1) Be sure your coax is less than 1/4-wavelength long in the coax
(considering Vp). Conversely, be sure your measurement frequency of
measurement is less than the electrical length of the cable.
2) Open terminate the far end of the cable.
3) On the Smith chart more-or-less in the center of the locus, note the
capacitance.
4) Short terminate the far end of the cable.
Do not change frequency or move your measurement frequency.
5) On the Smith Chart note the inductance.
6) Calculate the impedance using:
Zo = SQRT [ L / C ]
Dave - W?LEV
On Tue, Nov 7, 2023 at 8:58?PM Russell C. Nixon <rcnixon@...>
wrote:
Can someone point me to a reference in the Wiki for screen scaling? I¡¯m
trying w1aew¡¯s method for determining the characteristic impedance of an
unknown piece of coax as an exercise. I¡¯m getting close but the Smith chart
trace is a tight little knot in the center. W1aew¡¯s video shows a nice
¡°ram¡¯s horn¡± trace on the Smith chart. I think the scaling will be useful
in other areas too. Thanks in advance.
--
*Dave - W?LEV*
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Dave - W?LEV
