开云体育

Thank you all. I finally had time to return to this subject. After installing newest Nanosaver and calibrating I started to get better results. PC software wants negative numbers, so I added -760ps. You can see results in the screen capture.
One thing, S11 is positive at some frequencies.

Barry:

Nice job !

1.Would have liked to see some reference to the Sark-110,

2. A slide or two on measuring Common Mode Current chokes would be quite instructive, given widespread interest in measuring attenuation of CMC in dB and conversion to impedance offered by the devices

3. Most VNA presentations I have seen overlook the case of trying to measure resonance and impedance parameters of simple doublet fed with ladderline, and how to handle the calibration and input of the ladderline to the VNA.

These would be terrific topics to include if you have the time.

Keep up the good work.

Ed McCann
AG6CX

On 10/25/20 6:57 AM, Barry Feierman wrote:

Hello Nano VNA users
I am working on a Power Point presentation of the Nano VNA as an antenna analyzer for local ham radio clubs.
I am rather new to the VNA vocabulary and have only played with my own Nano VNA for about three months now.
So... I am a real rookie with this gadget, and not an EE.
I posted my presentation in the FILES section of this group but as a PDF file. It's about 90 slides, and 9 MB now so it is not a small file.

Mostly pictures, which is great.


90 slides is way too many for a 1 hour presentation - What I would do is distill your main presentation down to about 30 slides, then push the remainder into "backup" at the end (I assume you're distributing the persentation in some way, so people can look at it, or if you need it to answer a specific question).

For instance, I'd shrink all the pictures of the various antenna analyzers and put them all on one page, maybe in roughly chronological order, showing where it started, and where it is now.

slides 6-12 can be compressed to one slide, showing maybe two lines of progression - antenna analyzers getting smarter, and VNAs getting smaller

Similarly, on slides 34, 35, 36, you could put all three plots on the same slide, to show the comparison of ways of looking at resonance.

That way you're not flipping a new slide every 15-30 seconds, and having someone say "could you go back please".


Just a couple of style things - if you have a choice of line types, and you've got two traces on a plot, make one dashed and one solid, etc. so that a) if someone is colorblind they can tell which is which, or b)if someone prints it black and white. You might be stuck there if the plots are coming from some tool that you don't have control over line style. In that case, a label on the line or near the line with an arrow helps.

Also a legend on the plots, if they have more than one trace, would be useful, on slide 38, which trace is real, which is imaginary? It's not obvious that they're on different Y axes either. In journals, what they do is put a big arrow close to the line, pointing left or right to the correct axis. On that particular graph, since you're talking about where the reactance is zero, put a different color/pattern line across the plot at X=0, and then you can draw a circle around the two intersections.

Finally - slide/page numbers are really handy, so someone in the audience can say "on slide 77...."

Yes, you have the right idea(s). The 45 degree point is unique as it represents the special
case where the frequency which is swept in this example from 1 Hz to 1 MHz, is 1 kHz.

At 1 kHz the voltage across the R and the voltage across the C are the same. The phase
of the voltage lags the current by 45 degrees. The result is the V across the R and the C
are 0.707 V at an angle of 45 degrees. There is some trig involved here but the end result
is the cosine of 45deg x 0.707 results is 0.5V across each element. The sum total is the
input voltage which is 1 V. That V1 generator is an AC source of 1 V peak and it is
instructed to sweep from 1 Hz to 1MHz (1e6) with 10 steps per octave. Sorry, I should
have chosen something more meaningful! By the way, this program is a FREE download,
LTSPICE and is well worth the effort to get, install on your computer and learn how to use.

Anyway, understanding the little RC circuit is worthwhile. Considering it has just 2 parts
there is quite a bit going on here! Think about what happens when the frequency goes down
towards DC and what happens as it approaches 1 MHz. Its all about the relation between the
phase of the voltage and the current in this series circuit.

Yes, so this 1 kHz point is unique as the voltages across each circuit element are the same
and the power at the output is reduced by 3 dB. And you got it, this is the so called -3dB down
point. This is one of the keys that leads to this notion of BANDWIDTH.

Next step. I have to think how to grow this to a tuned circuit by adding a SECOND energy
storage element and a discussion on the term... resonance.

Took a cursory look. You might want to add a section on
how the VNAs measure (basic bridge explanation, Wheatstone bridge etc)
and to emphasize that VNAs measure only voltage and phase and calculate
the rest.

The following photos have been uploaded to the nanoVNA Saver plot from WB4HXE album of the [email protected] group.

• OCF.png

By: Carey Fisher

Looks good! Maybe show charts showing all bands of a multiband antenna like
your 80/40 trapped dipole. Attached is a nanoVNA-Saver plot of my 80-10 OCF
dipole.
73, Carey, WB4HXE

(I'll also upload the plot file to the files section in case it gets
stripped.)

On Sun, Oct 25, 2020 at 9:54 AM [email protected] Notification <
[email protected]> wrote:

The following files have been uploaded to the Files area of the
[email protected] group.

- /Antenna Analyzers Oct 24.pdf
</g/nanovna-users/files/Antenna%20Analyzers%20Oct%2024.pdf>

*By:* Barry Feierman

*Description:*
I am working on a PPT presentation of the NANO VNA for local ham radio
clubs, so am including my draft here for anyone to comment. This is posted
here as a PDF file. TU for suggestions or corrections de Barry k3eui
amateur radio call Phila area

--
Carey Fisher
careyfisher@...

On Sun, Oct 25, 2020 at 02:00 AM, alan victor wrote:

Congratulations Andrea for beginning to get you head wrapped around some of
these ideas!

Actually I've been mumbling for years about facts I took for granted, as far as LC networks are concerned. But NanoVNA is forcing me to go deep inside those facts to gain a greater level of awareness. :-I

Lets take baby steps on this bandwidth concept. Sure others can add their
spin to this.

That's a good idea in order to supply information really tailored to my precise lack of knowledge.

Bandwidth is a term which addresses the frequency response of a circuit.

If your circuit consisted of just resistors, for example a voltage divider,
shown below, circuit 1,
the frequency response in not very interesting. It is flat. That is to say the
relation
between the output voltage and the input voltage is constant. For equal R's,
this
constant would be 1/2.

Now to make this a bit more interesting, we need to replace one of these
resistors with an energy
storage element. Either an inductor or a capacitor will do. Depending on its
location and the type
of energy storage element, we can realize a low pass or a high pass frequency
response. Lets look at circuit 2.

You will note that while input voltage is constant 1 V, the output is also 1
V,
until the AC frequency is 1 kHz. The response is LOW PASS, and an interesting
point that we observe is that the output voltage is at 0.707 V at 1 kHz. This
frequency point,
where the voltage across the capacitor is split equally split with that across
the resistor is defined
as the BANDWIDTH of this RC circuit. Recall, the voltages across the R and C
VECTOR
ADD as the phase shift between V and I in this little series circuit is 45
degress at 1 kHz. We see NO such
phase shift in circuit 1.

Key point of all this.... In order to address the idea of BANDWIDTH we must
introduce
an energy storage element.

How are we at this point?

Just for the sake of precision and verification:

* I assume 2 is the peak-to-peak voltage, 1 is the peak voltage and 1 / √2 = 0.707 is the voltage corresponding to half of the power of the original signal (-3dB point). The thin dotted blue curve in the second diagram refers simply to the
peak-to-peak voltage (it's qualitatively the same as the continuous blue curve, but it is scaled). I hope you can confirm.
* I cannot tell right away where precisely does that 45 degrees come from, but I can overlook this now, being contented with is already obvious: voltage across and current through a capacitor cannot have the same phase if the signal is not
constant in time.
* I'm pretending I didn't notice that still mysterious ".ac oct 10 1 1e6" label... ;-)

Unless unforeseen misunderstandings occurred, then I may sum up: so far, so good. :-)

I do appreciate your effort in explaining such facts. I'm doing my best to deserve this, apart from simply telling THANK YOU! ;-)


A.

Good morning.



If you are a rookie, I am a newborn. I think I'll go warm up my bottle and have a look at your .PDF. I hope it answers more questions than it creates!



Mike – KD5KC -- El Paso -- Texas.



The canyons are calling, colorful and deep. But I have promises to keep.

And miles to go still in my Jeep... And miles to go still in my Jeep...







ADVENTURE: The respectful pursuit of trouble.

Thank you Barry! Your presentation has helped clear some of the fog. What a great tool those nanoVNAs are.


From: [email protected] Notification<mailto:[email protected]>
Sent: Sunday, October 25, 2020 9:54 AM
To: [email protected]<mailto:[email protected]>
Subject: [nanovna-users] File /Antenna Analyzers Oct 24.pdf uploaded #file-notice


The following files have been uploaded to the Files area of the [email protected] group.

* /Antenna Analyzers Oct 24.pdf </g/nanovna-users/files/Antenna%20Analyzers%20Oct%2024.pdf>

By: Barry Feierman

Description:
I am working on a PPT presentation of the NANO VNA for local ham radio clubs, so am including my draft here for anyone to comment. This is posted here as a PDF file. TU for suggestions or corrections de Barry k3eui amateur radio call Phila area

Hello Nano VNA users
I am working on a Power Point presentation of the Nano VNA as an antenna analyzer for local ham radio clubs.
I am rather new to the VNA vocabulary and have only played with my own Nano VNA for about three months now.
So... I am a real rookie with this gadget, and not an EE.

I posted my presentation in the FILES section of this group but as a PDF file. It's about 90 slides, and 9 MB now so it is not a small file.

I am hoping to use some or most of these slides in a one hour presentation on the Nano VNA, so if you have any corrections of comments, I would appreciate hearing from you directly at
k3euibarry - at - gmail.com
Barry Feierman, amateur call K3EUI
Phila region

Looks excellent to me.

You might mention the demo board for training.

The following files have been uploaded to the Files area of the [email protected] group.

• /Antenna Analyzers Oct 24.pdf

By: Barry Feierman

Description:
I am working on a PPT presentation of the NANO VNA for local ham radio clubs, so am including my draft here for anyone to comment. This is posted here as a PDF file. TU for suggestions or corrections de Barry k3eui amateur radio call Phila area

The SAA2 uses the st32f103 and internally, it is flashed using the same dfu process as the original Nanovna.
So yes, it holds true for that unit as well but of course the FW is not interchangeable between the two models.?
The other day, I demonstrated to a friend how pulling the usb cable out in the middle of an update will corrupt the flash and then immediately placing the unit back into boot mode and uploading the flash again completely restored everything.?
Now, with that said, if you're paranoid about the processor going into a weird state, buy a USB STLink dongle so you can push anything into the processor, including manipulating fuse bits and other really low level stuff.? They are available online for about $3.?


On Sun, 25 Oct 2020 at 8:54 AM, AllassoPraise<allassopraise@...> wrote: >> Adding to what Larry wrote and since unfounded fears of "bricking" seem to come up regularly...etc

Does also this stand true for the SAA2N?? From what I understand that
unit uses a different hardware architecture than the predecessors.

Adding to what Larry wrote and since unfounded fears of "bricking" seem to come up regularly...etc

Does also this stand true for the SAA2N? From what I understand that
unit uses a different hardware architecture than the predecessors.


On 10/25/20, Christian Zietz <czietz@...> wrote:

Adding to what Larry wrote and since unfounded fears of "bricking" seem to
come up regularly: Bridging the BOOT and VDD pins, conveniently located next
to each other on the PCB, and powering up the device will force the NanoVNA
into boot mode where you can flash a new firmware via USB using the usual
utilities. This boot mode is hardwired in the STM32 CPU meaning that you
cannot accidentally erase or disable it. Hence, you don't have to worry
about bricking your NanoVNA during a firmware upgrade.

Regards
Christian

Adding to what Larry wrote and since unfounded fears of "bricking" seem to come up regularly: Bridging the BOOT and VDD pins, conveniently located next to each other on the PCB, and powering up the device will force the NanoVNA into boot mode where you can flash a new firmware via USB using the usual utilities. This boot mode is hardwired in the STM32 CPU meaning that you cannot accidentally erase or disable it. Hence, you don't have to worry about bricking your NanoVNA during a firmware upgrade.

Regards
Christian

Hi Karl,
Updating the Nanovna is not a challenge after your first try ;)
You cannot brick the unit either. It appears you have a late 2019 model but that's ok as all the original units up to and including the H version all use the H firmware.?
Please browse through the forum Wiki and view a few YouTube videos that show the flashing process and you'll be a pro in no time.?
If you're good at soldering SMT parts, you can refer to the schematic of the latest H (link in Wiki) and change the resistors? yourself.?
There are many good scripts that are attached to messages that will help with writing a screen capture Util. Do a search of messages from Herb and Kristo and you'll find them. Read up the doc I wrote on searching the forum. It's the 1st link in the Wiki.?
Good luck!
Larry


On Sun, 25 Oct 2020 at 7:30 AM, Karl Jan Skontorp<karl.jan.skontorp@...> wrote: I have got a 2.8" NanoVNA, but I'm not sure what version and which firmware to use. Some help regardin unit identification and firmware version would be very appreciated! Thanks in advance!
Here is the unit:
It's a black sandwich type with the text in white. On the back there are symbols for the scrollwheel, a curve, on/off battery and USB symbol. The bottom line: "NanoVNA Very Tiny Handheld Vector Network Analyzer" uan at the right, the usuak "TX, REFL TRANS RX" and arrwos.
On the PCB I can see "NanoVNA H v3.2"
The splash-screen at startup shows: "gen111.taobao.com".
If sending a console command ("info") I get the following information:
Kernel:? ? ? 4.0.0
Compiler:? ? GCC 5.4.1 20160919
Architecture: ARMv6-M
Core variant: Cortex-M0
Port Info:? ? Preemption through NMI
Platform:? ? STM32F072xB
Entry Level:? Medium Density devices
Board:? ? ? ? NanoVNA
Build time:? Aug? 2 2019 - 16:40:01

I have read about a lot of different versions of the NanoVNA and I'm afraid of bricking the unit and I need some advice for the latest firmware for this unit. A link where firmware could be downloaded would have been very nice!
I'm not very familiar with the different hardware versions, but I think the unit I have got is an "edy555 -design" based unit, is this correct?

The reason for upgrading firmware is the need of the screendump function, as I'm making a small utility for capture the screen to a PC program.

It would have been very nice to get some help with this update challenge!

Best regards Karl Jan - LA3FY

I have got a 2.8" NanoVNA, but I'm not sure what version and which firmware to use. Some help regardin unit identification and firmware version would be very appreciated! Thanks in advance!
Here is the unit:
It's a black sandwich type with the text in white. On the back there are symbols for the scrollwheel, a curve, on/off battery and USB symbol. The bottom line: "NanoVNA Very Tiny Handheld Vector Network Analyzer" uan at the right, the usuak "TX, REFL TRANS RX" and arrwos.
On the PCB I can see "NanoVNA H v3.2"
The splash-screen at startup shows: "gen111.taobao.com".
If sending a console command ("info") I get the following information:
Kernel: 4.0.0
Compiler: GCC 5.4.1 20160919
Architecture: ARMv6-M
Core variant: Cortex-M0
Port Info: Preemption through NMI
Platform: STM32F072xB
Entry Level: Medium Density devices
Board: NanoVNA
Build time: Aug 2 2019 - 16:40:01

I have read about a lot of different versions of the NanoVNA and I'm afraid of bricking the unit and I need some advice for the latest firmware for this unit. A link where firmware could be downloaded would have been very nice!
I'm not very familiar with the different hardware versions, but I think the unit I have got is an "edy555 -design" based unit, is this correct?

The reason for upgrading firmware is the need of the screendump function, as I'm making a small utility for capture the screen to a PC program.

It would have been very nice to get some help with this update challenge!

Best regards Karl Jan - LA3FY

Congratulations Andrea for beginning to get you head wrapped around some of these ideas!

Lets take baby steps on this bandwidth concept. Sure others can add their spin to this.

Bandwidth is a term which addresses the frequency response of a circuit.

If your circuit consisted of just resistors, for example a voltage divider, shown below, circuit 1,
the frequency response in not very interesting. It is flat. That is to say the relation
between the output voltage and the input voltage is constant. For equal R's, this
constant would be 1/2.

Now to make this a bit more interesting, we need to replace one of these resistors with an energy
storage element. Either an inductor or a capacitor will do. Depending on its location and the type
of energy storage element, we can realize a low pass or a high pass frequency response. Lets look at circuit 2.

You will note that while input voltage is constant 1 V, the output is also 1 V,
until the AC frequency is 1 kHz. The response is LOW PASS, and an interesting
point that we observe is that the output voltage is at 0.707 V at 1 kHz. This frequency point,
where the voltage across the capacitor is split equally split with that across the resistor is defined
as the BANDWIDTH of this RC circuit. Recall, the voltages across the R and C VECTOR
ADD as the phase shift between V and I in this little series circuit is 45 degress at 1 kHz. We see NO such
phase shift in circuit 1.

Key point of all this.... In order to address the idea of BANDWIDTH we must introduce
an energy storage element.

How are we at this point?

On Wed, Oct 21, 2020 at 01:44 AM, alan victor wrote:

PLEASE READ CHAPTER 3... AFTER THAT READ IF YOU HAVE ADDITIONAL QUESTIONS,
FEEL FREE TO ASK.

To be honest, I have to say I didn't read yet the whole chapter thoroughly, but this does not mean I don't feel like doing it, I simply need time. So far I did a hard work, anyway.
One of the reasons I'm already back here is to tell I'm quite confused about the concept of "bandwidth". The first two networks showed in that chapter are made of a capacitor and an inductor in series, and of a capacitor and an inductor in parallel. Here is far too easy to grasp the concept of "bandwidth", since the frequency response of such circuits is kind of a bell-shaped curve.
With my great surprise later I discovered L networks I already met a long time ago originate from a parallel of a capacitor and an inductor when the capacitor or the inductor sees a load at one of its sides, in other words when it does not go to ground directly but instead is connected to a load. What I know about these L networks is they behave as low-pass or high-pass filters, depending on the positions of the capacitor and the inductor. This means their frequency response may be roughly seen as the combination of an oblique ramp and of a flat horizontal line, though, of course, with no sharp angle involved. As far as I know just one "-3 dB" point is involved. So the only idea of "bandwidth" that comes to my mind is, possibly, how close is that point to the "flat response" region. At the same time, I wonder where in such a frequency response curve the "resonance frequency" would be: perhaps it has to be considered as the highest frequency - for low-pass filters - or the lowest frequency - for high-pass filters - with no attenuation, or, in other words, as the first or the last frequency within the supposed flat region? I attach a scrap of the text where I got confused: I can't see what else can be controlled, if not just how steep is the rise or the fall of the curve. In general, I don't know how to relate two aspects of the same circuit: the impedance adaptation that occurs at least at the resonance frequency and the high-pass or low-pass behavior that seems to involve an entire range of frequencies. Perhaps I can't explain how can a response of a filter be flat where there's no impedance matching between input and output.
Again, I'm damn confused. :-(

PAGE 47 SECTION 3-5 IS SO FUNDAMENTAL TO IMPEDANCE MATCHING OR IMPEDANCE
TRANSFORMATION, THAT I SUGGEST YOU READ IT OVER AND OVER UNTIL YOU CAN DO IT
IN YOUR HEAD WITHOUT PAPER AND PENCIL... SORT OF LIKE OHMS LAW.

I already isolated the pages related to the tables you're probably referring to (transformation from parallel connection to an equivalent series connection) in a sub-document.
I have to say, anyway, I'm still a bit concerned: in chapter 3 I could see so far just filters made of inductors and capacitors, but what puzzled my mind at the beginning was something made of nearly just resistors. Please look at the scrap I attach again for your convenience. Am I going to understand those particular combinations of components as well sooner or later? ;-)

Thanks!


A.