Another case which will result in varying readings is a vertical antenna (e.g for a handheld) which is lacking a ground/counterpoise/ground plane/feedpoint choke; then the measurement system becomes part of the antenna's ground. End fed antennas often have considerable feedline currents which will affect the readings.
Use the VNA in the state it was calibrated in, for antenna work probably best to use the battery and leave the charger disconnected, or add chokes/ferrites etc. You may need ferrites on both feedline and charger cord, it is hard to predict.
You might want to set the VNA down on a nonconductive stool or table for use, to avoid body effects on antenna measurements.
73, Don N2VGU
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Re: NanoVNA - Signal Generator
In some applications a square wave can be beneficial. Many mixers will perform better with a square wave LO than with a sinusoidal one.
73, Don N2VGU
|
Thanks.
How do you explain this:
MFJ: 1.8
NanoVNA not connected to laptop via USB-C: 2.7
Forget about the laptop, the USB-C cable, the NanoVNA Saver app .. but just unplugging/plugging the coax among MFJ/NanaoVNA.
The MFJ is correct; I used it at another site last weekend, and compared the reading to a $10k spectrum analyzer someone used there.
I went through several cycles of calibrating the NanoVNA, all with the same result.
|
When I have this problem it¡¯s usually because I¡¯m getting RF coming back on the shield, I put a couple of clamp on fairite chokes on or coil the coax and I get good readings again. Just an idea.
73 Bill N7OQ
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Show quoted text
On Jun 6, 2022, at 14:45, W0LEV <davearea51a@...> wrote:
?This has been addressed a number of times in this group. If you cal
without the USB cable connected and then connect it for a measurement of
your unknown, this is quite expected. The case of the VNA is "extended" by
the presence of the USB cable and interacts with the unknown, especially if
it is a radiating structure.
Dave - W0LEV
On Mon, Jun 6, 2022 at 12:19 PM Stefan <spommere@...> wrote:
Hi,
I have a MFJ-259B antenna analyzer and now also a NanoVNA-H, along with
the NanoSaver App.
I get inconsistent VSWR readings with both devices:
MFJ: 1.8
NanoVNA not connected to laptop via USB-C: 2.7
NanoVNA connected to laptop via USB-C: 1.1
The VSWR reading on the NanoVNA literally goes from 1.1 to 2.7 when I
unplug the USB-C cable from the NanoVNA.
I went through call calibration steps at least a half dozen times on the
NanoVNA for 50kHz to 900MHz, and for the 40m band (7.0 MHZ - 7.3 MHZ).
Any suggestions as to what value I should actually trust ?
I wonder if I need to calibrate the NanoVNA through the Saver app
separately; based on what I've gathered, it should not be necessary.
Thanks for any advice.
--
*Dave - W?LEV*
*Just Let Darwin Work*
--
Dave - W?LEV
|
This has been addressed a number of times in this group. If you cal
without the USB cable connected and then connect it for a measurement of
your unknown, this is quite expected. The case of the VNA is "extended" by
the presence of the USB cable and interacts with the unknown, especially if
it is a radiating structure.
Dave - W0LEV
toggle quoted message
Show quoted text
On Mon, Jun 6, 2022 at 12:19 PM Stefan <spommere@...> wrote: Hi,
I have a MFJ-259B antenna analyzer and now also a NanoVNA-H, along with
the NanoSaver App.
I get inconsistent VSWR readings with both devices:
MFJ: 1.8
NanoVNA not connected to laptop via USB-C: 2.7
NanoVNA connected to laptop via USB-C: 1.1
The VSWR reading on the NanoVNA literally goes from 1.1 to 2.7 when I
unplug the USB-C cable from the NanoVNA.
I went through call calibration steps at least a half dozen times on the
NanoVNA for 50kHz to 900MHz, and for the 40m band (7.0 MHZ - 7.3 MHZ).
Any suggestions as to what value I should actually trust ?
I wonder if I need to calibrate the NanoVNA through the Saver app
separately; based on what I've gathered, it should not be necessary.
Thanks for any advice.
-- *Dave - W?LEV* *Just Let Darwin Work*
--
Dave - W?LEV
|
Re: Firmware Upgrade What Am I Doing Wrong?
Very happy you were able to resolve your issue73's
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Show quoted text
On Monday, June 6, 2022, 01:44:02 PM EDT, A DeCarmo via groups.io <wce4@...> wrote:
Thanks Chris, finally figure it out it was the driver all the time.
|
Possibly a ground loop thru the USB-C. Try running the laptop from its battery, no recharging PS.
WA0VYU
Sent from the all new AOL app for Android
On Mon, Jun 6, 2022 at 1:19 PM, Stefan<spommere@...> wrote: Hi,
I have a MFJ-259B antenna analyzer and now also a NanoVNA-H, along with the NanoSaver App.
I get inconsistent VSWR readings with both devices:
MFJ: 1.8
NanoVNA not connected to laptop via USB-C: 2.7
NanoVNA connected to laptop via USB-C: 1.1
The VSWR reading on the NanoVNA literally goes from 1.1 to 2.7 when I unplug the USB-C cable from the NanoVNA.?
I went through call calibration steps at least a half dozen times on the NanoVNA for 50kHz to 900MHz, and for the 40m band (7.0 MHZ - 7.3 MHZ).
Any suggestions as to what value I should actually trust ?
I wonder if I need to calibrate the NanoVNA through the Saver app separately; based on what I've gathered, it should not be necessary.
Thanks for any advice.
|
Hi,
I have a MFJ-259B antenna analyzer and now also a NanoVNA-H, along with the NanoSaver App.
I get inconsistent VSWR readings with both devices:
MFJ: 1.8
NanoVNA not connected to laptop via USB-C: 2.7
NanoVNA connected to laptop via USB-C: 1.1
The VSWR reading on the NanoVNA literally goes from 1.1 to 2.7 when I unplug the USB-C cable from the NanoVNA.
I went through call calibration steps at least a half dozen times on the NanoVNA for 50kHz to 900MHz, and for the 40m band (7.0 MHZ - 7.3 MHZ).
Any suggestions as to what value I should actually trust ?
I wonder if I need to calibrate the NanoVNA through the Saver app separately; based on what I've gathered, it should not be necessary.
Thanks for any advice.
|
Re: Firmware Upgrade What Am I Doing Wrong?
Thanks Chris, finally figure it out it was the driver all the time.
|
Re: Firmware Upgrade What Am I Doing Wrong?
Thanks for Replying Fred I am using a NanoVNA-H Finally figure it out it was the driver all the time.
|
Thanks Roger, I will digest your report. THANKS. I am glad that Brian's paper (which I also found some time ago) is valid, accept it looks that the NanoVNA is more accurate than the system he describes in his paper. That is good news (so the theory is corret, but the system accuracy makes the difference). So the Series S21 should perhaps also be better (over larger range) than mentioned in the article... I might look at Brian's and your paper and see if I can derive the Series/Shunt S21 error curves... I though find my |ZseriesS21| results (using NanoVNA-D, version 1.0.64, kernel 4.0.0) worrying... Thanks again for informing me about your paper. All the best, Victor Op ma 6 jun. 2022 om 18:30 schreef Roger Need via groups.io <sailtamarack= [email protected]>:
On Tue, May 31, 2022 at 02:07 PM, Victor Reijs wrote:
It is not me but
or
who derives the accuracy.
Can you provide where they go wrong? The accuracy of any measurement is important and an excellent paper on
this subject was
written by Brian Walker of Copper Mountain Technologies (a VNA
manufacturer).
"Make Accurate Impedance Measurements Using a VNA" available from
This paper has been discussed on groups.io before and has been subject to
misinterpretation
by myself and others. So I contacted the author and he was kind enough to
answer my
questions and send me his spreadsheet for error analysis. The paper goes
into considerable depth on how to calculate the impedance measurement and
an error equation is derived to calculate ¦¤S11(max).
The author then goes on to derive ¦¤S11 for a Copper Mountain Technologies
S5065 VNA which can measure from 9 kHz to 6.5 GHz with a reflection
accuracy (S11) specified to be ¡À0.4 dB for measurements from ?15 to 0 dB.
The curves and charts in his article are all based on THIS specification.
They are NOT applicable to the NanoVNA which has better performance when
used over a much narrower frequency range.
I wrote a technical note that provides more detail on his paper and how it
can be applied to the NanoVNA. I hope you find it informative. It can be
downloaded from my Box account at the link below"
Roger
|
On Tue, May 31, 2022 at 02:07 PM, Victor Reijs wrote: It is not me but
or
who derives the accuracy.
Can you provide where they go wrong? The accuracy of any measurement is important and an excellent paper on this subject was written by Brian Walker of Copper Mountain Technologies (a VNA manufacturer). "Make Accurate Impedance Measurements Using a VNA" available from This paper has been discussed on groups.io before and has been subject to misinterpretation by myself and others. So I contacted the author and he was kind enough to answer my questions and send me his spreadsheet for error analysis. The paper goes into considerable depth on how to calculate the impedance measurement and an error equation is derived to calculate ¦¤S11(max). The author then goes on to derive ¦¤S11 for a Copper Mountain Technologies S5065 VNA which can measure from 9 kHz to 6.5 GHz with a reflection accuracy (S11) specified to be ¡À0.4 dB for measurements from ?15 to 0 dB. The curves and charts in his article are all based on THIS specification. They are NOT applicable to the NanoVNA which has better performance when used over a much narrower frequency range. I wrote a technical note that provides more detail on his paper and how it can be applied to the NanoVNA. I hope you find it informative. It can be downloaded from my Box account at the link below" Roger
|
On 6/6/22 9:15 AM, Costin R wrote: Hi all!
In the following link you can find an interesting use for NanoVNA.
I know there were discussions about using it as a signal generator.
Everyone was referring to the rectangular shape of the signal and the
problems of using this signal.
Adam Rong (BD6CR) successfully tested the device as a local oscillator
using the STIMULUS-CW FREQ function.
I think the article below may be the beginning of many experiments.
If Adam's language is a problem (;-) it is for me too), use Google
Translate.
73!
YO8RCD <> As a LO, the square-wave isn't a problem, since for most mixers, the LO should be driving the mixer into saturation. (that is, the mixer acts as a switch).? It's no different than what's inside the NanoVNA driving the SA612 LO ports. Depending on the mixer, one might need some gain, but if you can get +10dBm out, then driving a +7dBm mixer should be no problem.
|
Hi all!
In the following link you can find an interesting use for NanoVNA.
I know there were discussions about using it as a signal generator.
Everyone was referring to the rectangular shape of the signal and the
problems of using this signal.
Adam Rong (BD6CR) successfully tested the device as a local oscillator
using the STIMULUS-CW FREQ function.
I think the article below may be the beginning of many experiments.
If Adam's language is a problem (;-) it is for me too), use Google
Translate.
73!
YO8RCD <>
|
Re: spreadsheet for importing snp files, Excel 2010
Hi Ed, Well...new day! Raised in the woods...literally...in N Maine. 2-room school. No electricity until I was 10. Traveled quite a bit after 18. Spent a lot of time in Ca, including visiting Sausalito. Lived in SF, N of SF later, then San Clemente, and Oceanside. Now back in New England. Not often to hear of someone from the area, though there are a lot of active hams in New England. We test 5-10 per month, new and upgrades. Your cell ¡°M4¡± states value of RLdB = 35.9176dB I see you are one of those folks who like "smart" quotes...apparently, my email is too dumb to understand them. Sigh. Like me, like my email ;-) Actually L4 in my copy... Small fix. Not necessary...as I posted in the thread, the point of the spreadsheet is just to give folks the tools do as they like. No warranty expressed or implied. Feel free to use it as ye will. ~R~ 72/73 de Rich NE1EE The Dusty Key On the banks of the Piscataqua
|
Thanks Roger for pointing this out. Knowing one's measurement tools is the basic rule here. Thanks for pointing out. I have also checked my NanoVNA. If I measure the Zload of port 2 (using Port 1, so using a calibration Through connection and measuring port2's S11). I get the following |Zload| of port 2: [image: afbeelding.png] This is ok-ish IMHO (variation some 0.1ohm (less than 0.2%). There is a deviation from 50ohm (around 05%), but this could be partly due to inaccuracy calibration Load (measured with DVM: 49.7ohm). I don't think the Zload (|Z| of port2/load) is problematic. If I measure metal resistors (averaged between 300 and 1800kHz) using Reflection and Series S21 I method, I get the below |Z| values. I also give the R values measured with DVM [image: afbeelding.png] [image: afbeelding.png] So indeed |Zrefl| does not deviate much from the DVM value (<2%). The |ZseriesS21| though differs quite a lot (~9%) from DVM value and looks to be proportional to the resistor value. Where is this 9% error coming from? A 9% error is large! I don't think the deviation of the port2 load (Zload) from 50ohm is problematic (only some 0.2%). Looking at the Zsourse (the impedance of port 1): would that not be close to Zload (impedance of port2, I hope/assume...). But that one is compensated using the SOLTI method, or not? I understand the missing of 12-term correction is the other problem (as stated by Owen Duffy: ). Who has a procedure for this? I could not find this on the web (Owen Duffy refers to it, but I don't see a procedure). Something must deviate some 9% from the 'my norm', but what? I tried to simulate this by varying Zo, Zload, Zsource; but I can't find really realistic values to cater for the variation see in ZseriesS21 (I need to bring Zload back to some 40ohm to cater for this 9%, but then some other Z values (|ZseriesS11|) don't match properly [and it is not measured, see above!];-). Any help to understand this is appreciated. Thanks. So at this moment I agree that 2port Series method does not produce good values. All the best, Victor Op di 31 mei 2022 om 23:07 schreef Victor Reijs via groups.io <pe1atn.victor.reijs@...>:
Hello Roger,
Op di 31 mei 2022 om 19:40 schreef Roger Need via groups.io <sailtamarack=
[email protected]>:
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.
It is not me but
or
who derives the accuracy.
Can you provide where they go wrong? That would be very helpful. For me.
Thanks.
All the best,
Victor
|
Re: Firmware > 1.0.53 not working on my H4 (4.2)
#firmware
Hello Roger
Thanks for the answer.
I tested clear config and restart with 1.2.00, no luck. (i reduced the sweep points to 51 and it took "only" about 20 sek for a sweep, but no useful readout connected to my DemoKit 6.5MHz BSF)
Then i saw in the vna beta group, that there is a 1.2.02 version.
I installed it and heureka, it sweeps even faster, than 1.0.53.
I also have a useful signal at S11. (I actually need it as a signal generator to do some tests on my (tr)uSDX 5-band | multimode TRx | 5W | QRP)
I'm happy again ;-)
Thomas
|
Re: spreadsheet for importing snp files, Excel 2010
Hi Ed,
Just returned home...don't have an nVNA handy...
There are 2 questions on the table.
1. What does the H4 show for FORMAT > LINEAR?
ans: LINEAR - Magnitude (absolute value) of Sxy.
That's if I recall correctly.
That's why the Linear col in the spreadsheet calculates | S11 |.
The user manual is an attempt to lay out for folks what the H4 is doing...for example, when I first saw LINEAR, I wondered what that could be. I don't associate the word "linear" with "absolute value", "Euclidean norm", or "p-norm", where p=2. So I took a data set, and, using the same data (not scanning), changed the formats to see what they displayed.
I /think/ that if someone fires up an H4 and sets the display format to LINEAR, they will find it is | S11 |.
If that turns out to be the case, then right or wrong, that's what LINEAR means in an H4.
2. What does "one_port.pdf" say?
Well, to begin with, not the point. The point is to document what the H4 is doing, whether or not it is doing it correctly.
Then..."one_port.pdf" says
Just as for the Return Loss, the VSWR (dimensionless) is calculated from rho...(11)
where 1+rho = 1+| S11 |
seemingly suggesting that rho is the magnitude of S11.
I havna really read the doc...
I welcome discussion...
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Show quoted text
On 2022-06-05 08:22:-0700, you wrote: It ain¡¯t.
Ed McCann
AG6CX
|
On 05/06/2022 18:09, Siegfried Jackstien wrote: hi Roger
a table with ALL of them to compare would be superb
.... aehem ... 7 inch screen size?? what model is that??
dg9bfc sigi For example: JNCRADIO SV4401A - 4.4G VNA WITH 7'' CAPACITIVE TOUCHSCREEN Sysjoint. David GM8ARV -- SatSignal Software - Quality software for you Web: Email: david-taylor@... Twitter: @gm8arv
|
hi Roger
a table with ALL of them to compare would be superb
.... aehem ... 7 inch screen size?? what model is that??
dg9bfc sigi
Am 05.06.2022 um 19:02 schrieb Roger Need via groups.io:
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On Sat, Jun 4, 2022 at 08:28 AM, Vince Loschiavo wrote:
I would like to purchase a later version of the nanoVNA.
Which vendor does everyone recommend that has the latest?
thanks There are many "NanoVNA" products on the market - NanoVNA-H, NanoVNA-H4, NanoVNA-F, LiteVNA, LiteVNA64, LibreVNA, NanoVNA SAA2, NanoVNA-F V2, SV4401A, V2Plus, V2Plus4 and several more....
What is best for you depends on your requirements in terms of budget and specifications.
- standalone or PC required to operate
- maximum frequency of interest
- dynamic range of S11 and S21
- screen size (2.8", 4" or 7")
- connector type (SMA or N connector)
- metal or plastic case
- measurement capability (antenna measurements only or measuring components, filters etc. )
- product support (documentation, manuals, user groups)
There is no table comparing all the products on the market. If you let us know what you want after considering the above we can point you in the right direction.
Roger
|
Donald S Brant Jr
Roger Need
Rich NE1EE
David J Taylor