I've been analyzing Touchstone files Rudy Severns, N6LF, has recorded with his NanoVNA-H4. The magnitude of S11 is greater than 1 for many files. For example, after calibration right at the VNA connector, |S11| was 1.0007 maximum for the open cal part itself. For the short the maximum was 1.0005. For both, |S11| > 1 for all 401 points from 0.1 to 50 MHz.
The images show calculated permittivity and conductivity for a ground probe with the rods in air. The image with most of the points missing used uncorrected data. The other image is for normalized data where |S11| = 1 maximum.
Although normalization solves the problem for my software, I'm curious why |S11| is ever > 1.
Brian
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@All
Thank you for the valuable input.
@Roger , for the nice links to schematic & More specific groups.
@gfmucci for the "Static warning"
@Jim & Zack for the "Don't connect the FT-991A directly to the VNA" :-)
Ps: Jim i finally got a HP 5065A ... :-)
@Dave For that "invaluable tip, about the coax , and the finger/screwdriver" .. I didn't think about this one.
Rgds
Carsten
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And as far as static goes: Remember that any coax is, by design, low loss and can store a sizable amount of energy as a cylindrical capacitor. So, I always make a practice of "shorting" any coax I connect to test equipment by firmly placing my (somewhat damp) finger over the end of the coax before connecting to anything. After a good lightning storm, you can get quite an "awakening" with this practice, but it saves expensive and sensitive test equipment. Dave - W?LEV On Mon, Jun 13, 2022 at 6:06 PM gfmucci via groups.io <gfmucci= [email protected]> wrote: "What is the most likely way that beginners kill their VNA ?"
Static buildup especially in dry climates. I had one DOA and the vendor
said static buildup killed it.
-- *Dave - W?LEV* *Just Let Darwin Work* -- Dave - W?LEV
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I have been really careful about estimating power out of an amp. I have an
HP 435B power meter with an 8484A head. Maximum power to the head is
supposed to be 10 microwatts (-20 dBm). I carefully calculate the
attenuation needed to keep the input to the head within this range. If I
estimate a power amp could be putting out 10 watts, I'll use 70 dB of
attenuation.
Same for the NanoVNA. I have used it to adjust VHF preamps that could
possibly put out +20 dBm with a gain of 20 dB. So I'll put 30 dB of
attenuation on the input. So far I haven't burned out either the HP power
meter or the NanoVNA.
Zack W9SZ
toggle quoted message
Show quoted text
On Mon, Jun 13, 2022 at 1:09 PM Jim Lux <jim@...> wrote: On 6/13/22 11:06 AM, gfmucci via groups.io wrote:
"What is the most likely way that beginners kill their VNA ?"
Static buildup especially in dry climates. I had one DOA and the vendor said static buildup killed it.
The second most likely is "transmitting into it", or, more properly,
making S21 measurements on a small amplifier that has output power
bigger than the VNA can take. That 20dB gain block, driven with -10 to 0
dBm puts out +10 to +20, which is more than the VNA can take.
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On 6/13/22 11:06 AM, gfmucci via groups.io wrote: "What is the most likely way that beginners kill their VNA ?"
Static buildup especially in dry climates. I had one DOA and the vendor said static buildup killed it.
The second most likely is "transmitting into it", or, more properly, making S21 measurements on a small amplifier that has output power bigger than the VNA can take. That 20dB gain block, driven with -10 to 0 dBm puts out +10 to +20, which is more than the VNA can take.
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"What is the most likely way that beginners kill their VNA ?"
Static buildup especially in dry climates. I had one DOA and the vendor said static buildup killed it.
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Carsten, Here is a link to the manufacturers Web site for your NanoVNA 2 Plus 4 Firmware, instruction manuals and PC software available there. There are two groups dedicated to your VNA model and you will get more specific help there. /g/NanoVNAV2/topics/g/NanoVNA-V2/topicsRoger
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Hello Goup
Old Ham here , but have never played with DIY antennas before , and have never had a HF Station.
I have just gotten my first HF Ham station (FT-991A) , as i have "some" room in the summerhouse garden for maybe a 20..25 meter wire.
Now i want to start playing with "Wire antennas" on 3..50MHz bands, more specifically an EHFW to begin with , as a Dipole layout does not really fit.
I have bought on Aliexpress: 1 x "Original NanoVNA V2 Plus4 4 inch 4GHz":
Expect it to arrive within a month or so.
Since it's Ali .. I hope i get a "Real Original" , not a "CN reduced Clone" .. Lets see.
Any URL to a Schematic of the above VNA ??
When i get it , i see 3 steps to begin with (Focus on antenna measurements) :
1: What firmware to load on the VNA (An URL would be nice)
2: What PC program to use if i want to "Pull out data" (An URL would be nice)
I would prefer Linux (Ubuntu/Mint) , but i have Win10 also if that enhances the experience for a beginner.
3: How to get started with antenna measurements - the tough part i guess .....
When i see a Smith Chart , I always think it's either a "Childs drawing" or a "Vortex from StarTreck".
I just got the Absolute_Beginner_Guide_NanoVNA_v1_6.pdf from the files section , and also some relevant smith chart info from there.
But a "Quick guide, if it exists" just to get started would be invaluable.
Ohh ... A Do & DON'T guide would be nice too :-)
I'd expect for starters , to just feed the Antenna from the VNA, when measuring with the VNA.
What is the most likely way that beginners kill their VNA ?
TIA
Carsten F
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Re: Using a nanoVNA as a passive receiver
Yes, the TinySA is a far better tool for your proposed application.
However, the NANOVNA can be used to measure the isolation between two
antennas. Use it in a 2-terminal transmission measurement setup. One
antenna connects to port zero and the other antenna connects to port one.
You will be able to directly measure the isolation between the two
antennas.
Dave - W?LEV
toggle quoted message
Show quoted text
On Sun, Jun 12, 2022 at 9:53 PM Evan Hand <elhandjr@...> wrote: It should work, though I would terminate the Ch0 port with the 50ohm cap.
A better tool is the TinySA. It is about $60 in the US.
TinySA.org
-- *Dave - W?LEV* *Just Let Darwin Work*
--
Dave - W?LEV
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Re: Using a nanoVNA as a passive receiver
It should work, though I would terminate the Ch0 port with the 50ohm cap.
A better tool is the TinySA. It is about $60 in the US.
TinySA.org
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Using a nanoVNA as a passive receiver
Hello.? Can anyone tell me if it's possible to use a nanoVNA such that it emits no signal and only operates as a receiver?? I want to try to detect and measure what is being emitted by an emitting antenna, using a simple single-turn loop antenna as detector. Placing that simple antenna within the active field of the emitting antenna, attaching the simple antenna to?the transmission (Ch1) port, and leaving the excitation/reflection (Ch0) port unattached comes to mind as a possibility, but I haven't tried it yet.? Thanks.? I just want to determine the frequency of the emitted field.? Thanks
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Re: adding Bluetooth HC-06 connection to plain - H hardware
#bluetooth
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On Sun, Jun 12, 2022 at 07:20 AM, @Alex1961 wrote:
Sorry, my english is not good. I need software to cinfig the nano vna.
Thank you.
Try NanoVNA Saver >> Roger
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Sorry, my english is not good. I need software to cinfig the nano vna.
Thank you.
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Re: 2port measurement determining Zdut with S11 and S21
Thanks Stan for this feedback. Anyfeedback is very welcome.
I put click-on ferrites (25mm long) on port1, port2 and USB cables, they
have (in my setup) no significant effect on the measured S21 (or S11)
2port series through measurements.
Anyway, all feedback is very welcome. Every question/query/remark can help
to pinpoint things more precisely. Thanks.
All the best,
Victor
Op zo 12 jun. 2022 om 05:31 schreef Stan Dye <standye@...>:
toggle quoted message
Show quoted text
Victor, I notice that in these examples you are using the nanoVNA with the
saver software, connected to a computer via USB cable.
When I do a similar setup, I note that the USB cable to the computer can
significantly affect the measurement at HF frequencies. I found that I
had to use a high quality cable and put ferrite beads on it to decouple
that RF path. You may wish to experiment with that to see if it gives you
better stability in your results.
On Sat, Jun 11, 2022, 4:22 PM Victor Reijs <pe1atn.victor.reijs@...>
wrote:
I forgot to add that the NanoVNA measured Impedance (based on the S21 (or
S11) 2port series through):
[image: afbeelding.png]
matches quite nicely the theoretical simulation of a choke:
[image: afbeelding.png]
<the theoretical simulation got one parameter (stray capacitance of the
choke, not of the testing gear!) which was derived by matching the peak in
the simulation with the peak in the measured S21 curve>
I think I am more or less understanding what/how is measured with the
NanoVNA. Will try to make a web page out of that.
All the best,
Victor
Op za 11 jun. 2022 om 08:32 schreef Victor Reijs via groups.io
<pe1atn.victor.reijs@...>:
Hello Roger,
Using Series though, the NanoVNA measures both a S11 and S21 (for that
configuration, which I [of course] calibrated). The link I gave (
), calculates the Zdut using
these Sx1 from the 2port series through measurement. In the case of the
resistive DUTs the S11 measured with 2 port (red blue dotted) is almost
identical with the S11 measured with 1 port (orange dotted). The same I see
with the toroid DUT.
But I am not able to map the Zdut calculated with the S21 (green dashed;
measured in the series through 2 port).
So the Zdut (Zx) using with 2port series through and S11 based is different
from Zdut (Zx) using (the same) 2 port series through and S21 based. So all
stray capacitances, etc are the same (which I see part of the DUT).
All the best,
Victor
Op za 11 jun. 2022 om 07:26 schreef Roger Need via groups.io
<sailtamarack=
[email protected]>:
Victor,
I am not sure how you are measuring the DUT using S11 reflection and S21
series methods.
You have to measure them with the correct reference plane calibration
and
this usually requires two different test jigs. What are you using
for
S11
and S21 test jigs? Attached is one I use for S11 up to 30 MHz. I
tack
solder the DUT as shown. My example uses an inductor but you can
solder
the leads to your choke. The second one I built into a box and it
works
well too. I posted my S21 series jig in the last topic
Roger
|
Re: 2port measurement determining Zdut with S11 and S21
Victor, I notice that in these examples you are using the nanoVNA with the saver software, connected to a computer via USB cable. When I do a similar setup, I note that the USB cable to the computer can significantly affect the measurement at HF frequencies. I found that I had to use a high quality cable and put ferrite beads on it to decouple that RF path. You may wish to experiment with that to see if it gives you better stability in your results. On Sat, Jun 11, 2022, 4:22 PM Victor Reijs <pe1atn.victor.reijs@...> wrote: I forgot to add that the NanoVNA measured Impedance (based on the S21 (or
S11) 2port series through):
[image: afbeelding.png]
matches quite nicely the theoretical simulation of a choke:
[image: afbeelding.png]
<the theoretical simulation got one parameter (stray capacitance of the
choke, not of the testing gear!) which was derived by matching the peak in
the simulation with the peak in the measured S21 curve>
I think I am more or less understanding what/how is measured with the
NanoVNA. Will try to make a web page out of that.
All the best,
Victor
Op za 11 jun. 2022 om 08:32 schreef Victor Reijs via groups.io
<pe1atn.victor.reijs@...>:
Hello Roger,
Using Series though, the NanoVNA measures both a S11 and S21 (for that
configuration, which I [of course] calibrated). The link I gave (
), calculates the Zdut using
these Sx1 from the 2port series through measurement. In the case of the
resistive DUTs the S11 measured with 2 port (red blue dotted) is almost
identical with the S11 measured with 1 port (orange dotted). The same I see
with the toroid DUT.
But I am not able to map the Zdut calculated with the S21 (green dashed;
measured in the series through 2 port).
So the Zdut (Zx) using with 2port series through and S11 based is different
from Zdut (Zx) using (the same) 2 port series through and S21 based. So all
stray capacitances, etc are the same (which I see part of the DUT).
All the best,
Victor
Op za 11 jun. 2022 om 07:26 schreef Roger Need via groups.io
<sailtamarack=
[email protected]>:
Victor,
I am not sure how you are measuring the DUT using S11 reflection and S21
series methods.
You have to measure them with the correct reference plane calibration
and
this usually requires two different test jigs. What are you using for S11
and S21 test jigs? Attached is one I use for S11 up to 30 MHz. I tack
solder the DUT as shown. My example uses an inductor but you can
solder
the leads to your choke. The second one I built into a box and it
works
well too. I posted my S21 series jig in the last topic
Roger
|
Re: adding Bluetooth HC-06 connection to plain - H hardware
#bluetooth
Hi Vaclav,
Please type ¡°P3 uart¡± into the Search box in the upper right to help to identify this board level change.
Larry
AC9OX
|
Re: 2port measurement determining Zdut with S11 and S21
I forgot to add that the NanoVNA measured Impedance (based on the S21 (or S11) 2port series through): [image: afbeelding.png] matches quite nicely the theoretical simulation of a choke: [image: afbeelding.png] <the theoretical simulation got one parameter (stray capacitance of the choke, not of the testing gear!) which was derived by matching the peak in the simulation with the peak in the measured S21 curve> I think I am more or less understanding what/how is measured with the NanoVNA. Will try to make a web page out of that. All the best, Victor Op za 11 jun. 2022 om 08:32 schreef Victor Reijs via groups.io <pe1atn.victor.reijs@...>:
Hello Roger,
Using Series though, the NanoVNA measures both a S11 and S21 (for that
configuration, which I [of course] calibrated). The link I gave (
), calculates the Zdut using
these Sx1 from the 2port series through measurement. In the case of the
resistive DUTs the S11 measured with 2 port (red blue dotted) is almost
identical with the S11 measured with 1 port (orange dotted). The same I see
with the toroid DUT.
But I am not able to map the Zdut calculated with the S21 (green dashed;
measured in the series through 2 port).
So the Zdut (Zx) using with 2port series through and S11 based is different
from Zdut (Zx) using (the same) 2 port series through and S21 based. So all
stray capacitances, etc are the same (which I see part of the DUT).
All the best,
Victor
Op za 11 jun. 2022 om 07:26 schreef Roger Need via groups.io
<sailtamarack=
[email protected]>:
Victor,
I am not sure how you are measuring the DUT using S11 reflection and S21
series methods.
You have to measure them with the correct reference plane calibration and
this usually requires two different test jigs. What are you using for S11
and S21 test jigs? Attached is one I use for S11 up to 30 MHz. I tack
solder the DUT as shown. My example uses an inductor but you can solder
the leads to your choke. The second one I built into a box and it works
well too. I posted my S21 series jig in the last topic
Roger
|
Re: Off subject - nanoVNA forum no longer on Facebook
#nanovna
Many years ago I made a BIG mistake by signing up with my real name. I get unwanted , unsolicited
e-mail addressed to that mail box.
I am opinionated and I do not pussy foot around issue , I tell how I feel.
If you watched George Carlin "shell shock " monologue you will know
that giving a same issue fancy name does not fix the issue.
Unfortunately a lot of "contributors" in forums concentrate on format
and not on resolving issuers.
And there is time honored management policy - to resolve an issue - fire the complainer...
end of rant
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Carsten F (OZ1FTG)
gfmucci
Roger Need
tjackson382000
Larry McElhiney
