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On Tue, May 31, 2022 at 11:26 AM, Roger Need wrote:

On Tue, May 31, 2022 at 06:33 AM, Jean-Marie Polard wrote:

I have a problem with the NanoVNA-H(4) and NanoVNA-App

I can connect it on com5 but it does not read the data and mention
always a number of points error

Does someone has a trick to solve this problem ?

What version of H4 firmware are you using?

The NanoVNA app uses a binary protocol to transfer sweep data. This is
different than the old ASCII protocol that was initially used by the NanoVNA.
If your firmware is over a year old you need to update it.

Just took another look at your console output. Your firmware is over 2 years old so you need to update if you want to use the NanoVNA app

Roger

On Tue, May 31, 2022 at 06:33 AM, Jean-Marie Polard wrote:

I have a problem with the NanoVNA-H(4) and NanoVNA-App

I can connect it on com5 but it does not read the data and mention
always a number of points error

Does someone has a trick to solve this problem ?

What version of H4 firmware are you using?

The NanoVNA app uses a binary protocol to transfer sweep data. This is different than the old ASCII protocol that was initially used by the NanoVNA. If your firmware is over a year old you need to update it.

Roger

On Tue, May 31, 2022 at 07:54 AM, AG6CX wrote:

I’ve always thought of the conventional antenna parameter measurement as the
antenna being in series, i.e., Z load = Zs = Rs + Xs

But could you expand a bit on situations in which you use the parallel model
in general, or specifically to the sketch you posted?

Ed,

Yes most antenna analysis is done using the serial R+/-jX form for impedance. However as Jim Lux points out in another post today ( /g/nanovna-users/message/28231 ) there are cases where the parallel form is useful in antenna measurements.

The intent of my post was to reply to comments by Victor Reijs and G3TXQ (sk) that the S11 mode was not suitable for measuring high impedances. When it comes to the NanoVNA this is not true and actual measurements like the one I posted can be used to prove my point.

Attached is a simplified resistor model showing that R, L and C are present in physical resistors. For low values of R the inductance is the predominate reactive factor but for high values of resistance the parallel capacitive reactance across the resistor needs to be considered. Attached are some plots taken with a test jig designed to measure 0805 components with a 1K resistor mounted in the fixture. Someone new to VNA measurements would look a the R+jX plot and see that the resistance measured looks close to 1000 ohms at very low frequencies (997 ohms) but measures 950 ohms at 250 MHz. The erroneous conclusion is that the 5% error is due to poor measurement capability. However this is not the case because the decrease in R is due to the effect of parallel capacitance. The parallel capacitance is small (less than a pF) but we can measure it and see the actual resistance of the 0805 SMD component by looking at the S11 data in parallel format. The attached plots show that measured R varies from 996 to 1008 ohms over the range of 10 kHz. to 280 MHz. which is quite impressive for a $100 instrument. The capacitance calculated from the parallel reactance X is 0.14 pF across the frequency range.

From the above (and my previous 3K resistor plot) the S11 reflection method has been shown to make reasonably accurate measurement of impedances up to several thousand ohms. That makes it useful for measuring devices like inductors, capacitors and common mode chokes. The other method which is usually suggested for high impedance measurement is the S11 series method. This method assumes 50 ohm CH0 (port 1) and CH1 (port 2) impedance. The NanoVNA varies from 50 ohms over its frequency range and this leads to errors in the measured data. Since the NanoVNA is a two port, one-way device it does not have 12 point error correction to compensate for the deviation from 50 ohms. Owen Duffy has posted several interesting articles on the S21 series method using the NanoVNA on his blog. Measurements are shown to illustrate his points.




My own measurements using the S21 serial method have shown that the quality of the test jig, measurement frequency span and complex impedance range have a significant effect on the accuracy of the results. I tend to use the S11 reflection method most of the time and for cross-checking S21 results.

Roger

Does nanoVNA-Saver work on your machine?
I can see that win7 sp1 is running. To run Saver, I need some things that I described in a pdf file. Link:
Since this was the program before, I didn’t test to see if the NanoVNA App needed the same.

--
Gyula HA3HZ ( )

When dealing with a single feedpoint, working with impedances (and a series formulation of R+Xj) is traditional - it maps well into VSWR, etc.

However, when working with multiple feedpoints, or coupled antennas, sometimes admittances work better. Most method of moments modeling tools (e.g. NEC) build an admittance matrix. So when you have an NT card in NEC, you specify the network parameters in Y parameters. And excitation is specified as voltages - that is, the goal in a NEC type model is to solve for I given Y and V. The currents in the segments are then what is used to compute the radiated and near fields. This is the inverse of an impedance formulation, which would solve for V, given Z and I.

Then, once you've solved the system, one can convert the admittances into Z (or S, for that matter).

Another case where parallel formulations are useful is when you're looking at a unmatched antenna like an AM car radio - The antenna is very short, very reactive and mostly a capacitance. It's feeding a system that is a high input R with a shunt C (stray capacitance and feedline C) - You can use a Thevenin model of the antenna as a Voltage source and a series Z, feeding the parallel combination of Ramp and Ccoax+Camp. This forms a voltage divider and forms the basis of sensitivity calculations. Here, the voltage would typically be the E field * length of antenna.

Roger:

I’ve always thought of the conventional antenna parameter measurement as the antenna being in series, i.e., Z load = Zs = Rs + Xs

Cebik notes that, with respect to modeling and looking at antennas that “parallel … circuits don’t have much until it’s, since they are only the converted counterparts of … series circuits.”

()

He does offer the case of looking at a beta or hairpin match, in which the matching section at the feedpoint is in parallel with the series feedline and load antenna, so clearly there is a place for conversion.

But could you expand a bit on situations in which you use the parallel model in general, or specifically to the sketch you posted?

No criticism implied, I’m just looking for situations where parallel conversion might be advantageous, other than alternative S measurements using Y rather than Z, such as Jeff K6JCA has described below




Looking forward to your thoughts.

73
Ed McCann
AG6CX

Tried this and still just a white screen. I guess it's bricked. Thanks for all the responses.
Perry

Dear,

I have a problem with the NanoVNA-H(4) and NanoVNA-App

I can connect it on com5 but it does not read the data and mention always a number of points error

Does someone has a trick to solve this problem ?

thank you Jean Marie

Hi, out of curiosity I've made a measurement of my nanovna H4 stock RG316 cable (of length 163mm end to end, incl connectors).
NanoVna App shows 158.4mm, while H4 (Measure->Cable) shows almost identical picture as Dislord's one, but with Z0=9k and length 1.6meter (instead of ~Z0=50ohm as on his picture below.). Both measurements done with open end. H4 flashed with today's v1.2.

Thank you for doing this for us
Mike

On 2022-05-30 09:44:-0700, you wrote:

Rich, What is SWR:Linear?

Not sure. I was using the spreadsheet to
1. Confirm that menu items were returning values I expected, so that I could update the manual with meaningful language
2. Explore data relationships.

I provided the spreadsheet in a separate thread so that
1. It would be easier to find, rather than being an offhand reply to a different message
2. Provide a path for those not as familiar with spreadsheets to be able to import data easier, and to see how the complex data is handled by Excel. Many of the formulae are in the user manual posted in the files section, so folks wanting to create their own spreadsheets (for plotting and comparisons, data exploration, etc) can use those equations to process the data once it is in complex form.

Then it's up to users to decide how to use it.

~R~

On Mon, May 30, 2022 at 12:50 AM, tuckvk3cca wrote:

Thanks, just been reading the late G3TXQ articles. Very useful. He said a one
port measurement is no good. Surely if I terminate the choke with a r ohm
resistor , I can measure R + j X that way and subtract to get (R - r) + j X.
Has anybody tried that?

One port S11 measurement on a NanoVNA-H4 gives good results up to several thousand ohms (see attached 3K ohm example). It is better than using the S21 serial method. The S21 serial method does not work that well on a NanoVNA. The reason is that the Ch0 and CH1 impedances are not 50 ohms across a wide range of frequencies and the NanoVNA does not do a 12 point calibration. There have been several discussions in this group about measuring chokes, baluns and impedance using various methods. Lots of good info if you do a group search.

Roger

Rich, What is SWR:Linear?

Roger

I updated this spreadsheet for the convenience of others by rearranging the columns and including instructions in the spreadsheet.

~R~
72/73 de Rich NE1EE
The Dusty Key
On the banks of the Piscataqua

Thanks, Victor!

73,
Costin, YO8RCD

?n lun., 30 mai 2022 la 12:16, Victor Reijs <pe1atn.victor.reijs@...>
a scris:

Alright, thank you!

Best
Fabio

For a choke we want to determine high im[edance values and the one port is
not really good in that (low accuracy). See here for some background:

The Series through is better (method c)


All the best,

Victor

Op ma 30 mei 2022 om 09:50 schreef tuckvk3cca <tuckvk3cca@...>:

Solved : just change line thickness and point size before closing window

Hi all,

I don't know if this has been posted before, but I'll give it a try.
I use the software on my Mac and all seems to run. But when I go to 'Display Setup' and check 'Show lines' the software crashes. The only way to recover and make it possible to start is to edit or delete the NanoVNASaver.ini file. Is there a solution to display lines in stead of dots?

Many thanks,
Alex, PE1EVX

Thanks, just been reading the late G3TXQ articles. Very useful. He said a one port measurement is no good. Surely if I terminate the choke with a r ohm resistor , I can measure R + j X that way and subtract to get (R - r) + j X. Has anybody tried that?