sci.physics.electromag

On Sep 12, 1:22 pm, "Bill Miller"
wrote:
[...]
> In "real" antennas (disregarding "long" antennas that are multiples of a
> wavelength) radiation is broadside to the conductor and near zero off the
> ends. I'm not familiar with the calculation you refer to.

There are many kinds of real antennas that radiate towards the ends.
These are called end-fire antennas, the most familiar probably to most
people is the Yagi-Uda. There is nothing that prevents a metallic
structure to radiate into any particular direction if the current
distribution over it is properly designed.


[...]

> Generally, balls on the end of an antenna seem most useful in reducing or
> eliminating corona discharge -- an important issue at higher power levels.
> They seem to have little or nothing to do with the function of radiating
> signals.
>

Balls or other metallic stuff on the ends can act as lumped element,
usually inductive, loading that reduce the size of the antenna while
maintaining its resonant frequency.