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On 8/13/21 8:42 AM, Syd via groups.io wrote:

When calibrating the NanoVNA, one plugs in the open, short, & dummy load (O, S, L) directly into the NanoVNA; hence, the calibration plane is at the unit itself. Since I'm using connector cables to test DUTs, wouldn't it make more sense to plug in these (O, S, L) to the end of the test cable and make that the calibration plane more accurate?

Yes.

The isolation and through calibration steps need to be done only when measuring DUTs throughput response such as filters and such. So the through cal step should be done using both measuring cables connected together in series I assume.

Yes

The isolation cal step is a little confusing. I assume no cables need to be attached to the NanoVNA. Then there should be either a dummy load or an attenuator connected to the S11 port. And then the isolation cal should be done.

at the end of the cable, if you're using them.

I just found, in the Files section of this forum, this document

"NanoVNA RF CalibrationConsiderations and Procedure-v1.1" (you can tell I'm rather new to this forum and am still learning about all of it's possibilities)

and after an initial perusal of this document, it looks like all my questions are answered here! I did notice that the calibration procedure looks like it is being done at the ends of the test cables as we discussed. Also I see that it mentions using 2 50 ohm dummy loads in this document for the isolation CAL! Luckily, I just bought a spare dummy load to go with the Nano.
73
wt1v

You can connect the nanoVNA to the mac using the latest version of SimSmith.

See



for an overview

Intro toSimSmith is here:

youtube.com/ae6ty

You can download SimSmith here:

ae6ty.com/Smith_Charts.html

ward

Syd,
Yes you should calibrate at the end of the cable, not the VNA connectors. solation iswhen a load is attached to both inputs at the same time o r if you have only one load, just to ch1. Only the through measurement connects the two inputs together.
Gary
W9TD

When calibrating the NanoVNA, one plugs in the open, short, & dummy load (O, S, L) directly into the NanoVNA; hence, the calibration plane is at the unit itself. Since I'm using connector cables to test DUTs, wouldn't it make more sense to plug in these (O, S, L) to the end of the test cable and make that the calibration plane more accurate? The isolation and through calibration steps need to be done only when measuring DUTs throughput response such as filters and such. So the through cal step should be done using both measuring cables connected together in series I assume. The isolation cal step is a little confusing. I assume no cables need to be attached to the NanoVNA. Then there should be either a dummy load or an attenuator connected to the S11 port. And then the isolation cal should be done.
syd/wt1v

On 8/13/21 8:12 AM, David Eckhardt wrote:

When connecting any length of coax to any sensitive measurement instrument,
I ALWAYS first grab the end of the coax and effectively short the end with
a finger or hand. If there has been a recent lightning storm, you might be
surprised and the discharge might surprise you in an undesirable manner.
The cylindrical capacitor that makes up the coaxial cable can hold a charge
for a very long time.

Blowing dust, snow, or rain, are even more of a charging hazard than the field from a passing thunderstorm.? Continuous charging. It charges until something breaks down, so you get a buzz or continuous clicking. A sort of relaxation oscillator.

Fooling around with this kit the other day I noticed 2 things. The smith chart, when calibrated from 1M - 900M, gave a not so smooth graph for the various smith charts. How do I fix this resolution problem? Maybe a smaller calibration range? Also, when measuring, using the logmax traces for the various filters, all looked OK except for the BSF and BPF filters. Their frequencies were off from what was shown on the demo board. So I'm guessing that this cheap board has it's limitations and I should just except the results and ignore the posted resonant points.
syd/wt1v

On 8/13/21 8:06 AM, Syd via groups.io wrote:

I saw a video about the dangers of using the nanoVNA by connecting to the antenna coax: static buildup on the coax. So I guess one way around this is to measure right at the antenna. The nano is portable. But that still leaves the coax so I suppose that I should short out the coax before measuring it. Any other measures/precautions about measuring out doors antennas?
syd/wt1v

Static will build up on the antenna, not just the coax. Or even the stuff sitting on the bench.? The ESD sensitivity varies substantially among the various small VNAs. Some have resistor bridges/pads right on the inputs.? Others have MMIC switches. The latter are more sensitive.

The other thing to worry about is nearby transmitters inducing sufficient power into your antenna to cause problems.


I suppose, one could check for any of these by measuring the AC voltage across a 50 ohm load hooked up to the UUT, with a simple (cheap, sacrificeable) diode probe. A 1N4001 and 0.01 uF would probably work, since you're looking for "volts" not "microvolts". A $10 DMM, diode, etc.

When connecting any length of coax to any sensitive measurement instrument,
I ALWAYS first grab the end of the coax and effectively short the end with
a finger or hand. If there has been a recent lightning storm, you might be
surprised and the discharge might surprise you in an undesirable manner.
The cylindrical capacitor that makes up the coaxial cable can hold a charge
for a very long time.

Dave - W?LEV

On Fri, Aug 13, 2021 at 3:06 PM Syd via groups.io <nhuq1@...>
wrote:

I saw a video about the dangers of using the nanoVNA by connecting to the
antenna coax: static buildup on the coax. So I guess one way around this
is to measure right at the antenna. The nano is portable. But that still
leaves the coax so I suppose that I should short out the coax before
measuring it. Any other measures/precautions about measuring out doors
antennas?
syd/wt1v

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

I saw a video about the dangers of using the nanoVNA by connecting to the antenna coax: static buildup on the coax. So I guess one way around this is to measure right at the antenna. The nano is portable. But that still leaves the coax so I suppose that I should short out the coax before measuring it. Any other measures/precautions about measuring out doors antennas?
syd/wt1v

Andy - I just updated my Mac configuration to interface with both my NanoVNA/NanoVANH4 and old miniVNA Tiny. Once you've installed Python you can either use "Homebrew" or MacPorts to load the app. I chose Homebrew and now have both Nanos talking to my Mac (High Sierra). Done my way you simply fire up Terminal, change the directory to point to the Python script and issue a Python command and up she comes, works like a champ.

You can start here to get an idea of what's involved.

Here's the info I followed from that site:

1. Install Homebrew from <> (This will ask for your password)

/bin/bash -c "$(curl -fsSL )"

2. Python :

brew install python

3. Pip :<br/>
Download the get-pip.py file and run it to install pip

curl -o get-pip.py
python3 get-pip.py

4. NanoVNASaver Installation : <br/>
clone the source code to the nanovna-saver folder

git clone
cd nanovna-saver

5. Install local pip packages

python3 -m pip install .

6. Run nanovna-saver in the nanovna-saver folder by:

python3 nanovna-saver.py

Hope this helps!

Dino KL?S

Hi All,

Yes, let us all practice respect and tolerance. We come from many backgrounds and levels, and what is great about this group is that we can all learn from each other, and help each other.

Like many technical fields, our field uses a technical jargon which takes ordinary words from our everyday vocabulary, like "port", and attaches to it a specific technical definition. For insiders, this is very convenient and time saving, and we take it for granted. But for neophytes, or simply those who have not been schooled in the jargon, the jargon can be a barrier.

So, for the specific case in point, in circuit theory jargon, a "port" is defined as two connection points to a circuit. For many circuits, it is convenient to define various pairs of connection points as "ports". For many circuits, it is convenient to define only two connection points, and to call this circuit a "1-port" circuit. In many other circuits, it is convenient to defines two pairs of connection points, i.e. 2 ports. Often it is convenient to think of one of them as an input, and the other as an output, but in theory there is no fundamental difference. (In practice, you wouldn't want to excite a power amplifier 2-port at its output!). And in other circuits, it is convenient to designate multiple ports. The nanoVNA allows us to characterize 1-port and 2-port circuits, as the "device under test" (DUT). These two designated points are connected by the shield and central conductor of the SMA coaxial connectors on the nanoVNA.

Hope this helps!

Regards,
Ray
4X1RB

From the home of
Prof. Emeritus Raymond (Reuven) Boxman
School of Electrical Engineering
Tel Aviv University
Cell: ???? +972 544 634 217

CEO Clear Wave Ltd.? ?????????????
Scientific Writing Courses: ???????

Andy, you wrote:

‘ Doesn’t that phrase “1 port device” suggest a single input? ‘

A port has two terminals (signal and reference).

If you are attempting to determine the inductance of a component, a shunt connection between the signal terminal (coax center terminal) and the reference terminal (coax connector body) will get you what you are after.

While you will get some measured s-parameters if you don’t have the reference terminal connected they won’t be correct.

Regards,
Ray WB6TPU

On 8/12/21 5:15 PM, Andrew Kurtz via groups.io wrote:

Here is a quote from P. 14 of the Absolute Beginner’s Guide to NanoVNA found at your site:
"When measuring one port devices, such as an antenna or individual
components, the VNA transmits a signal of known magnitude and frequency from it's
Port 1 into the DUT and measures magnitude and phase of the reflected signal from the
DUT on the same port, VNA Port 1.”
Doesn’t that phrase “1 port device” suggest a single input? My antenna has a single wire going outside; where would I find some other signal to attach to the outer conductor of the small SMA on the VNA? Please don’t reply if you want to tell me I am an idiot and still not help me out.

Andy

This is a classic question on "wire" antennas (think a whip on an HT - the shield on the coax connector goes nowhere).? "the other wire" is there, it's just not at the connector. It's in the stray capacitance of the measurement device to your hand, bench, or surroundings.

In the case of classic "long wire" antennas, often there is a separate connection to a ground rod (or ground radials, or a cold water pipe).. but lots and lots of radios (such as the Nano spectrum analyzer) have the "ground" as "capacitance to surroundings".


It's what makes measuring performance of such antennas challenging - the person (or fixture) holding the radio is part of the antenna.

On 8/12/21 5:08 PM, Andrew Kurtz via groups.io wrote:

OK, I will ignore the rectum who likes to insult and bluster without adding an iota of value to the conversation. I have attached a single alligator clip to the pin of CH0 and to one end of an inductor. I can put a second alligator clip to the pin of CH1 and to the other end of the coil, or I don’t have to. Either way, a signal goes into the inductor from CH0 and is reflected, and the nanoVNA correctly reports the inductance as part of the Smith chart and correctly shows that transmission to CH1 falls off as frequency rises. I believe it is working well, because I calibrated it carefully. There is nothing on the outer conductor of either CH0 or CH1. Do you think I would have better or more confidence results if I attached something to the outer conductor? I don’t even see anything that I could attach there from my coil…

Andy

Sure, it works. the "shield" connection is via the PWB.? You *might* see a difference if you ran a piece of wire from connector shield to connector shield that is parallel with your inductor and test jig. (because forcing the current to flow "around" the loop increases the inductance slightly).? And, of course, calibration is a bit iffy - that is, doing the cal establishes a "calibration plane" at some place, and that assumes that all the currents are flowing "outside" the plane.



S11 should be the inductor in series with the 50 ohm termination at CH1.

S21 is the series combination of the 50 ohm source, the inductor, feeding the 50 ohm load.

Andy,
You are doing it right as the outer conductor is connected through the nanoVNA. The way I do it though is to mount two SMA jacks on a piece of single-sided PCB and have two short wires with alligator clips to the center pins of the connectors. There are other ways to connect components to be measured to the nanoVNA. You can just connect them across ch0 or you can connect them across a connection between ch0 and ch1.
Gary
W9TD

Over what frequency and targeted value of inductance are you measuring? If
you just want the inductance, it would be appropriate to connect the
inductor across the source port, Channel 0, only. One end of the inductor
goes to the center conductor of Ch 0 and the other end of the inductor goes
to the backshell of that connector. The inductance should be relatively
constant with frequency until you approach self resonance of the inductor.
Then it should dip close to zero, and above self resonance, become
capacitive. No real need to connect the inductor between the source port
(Ch 0) and the sink or receive port (Ch 1).

Dave - W?LEV

On Fri, Aug 13, 2021 at 12:08 AM Andrew Kurtz via groups.io <adkurtz=
[email protected]> wrote:

OK, I will ignore the rectum who likes to insult and bluster without
adding an iota of value to the conversation. I have attached a single
alligator clip to the pin of CH0 and to one end of an inductor. I can put
a second alligator clip to the pin of CH1 and to the other end of the coil,
or I don’t have to. Either way, a signal goes into the inductor from CH0
and is reflected, and the nanoVNA correctly reports the inductance as part
of the Smith chart and correctly shows that transmission to CH1 falls off
as frequency rises. I believe it is working well, because I calibrated it
carefully. There is nothing on the outer conductor of either CH0 or CH1.
Do you think I would have better or more confidence results if I attached
something to the outer conductor? I don’t even see anything that I could
attach there from my coil…

Andy

On Aug 12, 2021, at 1:57 PM, David Eckhardt <davearea51a@...>

wrote:

Simple circuit theory taught in HS physics, and even some HS algebra
classes, teach this concept!! This is even hands-on demonstrated to

grade

schoolers in the Fort Collins, Colorado Museum of Science and Discovery.
Yes, grade schoolers!

OK, no more roasting and flaming, but certainly our present educational
system has fallen flat on its face!!

Dave - W?LEV

On Thu, Aug 12, 2021 at 5:49 PM G8DQX list <list@...> wrote:

Andy,

please forgive me suggesting that the below is a truly bizarre
interpretation. For all practical purposes anything connected to an SMA
connector implicitly requires two connections: a) a coaxial outer, and
b) a coaxial inner. If the coaxial outer is not connected, then the
return path from the inner pin is pretty much a matter of good, more
probably bad, luck, written undefined for short.

Always use a coax connection to whatever it is one is trying to measure,
even if using a special test fixture, such as when looking at chokes or
crystals. Then all the current flow paths are well-defined.

HTH, 73, Stay Safe,

Robin, G8DQX

On 12/08/2021 16:25, Andrew Kurtz via groups.io wrote:

All discussions of the NanoVNA suggest that the pin on the SMA

connector

attached to channel 0 is the only connection needed to look at

reflection

(S11).

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

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

Here is a quote from P. 14 of the Absolute Beginner’s Guide to NanoVNA found at your site:
"When measuring one port devices, such as an antenna or individual
components, the VNA transmits a signal of known magnitude and frequency from it's
Port 1 into the DUT and measures magnitude and phase of the reflected signal from the
DUT on the same port, VNA Port 1.”
Doesn’t that phrase “1 port device” suggest a single input? My antenna has a single wire going outside; where would I find some other signal to attach to the outer conductor of the small SMA on the VNA? Please don’t reply if you want to tell me I am an idiot and still not help me out.

Andy

OK, I will ignore the rectum who likes to insult and bluster without adding an iota of value to the conversation. I have attached a single alligator clip to the pin of CH0 and to one end of an inductor. I can put a second alligator clip to the pin of CH1 and to the other end of the coil, or I don’t have to. Either way, a signal goes into the inductor from CH0 and is reflected, and the nanoVNA correctly reports the inductance as part of the Smith chart and correctly shows that transmission to CH1 falls off as frequency rises. I believe it is working well, because I calibrated it carefully. There is nothing on the outer conductor of either CH0 or CH1. Do you think I would have better or more confidence results if I attached something to the outer conductor? I don’t even see anything that I could attach there from my coil…

Andy

From that link to Diligent link in post #8119:

"LabVIEW Home Edition has now been replaced by the free LabVIEW Community Edition from National Instruments!
Learn more about the Community Edition at

Ted, KX4OM