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Hi Roger,

This is an (educational) presentation, not a paper. My talks are always for radioamateurs and this formula is best known. This triggers the audience to listen before it gets more 'complicated' :-)

If you look into this presentation a few pages more, the complex impedances are explained and shown. Even the 40+j30 and SWR=2.

73

Arie PA3A

Op 4-8-2022 om 18:30 schreef Roger Need via groups.io:

Hi,

I have the same HW as you and update the FW regularly with the latest DiSlord versions. His project is very active and brings a lot of improvements:

It supports NanoVNA-H (default) as well as -H4 (config option). You can easily switch back to your 20211230 version if you're not happy.
There's no risk of bricking your device, just open it, connect the two pins of P1 and switch on -> DFU mode where you can load a new FW.

Or add one wire to enter DFU mode when you hold the jog switch down during power on:
/g/nanovna-users/message/10026

If you want to see the 3.4 schematics just go to Hugen's place, he has also the newer HW revisions with SD card, that is supported by DiSlord's FW.


HTH Martin

Hi all, in April 2020 I purchased a NanoVNA H with the following characteristics:

Based on edy555 design
Licensed under GPL see https: // etc ect
Version 0.4.5-1-gfbbceca
Build time: Dec 26 2019 - 19:32:31
HW version 3.4.
Then I updated the firmware to version 0.4.5-4 of 1/18/2020. From that moment on I have not updated because I noticed that there are many Hardware versions, many specific firmware and I was afraid to make it a brick. These days I wanted to check if there was any new firmware and looking a bit on the web both on the Hugen portal and on our group, I saw that the latest firmware are NanoVNA-H-SI_20210130.dfu and NanoVNA-H-SI_20211230.dfu . Of these latest firmware I have seen that there are 2 versions, the MS and the SI, which are respectively for the SI5351 cpu (that of mine) and the MS5351.
I first installed the NanoVNA-H-SI_20210130.dfu firmware very easily (having already installed dfu drivers and software because I often update Tyni SA with DFUSE 3.0.6.)
I noticed that the characters got bigger and there were other functions. Then I wanted to install the latest firmware: NanoVNA-H-SI_20211230.dfu
I noticed that there are even more functions and settings even the date and time and the possibility of using an SD card.
Considering that my version is the NanoVNA H 3.4 with 2.8 "display, I would really like to know which is the most suitable and compatible firmware. I would not mind leaving the latter NanoVNA-H-SI_20211230.dfu installed because it is really complete. Rather, where can I find a guide that explains how they are set up and what are the usable functions it has in addition (example I use sd card. Many thanks for the help

Hello
I follow your discussion with interest but my language is not English - thank you Google. If you could avoid using acronyms such as "ADC". What does it mean ?
Could you develop a little more what follows

----o----
One other thing..
The "raw measurement" that the NanoVNA makes is essentially a filtered sum of 48 samples. The raw adc samples are probably about 1 part in 10^4 (call it 1E-4 fractional uncertainty) so 48 samples will be sqrt(N) better, or 1.4E-5. (ignoring arithmetic precision).

That's voltage, not power, relative to full scale.

In reality, the input signal isn't full scale, it's more like 0.1 full scale or 0.05 full scale, so the uncertainty is about 0.1%

The reflection coefficient is calculated as the algebraic combination of two of those measurements, so the uncertainty is roughly doubled (0.2%)
----o----
- thank you
--
F1AMM (Fran?ois)

Yes of course, the ohmic, or DC resistance itself in the context of the antenna impedance measurement?is a far less significant contributor than the reactance's; capacitive, and inductive. But, in terms of the device?calibration the DC components are all we use. So, I was wondering that how flawed (or not) any subsequent?analysis might be as a result of using a 50 ohm calibrator that was somewhat less or greater than 50 ohms.?I suspect not much at all.

You are thinking in DC, switch to AC + calibration plane, fringing
capacitance etc.

On Fri, 5 Aug 2022 at 05:08, Chris Gardner via groups.io <seaman98=
[email protected]> wrote:

Pondering a simple question relating to SMA calibration devices as in
those that are generally supplied with a newly purchased Nano VNA as an
example. Open is Open, that is obvious. The connector simply shields
the the female connector from any outside interference during calibration.
The short is obvious as well, 0 (Zero Ohms) resistive load. But, more to
the point, my biggest concern is with the supposedly 50 Ohm resistive
calibration load. I have 3 such devices from various sources, and none are
precisely 50 Ohms. My most recent purchase has a calibration sticker
enclosed in the kit indicating the 50 ohm load is 48.9 ohms. I confirmed
that value with my DVM. Would that be considered adequate, or good enough.
How significant does that difference in the ohmic resistance become in the
final sweep product. Of course assuming I am calibrating the VNA at the end
of the feed line just before the actual antenna.
On Thursday, August 4, 2022 at 09:36:02 PM EDT, Donald S Brant Jr <
dsbrantjr@...> wrote:

I got my cal kit from Dr. David Kirkby kirkbymicrowave.co.uk. It
includes not only extensive characterization data but also optionally
verification standards which will allow you to check the quality of your
calibrations.
73, Don N2VGU

Pondering a simple question relating to SMA calibration devices as in those that are generally supplied with a?newly purchased Nano VNA as an example. Open is Open, that is obvious. The connector simply shields the?the female connector from any outside interference during calibration. The short is obvious as well, 0 (Zero Ohms)?resistive load. But, more to the point, my biggest concern is with the supposedly 50 Ohm resistive calibration?load. I have 3 such devices from various sources, and none are precisely 50 Ohms. My most recent purchase?has a calibration sticker enclosed in the kit indicating the 50 ohm load is 48.9 ohms. I confirmed that value with?my DVM. Would that be considered adequate, or good enough. How significant does that difference in the ohmic?resistance become in the final sweep product. Of course assuming I am calibrating the VNA at the end of the?feed line just before the actual antenna.

I got my cal kit from Dr. David Kirkby kirkbymicrowave.co.uk. It includes not only extensive characterization data but also optionally verification standards which will allow you to check the quality of your calibrations.
73, Don N2VGU

On Thu, Aug 4, 2022 at 10:24 AM, 0root wrote:

What do you guys make of these calibration boards?

Accurate enough to give a result with <3% differences?

That is NOT a calibration board. That is a DEMO board. Those are good enough to show a VNA newbie: What would a parallel resonant circuit look like on a VNA? What would a series resonant circuit look like? What would a low pass filter look like? What would a high pass filter look like? What would an attenuator look like? That's all they are good for. They aren't calibration standards by any stretch of the imagination.

The various NanoVNAs are fine for ham/hobbyist use. I will agree with John Gord that your best investment is probably education. W2AEW has a number of good YouTube videos, as does W0QE:

On 8/4/22 3:57 PM, W0LEV wrote:

Jim, the NANOVNAs I contend are highly useful for us amateurs and "top
level" professional applications and CERTAINLY for education. However, I
use mine where I can not carry the (100-lb.) 8753C with S-Parameter Test
Set. That and the price point is where the NANOVNAs shine for the amateur
and professional. Of course, Keysite has offered a portable VNA as does
R&S, but the price point(s) keep us amateurs away. Fortunately, at one
time (pre-Carley), HP encouraged dumpster dipping. For those of us who
practiced our skills on the hobby as well as on the job, that was quite a
priviledge!!!

Sure - the original question was about possible other VNAs with better performance.

I cited the Keysight FieldFox (an "inexpensive" analyzer in Keysight land :) ) as I interested in showing how they give plots of uncertainty vs test conditions.

I think one could produce a similar set of plots for the NanoVNA and that might be interesting.

OOOOoops,........That's W?LEV, not WLEV. For some reason I have to wait a
few seconds to release the "ALT" button for the "zero" in ASCCI code to
register. Who knows.......it's a digital world........

Dave - W?LEV

On Thu, Aug 4, 2022 at 10:57 PM David Eckhardt <davearea51a@...>
wrote:

Jim, the NANOVNAs I contend are highly useful for us amateurs and "top
level" professional applications and CERTAINLY for education. However, I
use mine where I can not carry the (100-lb.) 8753C with S-Parameter Test
Set. That and the price point is where the NANOVNAs shine for the amateur
and professional. Of course, Keysite has offered a portable VNA as does
R&S, but the price point(s) keep us amateurs away. Fortunately, at one
time (pre-Carley), HP encouraged dumpster dipping. For those of us who
practiced our skills on the hobby as well as on the job, that was quite a
priviledge!!!

Dave - WLEV

On Thu, Aug 4, 2022 at 5:50 PM Jim Lux <jimlux@...> wrote:

On 8/3/22 4:38 PM, 0root via groups.io wrote:

Hey all, first post here.

I currently own and love the nanovna-h and h4, I was sure to buy them

from the alibaba store zeenko as this is apparantly hugens chosen
manufacturer.

However, if I wanted to get more precision - specifically in the areas

of Return Loss / VSWR and attenuation readings - what would be the next
device up to get - within the region of $100 - $2000 and no higher...

I see alot of siglent stuff, but the reviews are not too appetizing

One other thing..
The "raw measurement" that the NanoVNA makes is essentially a filtered
sum of 48 samples. The raw adc samples are probably about 1 part in 10^4
(call it 1E-4 fractional uncertainty) so 48 samples will be sqrt(N)
better, or 1.4E-5. (ignoring arithmetic precision).

That's voltage, not power, relative to full scale.

In reality, the input signal isn't full scale, it's more like 0.1 full
scale or 0.05 full scale, so the uncertainty is about 0.1%

The reflection coefficient is calculated as the algebraic combination of
two of those measurements, so the uncertainty is roughly doubled (0.2%)

So that really sets your accuracy - especially with a big signal (e.g.
the reflection of a short or open) - with a good load, the accuracy is
less, because reflection power is less, so the uncertainty of that
measurement is poorer. If the reflected power is -40 dB, then the
signal to noise of the measurement is 1/100th, so instead of a 0.1%
uncertainty, it's more like 10%



More expensive analyzers will have better SNR, from a larger stimulus
signal, a lower input noise floor, and a narrower detection bandwidth
(which reduces the noise).

--
*Dave - W?LEV*
*Just Let Darwin Work*

--
*Dave - W?LEV*
*Just Let Darwin Work*


--
Dave - W?LEV

Jim, the NANOVNAs I contend are highly useful for us amateurs and "top
level" professional applications and CERTAINLY for education. However, I
use mine where I can not carry the (100-lb.) 8753C with S-Parameter Test
Set. That and the price point is where the NANOVNAs shine for the amateur
and professional. Of course, Keysite has offered a portable VNA as does
R&S, but the price point(s) keep us amateurs away. Fortunately, at one
time (pre-Carley), HP encouraged dumpster dipping. For those of us who
practiced our skills on the hobby as well as on the job, that was quite a
priviledge!!!

Dave - WLEV

--
Dave - W?LEV

Yet another reason to become familiar with the complex representation of
the impedance! Oh,.....yes,......AND the Smith Chart.

Dave - W?LEV

On Thu, Aug 4, 2022 at 8:43 PM Maynard Wright, P. E., W6PAP <w6pap@...>
wrote:

This constant SWR circle is certainly a useful exposition of the concept
and is very
nicely done. Having the Smith Chart display on the nanoVNA can be very
helpful even
if you retrieve data numerically. It can validate the way that you
interpret the data.

It's important to note that SWR = Zt / Zo is correct only when Xt and Xo
both equal
zero. For most cases of interest to amateur radio Xo will always be zero,
but Xt will
most often not be zero, so the simplified equation is of limited use.

73,

Maynard
W6PAP



On Thursday, August 04, 2022 09:15:26 AM Roger Need via groups.io wrote:

On Wed, Aug 3, 2022 at 06:52 PM, Kenneth Hendrickson wrote:

On both charts, 25+j0 and 100+j0 need to be swapped. They are wrong as
labeled.

Thanks for the correction. I put these together quickly and should have
proofread them for errors. Here are the corrected versions showing

several

complex impedance values that all result in an SWR of 2.

--
*Dave - W?LEV*
*Just Let Darwin Work*


--
Dave - W?LEV

On Thu, Aug 4, 2022 at 01:43 PM, Maynard Wright, P. E., W6PAP wrote:

It's important to note that SWR = Zt / Zo is correct only when Xt and Xo both > equal
zero. For most cases of interest to amateur radio Xo will always be zero, but > Xt will
most often not be zero, so the simplified equation is of limited use.

I agree that the simple formula is of little use in real world use and it cause more confusion than it is worth.

Also....
SWR = Zt/Zo for Zt >= Zo and Xt and Xo both = 0 Example: Zt = 100 + j0 and Z0 = 50 + j0 then SWR = 100/50 = 2
SWR = Zo/Zt for Zt <= Zo and Xt and Xo both = 0 Example: Zt = 25 + j0 and Z0 = 50 + j0 then SWR = 50/25 = 2

Roger

This constant SWR circle is certainly a useful exposition of the concept and is very
nicely done. Having the Smith Chart display on the nanoVNA can be very helpful even
if you retrieve data numerically. It can validate the way that you interpret the data.

It's important to note that SWR = Zt / Zo is correct only when Xt and Xo both equal
zero. For most cases of interest to amateur radio Xo will always be zero, but Xt will
most often not be zero, so the simplified equation is of limited use.

73,

Maynard
W6PAP

On 8/4/22 10:24 AM, 0root via groups.io wrote:

What do you guys make of these calibration boards?

Accurate enough to give a result with <3% differences?

As noted elsewhere, the basic measurement uncertainty is around 1%, so if your cal standard uncertainty is 1%, then you're in the right ballpark.

But it *really* depends on what you're measuring.

Consider measuring a 40 dB attenuator, and you care about S21 accuracy. The NanoVNA can easily do <1% measurement uncertainty of a 0dB attenuator, but the uncertainty of a signal that is 1/100th the amplitude will be bigger. The signal is smaller, but the noise is the same.

If you look at uncertainty curves for Keysight VNAs, you can see how the uncertainty varies as a function of the return loss (S11) or attenuation (S21)


See page 15

You can see that for S21, at lower frequencies, the uncertainty in magnitude is 0.1 dB (about 1% for linear magnitude) for "low loss" components, but as the loss gets bigger (-70dB) the uncertainty starts to climb. That's what the NanoVNA can do, but it will start to climb at lower attenuations.

It's even more obvious in the S11 (Reflection Uncertainty). For a big mismatch (== lots of reflected power), the uncertainty is low (fractions of a dB), but as the load gets to be higher quality, the uncertainty climbs. A load with a -40dB S11 has an uncertainty of 3-4 dB (40%).

That's with -15dBm stimulus (comparable to the NanoVNA) 10 Hz IF bandwidth (500 times narrower than NanoVNA - that improves the SNR by 27 dB). So if the FieldFox does pretty good to -50dB S21, then the NanoVNA can do almost as well up to -25 dB, but then it will start to degrade.


The FieldFox also probably has a *better* calibration algorithm (more terms, etc), so that helps too.



keysight even offers a calculator for determining the uncertainties - it might be usable with other VNAs

On 8/3/22 4:38 PM, 0root via groups.io wrote:

Hey all, first post here.
I currently own and love the nanovna-h and h4, I was sure to buy them from the alibaba store zeenko as this is apparantly hugens chosen manufacturer.
However, if I wanted to get more precision - specifically in the areas of Return Loss / VSWR and attenuation readings - what would be the next device up to get - within the region of $100 - $2000 and no higher...
I see alot of siglent stuff, but the reviews are not too appetizing

One other thing..
The "raw measurement" that the NanoVNA makes is essentially a filtered sum of 48 samples. The raw adc samples are probably about 1 part in 10^4 (call it 1E-4 fractional uncertainty) so 48 samples will be sqrt(N) better, or 1.4E-5. (ignoring arithmetic precision).

That's voltage, not power, relative to full scale.

In reality, the input signal isn't full scale, it's more like 0.1 full scale or 0.05 full scale, so the uncertainty is about 0.1%

The reflection coefficient is calculated as the algebraic combination of two of those measurements, so the uncertainty is roughly doubled (0.2%)

So that really sets your accuracy - especially with a big signal (e.g. the reflection of a short or open) - with a good load, the accuracy is less, because reflection power is less, so the uncertainty of that measurement is poorer. If the reflected power is -40 dB, then the signal to noise of the measurement is 1/100th, so instead of a 0.1% uncertainty, it's more like 10%



More expensive analyzers will have better SNR, from a larger stimulus signal, a lower input noise floor, and a narrower detection bandwidth (which reduces the noise).

What do you guys make of these calibration boards?



Accurate enough to give a result with <3% differences?

On 8/4/22 9:39 AM, 0root via groups.io wrote:

Siegfried Jackstien - Thanks for the recommendation, I will research these.
John Gord - Re maintaining a consistent length between O, S, L - the three now provided with the nanoVNA are just RPSMA caps... therefore they should meet this criteria?
Thanks for the details on the article, Should be able to find it.
Donald S Brant Jr - Thanks for the recommendation, I'll research LibreVNA
Also, you're right re making your own...a matter of confidence vs doubt... I guess buying multiple kits then testing them all to see the alignment may help put faith in the chosen kit?

The problem is you're in the "observer with two watches, which one is correct" scenario.

Unless you have access to a (much) better measurement tool, you won't know if it's the cal standards or something else.

Another thing to remember is that it's "knowledge" of the cal standard that's important. Your cal standard for a load might range from 45 to 55 ohms with some reactive components. As long as you KNOW what the impedance is at each frequency, that can be incorporated into the calibration process (not inside the NanoVNA, but in some other software).

The basic instrument assumes perfect standards, and that simplifies the calculation of the calibration terms used. But that's not strictly necessary.

W0LEV - Thats good to hear... I have heard that its not worth upgrading as the nanoVNAs are good enough... I guess this is looking more like finding a better calibration kit to use with the N.V