开云体育

great!
I know, here is not a correctly place to share it, but, do you have idea
how to save in my PC snp (s2p) file from a PNA ?
Thanks for.


Em ter., 10 de nov. de 2020 às 19:49, Jim Lux <jimlux@...>
escreveu:

Hello Nano VNA folks
Again, thank you for the feedback. Yes, this is what I asked for.

I try to be careful with language, but the slide on antenna "efficiency" was just sloppy.

My main point of putting this together was to look at how to interpret the various graphs that a VNA shows.
I am not an Electrical Engineer, and had no prior experience with the VNA vocabulary.
Six months ago I had no idea what a '"return loss" was, let alone explain why it is positive or negative.

Hams talk about SWR all the time. On nets, I often hear folks say they are worried since their SWR is 1.8:1 at some frequency, and they WANT 1:1.

The book by Walt Maxwell W2DU was fantastic reading for me and taught me a lot about SWR and feedlines and impedance.

I wanted to start my presentation with some basic antenna characteristics, like resistance, reactance, impedance and phase. Then branch into the VNA world to discuss how these parameters can be measured at least with reasonable accurately at HF with a $50 gadget and free software.

So that was my goal. I am adding some slides on "reflection coefficient" (rho) in tems of what various values of rho look like on a Smith Chart. Rho of zero is just one point on that graph: R = 50 ohms and zero reactance (with 50 ohm coax). So if you visualize the Smith Chart as a Dart Board, and the center is where you are aiming, then a SWR of 1:1 is only at the exact center of the dart board (Smith Chart).

So if ou miss the Bull's Eye, your reflection coefficient is bigger than 0. And how much you miss will indirectly tell you LOTS of information. The perimeter of the Smith Chart is a reflection coefficient of 1. Of course, that is just awful. Reflection Coefficient (0-1) leads to RETURN LOSS (dB) and that leads to SWR.
I think I now have an 8th grader understanding of all of these terms now.

What puzzled me was how to interpret the PHASE curves on simple one-band dipoles.
At resonance, reactance is zero (I get that) and PHASE crosses over from neg to pos.
WHY? If a ham (non engineer) can explain that in a few sentences, then that is a pretty good understanding of the concept of resonance. Of course, these are measurements made in my shack, about 100-150 ft of RG213 from the antenna being measured.

I find most hams (I talk with) think the SWR changes with feed line length (other than attenuation).
Many hams (I talk with) do not see why impedance changes with line length if Z is other than 50 ohms.
These can be easily confused by most of us in our (casual) discussions.
Running around 180 degrees in a Smith Chart was a real "eye-opener" for me, personally.

I noticed that QST article last May had a quick "review" of the Nano VNA but did not go into any detail explaining the relationships of the various graphs. Perhaps a second article for QST would help us non-engineer types see the value of a $50 VNA so we can adjust our antennas to work better.

Again, from a rookie at VNA language (but a ham for over 60 years)
Thank you. This IO group obviously has some very talented hams.

Barry k3eui

Hi Peter,

I had a working NanoVNA that I wanted to update, but it also didn't work with DfuSE due to only STM32 BOOTLOADER showing up in the Win10 device manager.
The STM32CubeProgrammer indeed did the trick (with only the usb connection!)

Steps I used with the Nano in programming mode (shortened pins):
- Connected the Nano to the pc via the usb cable, switched the device on, started STM32CubeProgrammer software.
- Switched the connection (Tab in the upper right corner) from ST-LINK to USB, and connected.
- In the 'Memory and File Edition' menu, I've set Size to 0x20000, Data Width to 8 Bits (Address of 0x0800000 showed already) like mentioned by QRP RX in this topic.
- Read the original data and saved it as backup (.bin format).
- Switched to the 'Erasing & Programming' menu, I ERASED the Flash Memory and wrote the firmware that QRP RX left in this topic.

Ended up with a working NanoVNA that has 4 traces now, and has a higher resolution! ('NanoVNA GEN111.TAOBAO.COM' showing on the splash screen when starting up).
(I did get it bricked when not erasing the flash memory before re-programming).

Thx for the solution QRP RX and Peter!
73 from happy ON7IVE

That was 19 words. :)

Joe,
You have a very old release of firmware. Read up on how to place your unit into dfu mode by shorting the boot 0 pins and then flash the latest firmware.You'll need to install the dfu utility or if using Linux the flashing is done with different commands.?
Please download and read one of the many user guides in the forum file section and watch some of the YouTube videos on flashing.?
Note: you can flash H FW on your unit but not H4 or F versions.?
Good luck.?


On Tue, 10 Nov 2020 at 2:23 PM, Joe (N1MID)<joeslushy@...> wrote: adding a command line "info" copy and paste

Hi Joe,

Welcome to nanoVNA users.
Indeed: he who dares wins. For someone who has a problem and doesn’t know the solution, it’s hard to articulate what their problem is.
The interviewer knows best what he is wondering about. Feel free to use the descriptions in the wiki and files folder.
If you’ve messed something up, you don’t have to panic because there’s some solution, you just don’t know about it.

Successful use for you

73, Gyula HA3HZ
--
*** If you are not part of the solution, then you are the problem. ( ) ***

Nothing ventured, nothing gained. I did a blind firmware update to get to 0.8.0 and now all is right with the nanoVNA. I have a config button. The risk was worth the reward and I appreciate those who've gone before me and produced the following guides:
Upgrade process:
Where to get firmware:
Shell commands (via Putty): /g/nanovna-users/files/NanoVNA_Console_Commands_Dec%209-19.pdf

adding a command line "info" copy and paste

On 11/10/20 9:58 AM, Antonio Carvalho wrote:

Jim, hello. How are you.
Do you have experience with SCPI commands and remote control to VNA
(general one)?
Cheers,

I've done some SCPI to a VNA - lots of SCPI to other instruments.
I know others at work who are doing lots of SCPI to fieldfox instruments: they want to get both "narrow band" high resolution data, and wideband data, so they command it to change the span, grab the data, then change the span, grab the data, etc.

Em qui., 29 de out. de 2020 às 18:52, Jim Lux <jimlux@...>
escreveu:

I wonder if there's a semi-standard set of SCPI commands for commercial
VNAs. Then one could make a SCPI : NanoVNA translation layer.

Why?
It might be useful to leverage other systems that have created
abstractions for network analyzers in general.

Hi all. Im new to my nanoVNA, but I've been browsing the Group. First thing to do is calibrate the touchscreen. I think I am missing some key functionality, the Config menu is missing. So, that brought me to think, perhaps the FW was corrupted. I've browsed around on the wiki and topics and could not find anyone with a similar problem. I went looking for what firmware I was on and discovered that its under the missing config menu.
Ok, perhaps NanoVNASaver has the firmware, right? Download, plug in, scan ports, connect and I see data points flowing in, Great. I picked the About button in Saver and the FW is v0.0.0. That's probably wrong. The CMD line for nanoVNASaver is attached.
So, what is a newbie to do? All thoughts are welcome.

On Tue, 10 Nov 2020 at 14:57, Barry Feierman <k3euibarry@...> wrote:

Thank you for the suggestions.

My casual use of "efficiency" of an antenna did not add anything to the
slide show.

That's personally where I see a problem - the *casual* use of a technical
term. In my opinion, it would be more accurate to remove the word
"efficiency" and replace it with something that gets your point over,
without using that word.

Another word that is abused is directivity. People have some vague idea
what they mean by that, but use it incorrectly. I recall an article in
RadCom where the author suggested the reader check the directivity of the
antenna by rotating it 180 degrees, and looking at the S-meter. Apart from
the fact that S-meters vary wildly in their readings, this is a poor way to
measure the front to back ratio, not the directivity.

Barry k3eui

Dave G8WRB

Jim, hello. How are you.
Do you have experience with SCPI commands and remote control to VNA
(general one)?
Cheers,



Em qui., 29 de out. de 2020 às 18:52, Jim Lux <jimlux@...>
escreveu:

On Tue, Nov 10, 2020 at 04:37 PM, Shane Youhouse wrote:

It has been implied that Steve "borrowed" some of his information from another
source.

Exchanging emails with Steve at the time, I'm aware that there was a lot of interchange of information regarding the subject between various key amateurs.

This K9YC presentation is probably the most relevant to this particular discussion.



---
Regards,

Martin - G8JNJ

It has been implied that Steve "borrowed" some of his information from another source.

You may want to check out and go to the bottom of the page. There you will find more than you'll know what to do with in regards to chokes.

--Shane
KD6VXI

On Tue, Nov 10, 2020 at 03:40 PM, AG6CX wrote:

Martin, I’d love to see your sketches or diagrams that more accurately
depict the glow of CMC. No challenge, just curiosity.

Thermographs attached.

The first shows a 4:1 Unun wound on a low permeability core the second shows a 4:1 Unun wound on a high permeability core.

Taken from this document, which I wrote when I first started investigating baluns and ununs.



Ideally it needs updating, as I have learnt a lot more in the intervening period, and some of the content requires further clarification or correction, but I can't find my original text to be able to do this easily. However the basic information is valid, and I think the graphs and illustrations are instructive.

--
Regards,

Martin - G8JNJ

Dave, Martin, et al:

What I belief to be a seminal summary of the matter.



Now to find a six-inch diameter Ferrite toroid of acceptable material to run that open line through!!

Ed McCann
AG6CX

Dave, Martin et all:

Re measurement of CMC on either coax OR ladder line, you may want to consider the following as context:



I have built and used the evolved design with what I thought was success.

Admittedly, there is a challenge finding a toroid large enough to handle true open wire 600 ohm line.

I will forward another reference that you may have missed by Owen Duffy.

Martin, I’d love to see your sketches or diagrams that more accurately depict the glow of CMC. No challenge, just curiosity.

Keep up the good work.

Ed McCann
AG6CX

Thank you for the suggestions.

My casual use of "efficiency" of an antenna did not add anything to the slide show.

I mainly wanted to show the relationships of
Reflection coefficient, return loss, SWR, impedance, R and X, and phase
But without getting too deep into the weeds and the math of complex numbers.

When a dipole is operating at its resonant frequency, the current and the voltage at the feed poin are in phase.
WHY?
Most hams I have talked with cannot tell me WHY that is so.
And why does operating below resonance get you into capacitive reactance?
Why does operating above resonance get you into inductive reactance?
Why at a resonant frequency do these two cancel?

And, what can you tell by just looking at a Smith Chart graph of an antenna?
That was what I wanted to concentrate on.

And I admit, I am a rookie at this stuff, but learning fast.

Agn, TU for suggestions

Barry k3eui

On Tue, 10 Nov 2020 at 12:07, Richard Hankins <g7rvi@...>
wrote:

On 09/11/2020 20:51, Dr. David Kirkby, Kirkby Microwave Ltd wrote:

2) You talk about efficiency of an antenna, but don't define it. Most
people don't have a clue what efficiency is. The generally accepted
definition amoung professionals comes from IEEE standard 145. Efficiency

is

the power radiated divided by the power absorbed by the antenna. Note the
word absorbed - it has nothing to do with the incident power. So if you
have a crap SWR, you transmit 100 W, 99 W gets reflected, and 0.95 W gets
radiated, then the antenna is 95% efficient, despite you would probably

not

consider it a very good antenna.

David,

surely the antenna in your example is fine - it radiates the power it
actually receives. What's crap is the matching ! Hardly the fault of
the antenna.....

Richard
G7RVI

Richar,
my point is, that on a document aimed at hams, on fundamentals, to use
efficiency, without defining it, is not a good idea. If this was an IEEE
Antennas and Propogation journal, it would be different.

As Jim Lux said, in response to my post

*"I agree - Efficiency is a tricky word when associated with antennas. I
try to stay away from it, ..."*

If the antenna impedance is 0.5 ohm, then it would have the 100:1 VSWR I
mention when measured in a 50 ohm system. That would be tricky to match to.
Efficient yes, but not easy to use.

I personally feel, that on something aimed at amateurs, to use the word
"efficiency" is not a great idea, unless one is going to describe in detail
about what efficiency is. It's one of those words, that 99% of hams will
not know the true meaning, but will all think they have a fairly good idea
of what it meant by an efficient antenna.

The original poster asked for feedback, so that is my thought on the
matter.

Dave

On 09/11/2020 20:51, Dr. David Kirkby, Kirkby Microwave Ltd wrote:

2) You talk about efficiency of an antenna, but don't define it. Most
people don't have a clue what efficiency is. The generally accepted
definition amoung professionals comes from IEEE standard 145. Efficiency is
the power radiated divided by the power absorbed by the antenna. Note the
word absorbed - it has nothing to do with the incident power. So if you
have a crap SWR, you transmit 100 W, 99 W gets reflected, and 0.95 W gets
radiated, then the antenna is 95% efficient, despite you would probably not
consider it a very good antenna.

David,

surely the antenna in your example is fine - it radiates the power it actually receives.?? What's crap is the matching ! Hardly the fault of the antenna.....


Richard

G7RVI