In article ,
Jeff Liebermann wrote:

I forgot to connect my comments to the original question. Sorry(tm).
You're correct. There's no way to get a good isotropic radiator
pattern with a simple vertical radiator. However, you can still get
fairly close if you make the antenna sufficiently small relative to
the operating wavelength. As the physical antenna size approaches a
point radiator, the pattern starts to look rather spherical.

The difference in pattern between a half-wavelength dipole,
and an infinitesimally-short dipole (i.e. one whose length
approaches a point source) is actually quite small. Both are
torus-shaped patterns, with a deep null along the axis of the antenna
(theoretically, the null is infinitely deep directly along the axis).

An infinitesimally-short dipole has a maximum gain of 1.76 dBi.

A half-wavelength dipole has a gain of 2.15 dBi.

There really isn't much to distinguish the two, as far as the pattern
and gain go.

Unfortunately, the gain drops, efficiency drops, and feed point
impedance drops, resulting in a rather inferior antenna.

Yeah, the low radiation resistance and high reactance of the short
dipole are its biggest drawbacks.

--
Dave Platt AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
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