"art" wrote in message
ups.com...
If you compare any fractional ground mounted antenna with a
full wave antenna the radius of the field will have a difference
of aprox 3 db and the resistive impedance will have a ratio of two
to one. Note that gain is a measure of one radiator level against
another and is no way a distorted field of radiation that has been
manipulated by an additional near by radiator.
__________

art -- the difference in the gains of ground-mounted monopole radiators of
different heights is related to the height of the monopole, and the effect
that has on its r-f current distribution; therefore its radiation pattern.

The link below leads to a pattern and gain comparison of several monopole
heights commonly used in commercial AM broadcasting, over a perfect ground
plane.

Note that a 1/2-wave, ground-mounted monopole for these conditions has a
pattern and gain identical to that of a 1-wave, center-fed dipole in free
space. Also note that there are three radiator heights taller than
1/2-wave, whose gains are higher than the 1/2-wave (or a full wave in free
space).

In all cases, the area under the curve is the same for each radiator plotted
(mind the dB scale), showing that for a given input power each monopole
radiates the same total power into space regardless of the shape of its
pattern.

No nearby radiator was needed or used in the generation of these patterns.

So there's something for you to consider while you're gone for a month.

http://i62.photobucket.com/albums/h8...Comparison.jpg

RF