On Tue, 11 Jan 2005 08:50:27 -0000, "Airy R.Bean"
wrote:

Such an excellent and succint didactic exposition deserves
wider recognition.....

Whilst an interesting contribution, for which thanks are due to the
OP, many of us knew this already. Didn't you, Bean? If you already
knew this, why have you not explained it before? Can't you write in
excellent, succinct, and/or didactic fashion? Or have you just gone up
the learning curve?

"Walter Maxwell" wrote in message
.. .
Assuming the terminal resistance of a resonant dipole is 72 ohms,
then a ground plane separating the halves of the dipole means the
terminal resistance of each half is 36 ohms. Thus the terminal
resistance of the half-dipole over the ground plane is also 36 ohms.
The terminal resistance of the half dipole operating against the
radials bent down can then be any value between 36 and 72 ohms,
depending on the angle of the bending. If the bending changes the
angle from 90° to 180° the resistance has changed from 36 to 72 ohms.
The terminal resistance will be 50 ohms at some angle in between, and
is usually close to 45°.
Hope this helps in understanding what occurs from bending the radials
downward.
Walt, W2DU


--
from
Aero Spike