Might I suggest that we continue to meet via Zoom on Monday evenings at 7 pm (EST) to share what we know about the VNA?
I don¡¯t see my talk as a ¡°lecture¡± to record and watch. I¡¯m not a VNA engineer.
But I can see why this technique (record and play back) might work for some who just can¡¯t make the ¡°live¡± session.
We have met three times now via Zoom and discussed these topics:
1) What is a VNA and in broad strokes how does it work?
I compared the VNA to a dolphin or a bat and SONAR - what do you learn from the reflected SOUND waves
2) Why is CALIBRATING the device over a frequency range important - and how do you do that?
The SAVER software makes this process easy - and I can save a file with thousands of data points.
We then talked about
Why an antenna has a resistance, a reactance, and an impedance?
What kinds of graphs can you plot to understand an antenna?
I did a live demo with my own 80m dipole in my yard.
3) Yesterday we talked about some of the VNA guts
Reflection Coefficient (rho) as a RATIO of reflected voltage to forward voltage and why 0<rho<1
RETURN LOSS - what is it, why is it measured in decibels, and why is it a positive value
SWR - how is this related to reflection coefficient and Return Loss
We ran out of time (8 pm EST) and stopped but there were some good questions and discussions.
Might I suggest we continue to meet via Zoom on Monday evenings at 7 pm EST.
I realize that makes it awful for other time zones distant from N.America
I hinted that I could use my own Nano VNA (model 4 H) to help me adjust my MANUAL antenna tuner for HF antennas.
I then showed how the various graphs (SWR, Return Loss) change as I mess with the capacitor/inductor setting in my ¡°TUNER¡±.
So come join in on this discussion of Nano VNA next Monday evening.
De k3eui Barry
Philadelphia PA USA
Barry K3EUI