On Thu, 18 Dec 2003 07:29:39 +0000, William F. Hagen wrote:

an antenna has an impedence at the frequency it is being used at, and an
impedence at its resonant frequency. If either of these impedences
happen to be 50 ohms and the coax being used is 50 ohms, and the
transciever is working at 50 ohms, then the swr is 1:1, and the swr is
on the transmission line, not on the antenna.

The antenna does not have to have an impedence of 50 ohms at either the
frequency being used at or at its resonant frequency, and these two
freqeuncies could be the same, and the transmission line does not have
to be at 50 ohms, and for that matter neither does the transciever. If
any one of these is mismatched, then the swr is not 1:1.
An impedence transformer at the antenna-transmission line junction will
transform a mismatch so there is no reflection on the transmission line,
amd if this impedence is the same as that of the transmitter, then the
swr is 1:1, if the impedence is not the same, then the swr is not 1:1
unless it is also transformed at the transmitter, and again the swr
would be 1:1 on the transmission line, which is where the swr is, it
is not on the antenna.


I was going to say something similar. a 1:1 SWR means that the Load
matches the Transmission line. It says nothing about the condition of the
antenna. Most antennas have a matching system or "Tunner" built into
them, like a Gama Match for example, to transform their Impedance back to
the standard 50ohm coaxial transmission line.

Ron