[Antennas] vertical dipoles

[Alan C. Zack]

The WWVH setup reminds me of my travels to the Coast Guard LORAN C stations
on Kure, Wake, Marcus, Iwo Jima, Yap, Palau, Kwaj, Con Son, Sattihep, plus
a few more.  I believe those were 600 ft towers if I remember correctly. 
French Frigate, Ulithi, and the other LORAN A stations had shorter towers. 
But these were not half wave, but quarter wave antennas.  Looks like
exactly the same design for the buildings, etc. 
73

Jim Reid wrote:
> 
> Terry wrote,  in part:
> 
> > I 'd like some info on vertical dipoles, and don't seem to be able to
> > find a good source.
> >
> > Do they need a good ground system (I'd guess not, ....
> 
> Yes,  they do need a good radial system;  otherwise
> you will lost up to 6 dB of signal (-75% of rig output power!).
> 
> Best example is right here on Kauai where I live.  Have
> a look at the WWVH site info:
> 
> "The 5, 10, and 15 MHz antennas are phased array vertical
> dipoles. They consist of two half-wave vertical dipoles that
> are separated by a quarter-wavelength and driven 90 degrees
> out of phase. These antennas radiate a cardioid pattern with
> the maximum gain pointed toward the west."
> 
> And here is a link to a photo of the 15 MHz array of half wave,
> vertical dipoles at WWVH:
> 
> http://www.boulder.nist.gov/timefreq/images/radiostations/wwvh-large/wwvh5.j
> pg
> 
> Now,  note the many radials,  on the ground,  going under the
> fence in the foreground of the photo.  Note the center insulator
> of the Rohn towers of the verticals.  These actually might be
> called sleeve verticals,  since the coax runs up the center of
> the tower,  but is shielded from the lower half of the dipole
> by the many sloping "elevated radials" down from the feedpoint
> to the ground (these are the lower half of the dipole).
> 
> The radials were found to be absolutely needed to regain the field
> strength out in the far Western Pacific to which the WWVH siganl
> is directed by these vertical dipole phased arrays.
> 
> Have fun.
> 
> 73,  Jim KH7M
> On the Garden Island of Kauai
> 
> - - -
> 
> Your moderator for this list is:
> Larry Wilson KE1HZ antennas-owner@mailman.qth.net
> _______________________________________________
> Antennas mailing list
> Antennas@mailman.qth.net
> http://mailman.qth.net/mailman/listinfo/antennas

-- 
__________________________________________________________________________                       

		      Amateur Radio Station K6ACZ
                     Anaheim, Southern California, USA
                Quality Engineer, The Boeing Company, Retired
         Aviation Chief Warrant Officer, U.S. Coast Guard, Retired
                U.S. Coast Guard, Always Ready, Always There
        Every hour, Every day, Around the Clock and Around the World
                              SEMPER PARATUS