF="http://www.ChampionRadio.com";>
www.ChampionRadio.com</A>
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