Niko AC6DD wrote:
... the 5/8 Vertical idea came from the "All About Vertical Antennas" Book.
Getting 3dB with some wire and a balloon sounded pretty good.
____________
The approximate 3 dB improvement of the radiated field of a 5/8-wave
monopole compared to a 1/4-wave monopole refer only to the maximum fields
they radiate, NOT to the fields they radiate at __all__ elevation angles.
Those maximum fields always occur in the horizontal plane, regardless of the
vertical monopole radiator length/height, and/or the conductivity of the
earth within a 1/2-wavelength radius from the base of that monopole.
This may be confirmed by referring back to the FCC document linked earlier
in this thread (
http://s20.postimg.org/olcquv94d/Monopole_Elev_Patterns.gif ).
For 1 kW of applied power, the groundwave field radiated by a perfect
1/4-wave radiator over a perfect ground plane is about 195 mV/m. For those
conditions using a 5/8-wave radiator, the field at 1 mile is about 275 mV/m.
Other things equal, this field improvement in the horizontal plane for a
5/8-wave vertical monopole relative to a 1/4-wave vertical monopole is very
close to 3 dB.
RF
_________________
Topband Reflector
|
