open - short -- 0 - 180 ??
On Mon, 19 Mar 2007 16:08:17 -0700, dansawyeror wrote:
Cecil,
Thanks for the pointer. I split the sweep signal input and fed the
analyzer with 'in phase' signals. I then set the analyzer phase to a
known reading, line on the phase display. I then tested this by
comparing it to short and open. It was almost identical to the short
reading, less then about 4% difference.
This is being used to analyze a loaded dipole without any input network.
With above setup the antenna is now reading 'inductive' which is
consistent for this network.
The next step is to determine the amount of capacitance to bring the
reflection to 0j at the frequency of interest. This could result in a
reading of 0 or +/-180 degrees phase. If it is 0 then the impedance is
less then 50 Ohms, if it is 180 then the impedance is greater the 50 Ohms.
Thanks - Dan
Dan, a short represents zero impedance, thus if resistance is less than Zo with zero reactance, the phase of
the reflection coefficient is 180°. Conversely, an open represents an infinite impedance, thus if the
resistance is greater than Zo, the reflection coefficient is 0°.
Walt, W2DU
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