"Richard Fry" wrote
...
On Sep 13, 12:57 pm, Szczepan Bia³ek wrote:
If the current oscilate at the
ends is developed the very high voltage. The high voltage produce the
electric field. So you can wrote: "the electric field is a direct
consequence of voltage developed in the ends of the transmitting antenna".
This electric field generate the magnetic field and so on. So the Hertz'
dipole has the three sources of waves. The centre and the two ends.

Only the change in current and charge, over time, produces EM
radiation. That radiation includes both the magnetic and electric
fields, at right angles to each other and to the direction of travel.

In the case of a self-resonant, center-fed, 1/4-wave dipole, current
is maximum at the feedpoint and minimum at the ends of the dipole.
Therefore the ends radiate very little of the total applied power.

Below is what John Kraus writes about this in Antennas, 3rd edition,
page 12:

QUOTE
A radio antenna may be defined as the structure associated with the
region of transition between a guided wave and a free-space wave, or
vice-versa. Antennas convert electrons to photons, or vice-versa.

Regardless of antenna type, all involve the same basic principle that
radiation is produced by accelerated (or decelerated) charge. The
basic equation of radiation may be expressed simply as:

IL = Qv (A m s^-1)

where

I = time-changing current, A s^-1
L = length of current element, m
Q = charge, C
v = time change of velocity which equals the acceleration of the
charge, m s^-2

Thus, time-changing current radiates and accelerated charge radiates.

In which parts of antenna the charges acclerate?
S*