On 27 Nov, 06:18, Cecil Moore wrote:
John Smith wrote:
1/2 wave monopoles
have little dependence of a full counterpoise or ground for, at least,
acceptable performance.

The Zepp antenna is a 1/2WL monopole with no
counterpoise.
--
73, Cecil http://www.w5dxp.com

That makes sense. Physically it is half wave
but electrically it is a full wave antenna.
It is able to radiate on its surface and is unable to radiate
as it returns down the center of the wire.
(assuming the antenna is not tubular)
The path on the outside is helical which promotes a slow wave
so the physical wavelength has to be increased slightly to
compensate.When JS made his Vincent model the physical
length was slightly longer than a electrical half wave length
because of this so it still was not quite balanced.
To bring the antenna into balance there must be a contrawound
widing put into place such that the radiating current on the
return path is exposed and not enclosed. Doing this will not
correct the slow wave phenomina but will neutralise the
increased inductance created by the windings and at the same time
bring the radiator back to equilibrium where the correct LC ratio
is maintained and the radiator is a full electrical wavelength in
equilibrium and of variable shape and elevation.
Sound familiar?
Art Unwin.....KB9MZ...xg
Note the wire center contains no inductive or capacitive
properties, only resistive. Thus radiation will be slightly
over 50% of a full wave radiator.