[TowerTalk] K8UR wire 4-SQR characteristics vs 1/4 vertical array design from N0AH

[Jim Reid]

Steve wrote,  in part:

> There is a section in ON4UN's book about the need for an extensive
> ground system with half-wave verticals, contrary to "popular myth".
> 
> I assume he is talking of base-fed half waves, but wonder why center
> fed half waves would be immune from this requirement?

They are not.

They need them;  why?  Because the lower end of the half
wave vertical is near the ground -- unless it is somehow
elevated way high.

The end of the vertical dipole is a very high E field/high Z  
area.  So electrical field lines go from there,  where?  A lot
to the ground,  and as the potential of the field rises
and falls,  more or less charge flow is induced into
the ground surface where the field lines terminate --
so you would wish that surface to be as highly
conductive as possible; why, to  minimize power loss to the
resistively of the ground surface/skin depth penetration
area.

Sure,  some of those lower end E field lines will return
to the upper half of the dipole,  where we wish they
all would go;  but they all don't.  Those that don't
cause ground current to "warm the sand fleas",
if you are on the beach.

Here on Kauai where WWVH uses all 1/2 wave vertical
dipole arrays to beam their signals to the Western
Pacific,  there are large and extensive radial systems
below each 1/2 wave tower.  And those verticals are
each adjacent to the ocean beach.

73,  Jim,  KH7M




--
FAQ on WWW:               http://www.contesting.com/FAQ/towertalk
Submissions:              towertalk@contesting.com
Administrative requests:  towertalk-REQUEST@contesting.com
Problems:                 owner-towertalk@contesting.com