Albert,
My take... When one talks of distributed circuits like a coax cable or
waveguides, the space (and time) origin to solve the Maxwell equations must
be set: in the case of guided propagation like in the coax/waveguide
examples, the propagation occurs in one direction (along the cable) and the
fields are essentially solved on the (x,y) plane where they stay the same
because they do not propagate.
Since the measurement the NanoVNA offers is ideally under steady state
conditions (where the solution to the Maxwell equations is not too
complicated), the reference plane can be thought of as the point in space
along the direction of propagation where the phase of the incident signal
is set to 0.
Hope it makes sense, it's a nice question!
Thanks,
Luciano
On Sat, Sep 25, 2021, 11:23 AM kk7xo via groups.io <kk7xo=
[email protected]> wrote:
As far as I can tell, calibration is done at a single point in a circuit.
A plane suggests two dimensions, and that anywhere on that two dimensional
object, the calibration is the same. But everyone knows that even for a
solid copper plane, only one point can be considered 0 volts, and every
other point on that plane has resistance, inductance, and capacitance
relative to that one point.
So, why do people talk about the "plane" of calibration, rather than the
point of calibration?
73 de Albert KK7XO
