i Have asked this before but my post seems to have been lost.

From experience and being taught i now what to expect as a result for a return loss measurement .
From experience and being taught i know what to expect as a result for a vswr measurement.
These are common knowledge results but has anyone put together a list of expected results that are good for any of the other measurements we can do .As a noob to vna's i am finding i get results but what are good and what are bad.

some explanation of what you see on the screen and what you expect to see would be good but every video i have watched does not go into that detail they expect you to know that answer. well I've got to be taught it first to know it. anyone willing to teach an old dog new tricks?

or at least point me to some where i can read with out loads of maths that i do not understand. I need a bit of spoon feeding of what i see on the screen in relation to the maths or vice verse.

Where are you located?

Alan

Have you looked at the Wikipedia article on the Smith chart?:

https://en.wikipedia.org/wiki/Smith_chart

It has a lot of math, but it also gives a description of how a given impedance (resistance + capacitive or inductive reactance) gives different measured values with different lengths of transmission line (coax, etc.) between the measuring device and the device being measured. Some values change with line length, some (like VSWR or return loss) don't change (much). If you are generally familiar with AC circuits involving inductance and capacitance, the Smith Chart can help understand how impedance varies along a transmission line, and the VNA is a tool that actually does those measurements over a range of frequencies.

For understanding impedance in general, you could look at old versions of the ARRL Handbook which can be found online.

--John Gord

On Fri, May 15, 2020 at 01:36 PM, <m1dgq1@...> wrote:

... some explanation of what you see on the screen and what you expect to see would be good ...
============================================
From a terminal program if you enter "data 0" ( CH0 s11 values), or "data 1" (CH1 s21 values) you will receive 101 complex data pairs in real/imaginary format from the NanoVNA for CH0 or CH1, respectively. The 101 real/imaginary data points represent the 101 display points on the NanoVNA. All measurements displayed by the NanoVNA, or shown by any NanoVNA software program are derived from the complex data pairs values.

For example:
If s = the complex s21 data values returned by "data 1" (i.e. 0.365322053 -0.903783857)
then:
20*log10(abs(s)) is equal to the CH1 LOGMAG value displayed on the NanoVNA
similarly:
if a = angle(s) CH1 angle in radians
then:
rad2deg(a) is equal to the CH1 PHASE value displayed on the NanoVNA

All other displayed values are likewise derived from the base complex data pair and their formulas can be found on the internet, or by looking at how an open source program like NanoVNA-Saver calculates them.

- Herb