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Hi,

Is my setup ok ? Is there any monstrous mistakes in my montage ? I'm quite new to the nanoVNA. Well, I am totally new on VNAs themselves. I did not know their exitance 2 months ago ! Well, I want to match my antenna because so far, it is pretty horrible. But, before ordering some matching network component and then screwing everything because I am missing something obvious, I would like someone to point me to the rookie mistakes I could have made.

The project is a LoRa module (902-928MHz) connected to a small antenna mounted on a pcb. The pcb is inside a small polycarbonate box. I have followed the design rules for this antenna from the manufacturer. I have calibrated my nanoVNA-F V2 (from sysjoint) using the supplied calibration set, straight at the S11 connector. My board is inside its final box and mounted on a wood plank that mimic the final location. My board is hooked up to the vna through an RG-174 I had laying around. It is 2 meters exactly. I have added an E-Delay of 10.1ns as per a calculator I found on the Times microwave website. I don't know if there is a bug in the vna's firmware but I had to put 0.66 as the velocity factor in order to make it display 2.00 meters as the cable length. If I put 66 as in 66%, it shows 200 meters. Anyways, I'm not sure if that part is that relevant.

So, by looking at the pictures, does anyone can see some obvious mistakes ?

Thank you so much

Use S21 mode with an amplifier.

People have been using VNAs as radars for years.
The NanoVNA just makes it easier.

Dealing with the big first reflection is tricky. One way is to use a separate cancellation path that is adjusted to null the first reflection. ?That’s what we did for the FINDER victim detection radar.

FINDER: Radar for Locating Disaster Victims ( )
jpl.nasa.gov ( )

( )

You have noted the shortcomings of* ANY* VNA, including those from the "big
boys" at $$$$$. Nothing new, here.

Yes, the VNA deals with impedances. Frequency analysis best be
accomplished using a spectrum analyzer, not a VNA. Time analysis best be
accomplished using an o'scope.

Impedance domain......frequency domain......time domain......

Dave - W?LEV

On Sat, Feb 22, 2025 at 2:47?PM Team-SIM SIM-Mode via groups.io <sim31_team=
[email protected]> wrote:

Hi

We have the impression that the NanoVNA is as an impedance meter, a
Q-meter or a frequency analyzer, while it is only a transmission line
network analyzer, that is to say we have to do with impedances that turn
around 50 Ohm with a SWR that can go to 10:1 max beyond which the
precision loses much of its meaning,

in fact the S11 measurements are made at the base of a physical 50 Ohm
resistive divider bridge, it is sufficiently precise around 50 Ohm but it
loses its precision as we move away from this value, saying very correct
measurements is between 5 and 500 Ohm otherwise the interpretation of the
measurements becomes very compromised,

thus the Z-renormalization should not used to the extrem much from 50 Ohm
and it will be tedious as we are moving away from 50 Ohm, so renormalizing
the Z to 440 Ohm is really at the limit of validity of these ingenious
calculation methods which facilitate the measurements with the greatest
simplicity and least chance of implementation errors.

so with this good results, we are already Happy .

73's Nizar

--

*Dave - W?LEV*


--
Dave - W?LEV

Indeed, it is optimized for 50 ohms, but I don’t know that I’d say the precision loses much of its meaning as you get away from that.
Can you quantify your assertion?

Ultimately, the accuracy is determined by the uncertainty of the raw I/Q measurements, which is around 1 part in a few thousand, and then whatever that does when calculating reflection coefficients. At big mismatches the signal into the reflected port of the bridge is large, so the SNR is high (70-80 dB?) which is 1 part in 10,000.

As they say in school, show your work - give an example of a measurement uncertainty with an unknown near 50 ohms, and then one of one near, say, 500 ohms, and 5k.

The Copper Mountain folks have an article on various ways to measure Z, and there’s differences in how the errors stack up whether you’re doing series or shunt techniques. That might be a place to start.

I'm starting to think that adding the washers, (in other words increasing the space between the NanoVNA's front/top cover and the touchscreen just a teeny bit) solved the start-up problem as well, because when I press the menu on-off/toggle control while I turn the power on, I get the same blank screen as described above.

Hi

We have the impression that the NanoVNA is as an impedance meter, a Q-meter or a frequency analyzer, while it is only a transmission line network analyzer, that is to say we have to do with impedances that turn around 50 Ohm with a SWR that can go to 10:1 max beyond which the precision loses much of its meaning,

in fact the S11 measurements are made at the base of a physical 50 Ohm resistive divider bridge, it is sufficiently precise around 50 Ohm but it loses its precision as we move away from this value, saying very correct measurements is between 5 and 500 Ohm otherwise the interpretation of the measurements becomes very compromised,

thus the Z-renormalization should not used to the extrem much from 50 Ohm and it will be tedious as we are moving away from 50 Ohm, so renormalizing the Z to 440 Ohm is really at the limit of validity of these ingenious calculation methods which facilitate the measurements with the greatest simplicity and least chance of implementation errors.

so with this good results, we are already Happy .

73's Nizar

On 22/02/2025 09:42, werthercaro via groups.io wrote:

-=-=-=-=-=-=-=-=-=-=-=-

Thanks for the reminder. Upgraded OK and working on an H4/MS.

David
--
SatSignal Software - Quality software for you
Web:
Email: davidtaylor@...
BlueSky: @gm8arv.bsky.social, Twitter: @gm8arv

My version appears a bit different.

73

Jon, VU2JO

On Fri, Feb 21, 2025 at 10:08?PM Barry Leonard KN4JRF via groups.io <w9jbl=
[email protected]> wrote:

Fixed the jumpy menu (kinda). Put two 0.7mm/0.027in flat washers as thin
spacers on rt. side on NanoVNA (see foto) to keep cover from pressing on
touch screen.

I have done a few surface mount repairs, and I have a tiny Oryx 6-watt iron and some tweezers :)
But I can't locate the videos you refer to. I've tried searching on Youtube for every combination of nanoVNA and rf input, burnout, etc.

In the meantime I have ordered the same model H4 (with excellent reviews) from Aliexpress again, $61 with tax and shipping.

Fixed the jumpy menu (kinda). Put two 0.7mm/0.027in flat washers as thin spacers on rt. side on NanoVNA (see foto) to keep cover from pressing on touch screen.

Nizar,

No I don’t believe Port Z function is in the latest version but check for yourself.

Hi Roger Need

Please what is the latest version reference of Dislord modded NANoVNA-App windows program ? If It does have the Z-renormalized function ? Or Z0-renormalized function ??

H4 firmware gives me satisfaction, what we have to expecte more with Nanovna-App ??

Thanks
73s Nizar

Normally this destroys some surface mount components. Unless you have
experience replacing surface mount components a new unit is the best
option. Also. There are several YouTube videos about this situation.

On Thu, Feb 20, 2025, 10:29?PM Charles, WB3JOK/0 via groups.io
<charlesmorris800@...> wrote:

Today I was doing two things at once, and unfortunately transmitted 400W
of SSB into my inverted-V while my nanoVNA H4 was still hooked up to my
OCFD antenna! Although they are perpendicular, they're not far enough apart
to save the front end on the H4 :(

So - how difficult is this to repair? Are the parts expensive, or too
small to replace by hand (i.e. should I just buy another)?
Thanks for any helpful hints.
-Charles

I would assume significant and maybe subtle damage and replace it.

Chuck
K4TZO

On Thu, Feb 20, 2025 at 10:29?PM Charles, WB3JOK/0 via groups.io
<charlesmorris800@...> wrote:

Today I was doing two things at once, and unfortunately transmitted 400W
of SSB into my inverted-V while my nanoVNA H4 was still hooked up to my
OCFD antenna! Although they are perpendicular, they're not far enough apart
to save the front end on the H4 :(

So - how difficult is this to repair? Are the parts expensive, or too
small to replace by hand (i.e. should I just buy another)?
Thanks for any helpful hints.
-Charles

--
Chuck Cole ?K4TZO

Today I was doing two things at once, and unfortunately transmitted 400W of SSB into my inverted-V while my nanoVNA H4 was still hooked up to my OCFD antenna! Although they are perpendicular, they're not far enough apart to save the front end on the H4 :(

So - how difficult is this to repair? Are the parts expensive, or too small to replace by hand (i.e. should I just buy another)?
Thanks for any helpful hints.
-Charles

On Thu, Feb 20, 2025 at 11:57 AM, diyer wrote:

What are the alternative to vnasaver? I got it running fine but discovered
that it is painfully slow and it doesn't mark frequency line in small
increments.

What I want is something that is fast as the standalone vna so I can do some
what ifs regarding antenna tuning for various frequencies and save the results
as well. Maybe VNA_QT does that?

VNA-QT is not a program for your NanoVNA. NanoVNA-QT (VNA View) is the native software for the NanoVNA V2 Plus4 and VNA6000 series.

There are some very old apps for the NanoVNA like NanoVNA Sharp and NanoVNA Mod3 but they were very basic. NanoVNA App is the one I use and it has very nice features. DiSlord and Owen Duffy have made some nice improvements since the original author OneOfEleven stopped working on the project.

NanoVNA Saver scans reasonably fast if you set the frequency range to your band of interest and then calibrate. Here is a video I made for you showing me matching an antenna for the 20M band using a manual tuner. You can see the SWR, Return Loss and Smith Chart change as I rotate the knobs.

Patience, my boy, patience.

You can widen the RBW and VBW for faster scans. But you will lose noise
floor. You can also decrease the number of segments you wish to scan to
increase speed, but you will lose resolution. You can force more rapid
sweep, but you will lose both peak accuracy and reliability and
resolution. You can also try NANOVNA APP as an alternative. The
trade-offs I've mentioned are basic physics and really can't be overridden
without the compromises I noted.

Patience, my boy, patience.

Dave - W?LEV



<>
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On Thu, Feb 20, 2025 at 7:57?PM diyer via groups.io <m240zz=
[email protected]> wrote:

What are the alternative to vnasaver? I got it running fine but
discovered that it is painfully slow and it doesn't mark frequency line in
small increments.

What I want is something that is fast as the standalone vna so I can do
some what ifs regarding antenna tuning for various frequencies and save the
results as well. Maybe VNA_QT does that?

My surfing on VNA_QT seems to indicate that I would have to reflash my 5
year old VNA. Plus I don't know if its faster or how easily one can store
output files. I've had reasonable luck reflashing other devices so I think
I could do it w/o bricking but if VNA_QT isn't faster then its not worth
the effort.

I know I shouldn't complain, after all its all free.
73

--

*Dave - W?LEV*


--
Dave - W?LEV

What are the alternative to vnasaver? I got it running fine but discovered that it is painfully slow and it doesn't mark frequency line in small increments.

What I want is something that is fast as the standalone vna so I can do some what ifs regarding antenna tuning for various frequencies and save the results as well. Maybe VNA_QT does that?

My surfing on VNA_QT seems to indicate that I would have to reflash my 5 year old VNA. Plus I don't know if its faster or how easily one can store output files. I've had reasonable luck reflashing other devices so I think I could do it w/o bricking but if VNA_QT isn't faster then its not worth the effort.

I know I shouldn't complain, after all its all free.
73

Here's an update on the SVHFS 2025 Conference;
Deadline for papers has been extended to March 17
Conference & hotel registration is open; details are in the attached file.


Thanks,
Robin Midgett K4IDC