A DC source has no complex portion and is not characterized by impedance,
only the real term in the R ¡À jX. Further, if no current is drawn from the
source, the presence of the R term isn''t there. The ¡À jX term requires AC
and is absent for DC. However, once you draw a varying current from that
DC source as in SSB or keyed RF (CW), then the complex portion appears.
Example: Take AWG #000 (or whatever) large solid copper conductor. At DC,
the cross sectional current density is homogenous. However, even at 60 Hz,
skin effect due to resistance and inductance (+ jX) is evident and
measurable. The cross sectional current density is no longer homogenous
even at 60 Hz.
Dave - W?LEV
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On Tue, Jul 6, 2021 at 9:53 PM Jim Lux <jim@...> wrote:
On 7/6/21 8:46 PM, Anne Ranch wrote:
My favorite question , not directly related to nanoVNA
Why is having minimal SWR important ?
Optional answer:
SWR is an indicator of IMPEDANCE match between x and y devices -
directly related to "power transfer" between. source - TX - and load -
antenna.
Demonstrate by applying Ohm's law.
Which breaks horribly if your source has very high or very low impedance
- Consider a DC power supply.
--
*Dave - W?LEV*
*Just Let Darwin Work*
