Isn't it necessary to define an impedance against which the antenna input
impedance and SWR is referenced? It may not always be 50 ohms or some other
"standard" impedance.

For example, a self-resonant 1/2-wave dipole in free space has an input Z of
about 65 +j0 ohms, but will not constitute a 1:1 SWR to an r-f system that
otherwise is 50 ohms, even though antenna reactance is zero.

RF
_________


"Roy Lewallen" wrote:
The point of minimum Z (that is, minimum magnitude of Z) will probably be
close to resonance. Resonance is the frequency at which the reactance is
zero. In a typical antenna near resonance, the reactance changes much
faster than resistance with frequency. This causes the magnitude of the
impedance, and the SWR, to be minimum near the resonant frequency. It
should be true for the antennas you asked about. It isn't true for all
antennas, however.

Roy Lewallen, W7EL

dansawyeror wrote:
Is minimum Z, across a frequency scan, 'resonance' on a 1/4 wave
vertical?

Is it resonance on a center loaded vertical?

Thanks - Dan kb0qil