The current that flows into the antenna structure (two bars) radiate.
So part of the incident field is reradiated by the dipole. It doesn't
matter whether the antenna current is caused by a transmitter or
incident field.

Win,

your explanation is very good and convincing. I believe that most of us would
read with interest some further remarks on what happens in the case of a shorted
element (e.g. a director or a reflector), instead of the driven element.

In those cases all received energy must be re-radiated, but more details on that
mechanism would be welcome.

73

Tony I0JX

Antonio Vernucci wrote:
Win,

your explanation is very good and convincing. I believe that most of us
would read with interest some further remarks on what happens in the
case of a shorted element (e.g. a director or a reflector), instead of
the driven element.

In those cases all received energy must be re-radiated, but more details
on that mechanism would be welcome.

The impinging field induces a current on the element. The current
produces a field which radiates. An AC current flowing on a conductor
creates a field regardless of how that current is produced. It doesn't
matter whether the current is due to conduction from a source, by
induction from a field, or any combination of the two -- the field
resulting from the current is exactly the same. Yagis and other
"parasitic" arrays depend entirely on this phenomenon for their operation.

Roy Lewallen, W7EL