On 8/31/2010 3:09 PM, Richard Fry wrote:
On Aug 30, 5:52 pm, Roy wrote:

In my example, the antenna is not matched to the transmission line. Nor,
for that matter, is the transmitter matched to the transmission line. My
point is that power transfer doesn't depend on either of these points
being matched.

Roy:

My post showing very high input SWR at the base of an unloaded, base-
driven, 10 foot vertical on 3.8 MHz described an UNMATCHED system
resulting from its connection to transmission lines of typical
impedance values. It did not include matching networks, whether
located at the base of the vertical radiator, the output connector of
the transmitter, or wherever.

Then you posted, "Using your antenna as an example, suppose that a
transmitter with output Z of 50 ohms is connected to a tuner that
transforms its output impedance to 0.6 + j1250 ohms. ... The
transmitter will see 50 + j0 ohms, the antenna will see an impedance
of 0.6 + j1250 ohms, and full power will be transferred."

That configuration you posted is a MATCHED system, and its performance
does not disprove the accuracy of my post.

RF

So you're saying that the mismatch between the impedance of an antenna
and the transmission line connected to it doesn't inhibit power flow
when there's a matching network anywhere in the system. But it does
interfere with power flow when there's no matching network?

What if the antenna is 50 ohms and the transmission line is a half
wavelength of 600 ohms, for a 12:1 mismatch? There's no matching
network. The transmitter sees 50 ohms. The antenna sees 50 ohms. What
will interfere with the power flow?

Roy Lewallen, W7EL