On 8/30/2010 3:12 AM, Richard Fry wrote:
On Aug 29, 6:34 pm, Cecil wrote:

The *feedpoint impedance* of a standing-wave antenna depends upon
the *electrical* length of the antenna. If it is resistive, the reflected
wave has undergone at least a 180 degree phase shift referenced to
the forward wave. Otherwise, the feedpoint impedance would not
be purely resistive. etc

However an assumption might be taken from some posts here that a short
vertical radiator loaded to resonance is the full electrical
equivalent of an unloaded, resonant vertical of about 1/4-wavelength,
while it is not. That is my point.

RF

In the above "equivalent" is used in an interesting way. If equivalent
is used as a term of efficiency, you are absolutely correct. If you are
saying my transmitter still knows the difference between a "straight"
1/4 wave and an "equivalent loaded" antenna, the use becomes false ...
i.e., when I dip the loaded antenna with my GDO, and the antenna is
properly constructed, it tells me I have the "true" equivalent of a 1/4
wave.

Regards,
JS