Szczepan Białek wrote:
Now you have to decide what your half wave antenna is going to do.
Charge up only and let the power leak away or radiate without having
any power!
A 1/2WL dipole is a standing-wave antenna. Believe it
or not, ~80% of the steady-state energy on a 1/2WL dipole
is not radiated, i.e. as far as total energy is concerned,
radiation is a secondary effect. Energy is traveling in both
directions at the same time on a standing-wave antenna. At
the tip of the antenna, the two energy flows are equal. At
the feedpoint, the reflected wave is only ~20% down in
energy level from the forward wave - the reflected voltage
and current are only ~10% down from the forward voltage and
current. The feedpoint impedance of a 1/2WL dipole is the
result of superposition of the forward and reflected waves.
The Z0 of a 1/2WL dipole using #14 wire at a height of 30
feet is very close to 600 ohms.
--
73, Cecil, IEEE, OOTC,
http://www.w5dxp.com