开云体育

Maybe also put
"Press control or touch screen for menu"
into a horizontal box, and on 1 line instead of 3, similar to the "Display" box, and have the left side of it even with, and above, the "Display" box.
That would make it just a little bit narrower also.

Thank you for the nanoVNA menu diagram! It's helped me more than once.

Hi Sean,

Your VNA will be used to measure your antenna or other elements in shunt form or it could be used to measure in series through form, that would be a S21 measurement. However, for sake of simplicity let's confine ourselves to SERIES form. That case provides you with S11. And S11 when properly handled will result in the SERIES impedance. You can than convert that series Z to its equivalent parallel form. The method for doing this is quite well documented. Just look for "converting series impedance to its parallel form". Currently, the nano save PC program does that conversion. However, its worthwhile understanding the arithmetic behind the scenes. Its not hard.

Once you have the series form of the Z for the antenna which may be complex, you will have to conjugate match that to your other device. There are a number of utilities that preform that task. Again, the math behind this process is not hard. A portion of the Z, the real part contains both the radiation R as well as the portion that is LOSS. That ratio between radiation R and loss R is sometimes referenced as the antenna efficiency factor.

If you have issues with any of this I highly recommend you get a copy of the TEXT Solid State Radio Engineering by Krauss, Bostain, Raab and READ CHAPTER THREE. The discussion there is EXCELLENT. Hell... Read the whole BOOK!.

Regards, Alan

I had the .dfu file generated and uploaded.
The edy555 firmware didn't convince me ... then I discovered that I have a problem with all types of firmware (NanoVNA-edy555, NanoVNA-H):
If you execute and save more than two calibrations, the others saved make me show always SWR 1:1, even with the SMA connector open (CH0)!

Usually memories (calibrated) that I saved are this:
0) 1Mhz-900Mhz; track 1: SWR CH0; track 2: Smith CH0
1) 1Mhz-30Mhz; track 1: SWR CH0; track 2: Smith CH0
2) 30Mhz-100Mhz; track 1: SWR CH0; track 2: Smith CH0
3) 80Mhz-500Mhz; track 1: SWR CH0; track 2: Smith CH0
4) 1Mhz-900Mhz; track 1: LOG CH0; track 2: LOG CH1 (for filter)

Note: before any upgrade I used the file for cleaning "DMR-CLEAR_MEMORY_DFU.dfu " (131 kB; Sep 30).

Now I am forced to save only 2 memories:
0) 1Mhz-900Mhz; track 1: SWR CH0; track 2: Smith CH0
1) "empty"
2) "empty"
3) "empty"
4) 1Mhz-900Mhz; track 1: LOG CH0; track 2: LOG CH1 (for filter)

Why?

Thanks

Hi Herb,
I would actually suggest holding back for just a few days; NanoVNA-Saver
0.1.0 doesn't work that well with 0.2.2. The problems should be fixed in my
next release.

:-)

--
Rune / 5Q5R

I have been a long-time user of Matlab; however, the license (number 12652) I use professionally cannot be used by me in a private setting.

I recently learned of GNU Octave at . This is free software which will run many Matlab scripts. However, I don't think it will not run everything directly. They have many "packages" which are similar to Matlab toolboxes, I think. All of it is free to download and use. It might be worth checking out the capabilities of this software. I do know that they have some serial interface capability which enables communicating with devices like the nanoVNA.

73,
--
Bryan, WA5VAH

Rune,
Thanks for the heads up. I've been hesitant to upgrade to the 0.2.2 firmware because I haven't had a compelling reason to do so. I think you just gave me one :)

Herb

The only discrepancy - which is fatal to the software working - that I have
seen thus far, is that the developers have changed the prompt line, which I
use to detect when output from the device has finished. Being able to
detect either prompt might make it work, or there might be other
differences. I don't have a way to test this at this time.

edy555's firmware has recently received a number of updates the use of
which is limited to newer firmwares, but which are pretty much required to
have both fast and stable PC control of the NanoVNA. I'm looking at
implementing support for these in the next version, or the one after, of
NanoVNA-Saver.

I'm all in favour of trying to support the variety of devices and firmwares
that are appearing, but the software is primarily going to be tested
against the hardware I have - a NanoVNA-H running edy555's 0.2.2 firmware
at the moment.

--
Rune / 5Q5R

Paul,
Feedback from users so far is that the command set for the NanoVNA-F is not fully compatible with the NanoVNA and, therefore neither NanoVNA-saver or NanoVNASharp work with it.

If the only problem was adding the NanoVNA-F's VID and PID to the getPort() function of NanoVNA-saver, Rune would have made those accommodations happily. My opinion is the NanoVNA-F's developers are going to modify the firmware so that it's command set overlaps the NanoVNA. The second option is that the NanoVNA-F's developer's will branch a version of NanoVNA-saver specifically for the NanoVNA-F. Doing so would mean any improvements Rune made to NanoVNA-saver would not be immediately available to NanoVNA-F users.


Herb

IMO, you are probably better off measuring the series impedance and converting it to a parallel impedance because of the inaccuracy of the NanoVNA when measuring very high impedances.

Hi, aa_talaat,

Here is a suggestion.

I would recommend that you connect the inductor from the center conductor of port 0 to the ground of port 0 with the shortest possible wires. If you could, I would recommend soldering it across an SMA female connector that directly connects to the location where you did the Open, Short, and Load calibration for S11. In your most recent pictures, with short cables, that would mean you use an SMA femaile connector and solder the part to the back of the SMA connector where you would normally mount it to the circuit board. As long as you connect to the same point as you did the open, short, and load calibration, the measurements should be pretty good. You can then measure the inductor directly by observing the S11 information.

Several of the programs (nanoVNASaver or nanoVNA_mod_v2 for example) will show you the equivalent parallel impedance of the device connected to port 0. What you should see on the Smith chart is a short at very low frequencies, say 50 kHz, (a dot near the left side of the Smith Chart) with an increasing impedance (primarily inductive reactance) of the device you have connected. On the Smith chart the plot should start near the left edge of the horizontal axis and proceed clockwise around the outer circle on the Smith chart as the frequency is increased. Based on what you have said, I wouldn't go much beyond 30-100 MHz as the stop frequency; however, experimenting with the stop frequency would be instructive regarding the device you are measuring. At some frequency, the inductor will appear as a very high impedance (this will be reflected by the plot going to the right side of the chart) because it will have a parallel resonance which is an indication of the amount of capacitance in your coil.

I hope this helps.

--
Bryan, WA5VAH

I have 2 old but new metal pens with a nylon tip. Previously used to transfer rubbing letters and stripes to a copper print for etching. Works great !

Like this?

Narrow gif with white background:

how do we correct an S21 measurement?

Has anyone looked at S21 for a mixer as DUT,
where other mixer input is e.g. sinusoid or sawtooth?

37 : ann : the uncertainties of our nanovna will be estimated tomorrow

For the record, Nanovna-saver looks for Nanovna USB id's

For the Nanovna-F I get:
usb 3-11: new full-speed USB device number 20 using xhci_hcd
[13509.779971] usb 3-11: New USB device found, idVendor=0483,
idProduct=5740, bcdDevice= 2.00
[13509.779976] usb 3-11: New USB device strings: Mfr=1, Product=2,
SerialNumber=3
[13509.779978] usb 3-11: Product: NanoVnaPro Virtual ComPort
[13509.779980] usb 3-11: Manufacturer: SYSJOINT
[13509.779982] usb 3-11: SerialNumber: 00000000001A
[13509.783606] cdc_acm 3-11:1.0: ttyACM1: USB ACM device

thanks, the smith chart tutorial was nice, the matching network I'm dealing with is a bit more involved as it consists of an emc low pass filter on the rfid chip amp, then the matching L network going to the coil antenna, there are some useful tools provided by the chip manufacturer to design the matching circuitry but the parameter I'm missing is the parallel R at resonance, I don't think it's equivalent to the DC resistance of the coil... so that's where I'm a bit stuck trying to figure out a way to measure it.

Sweet!
Nice work.?



On Sun, 6 Oct 2019 at 3:06 PM, Oristo<ormpoa@...> wrote: > If you'd like to make this diagram slightly narrower,

the right-most rows on calibrate and format could be made to go vertically down.

Like this??

The S Parameters are defined in terms of a circuit within a closed box. Snm is the amplitude of the signal coming out of port n relative to the signal that went into port m. Thus, S21 is the signal that comes out of port 2 relative to what went into port 1. For a two port network that is the transmitted signal. S11 is what comes out of Port 1 relative to what goes into Port 1, so it is the reflected signal. All ports are assumed to be terminated in a matched impedance for whatever you use as the calibration impedance. This means there are no reflections off the generator or the external loads.

Some textbooks explain this more clearly than others.

One important thing to note is that for passive networks, i.e. no amplifiers or other sources, S21=S12.

I do a lot of analysis of N port networks for coupled cavity systems. These are to understand the properties of rf linear accelerators, which are nothing more than a type of bandpass filter. I find the chain matrix notation more useful than S Parameters. The chain matrix, sometimes called the ABCD matrix, relates the voltages and currents at one set of terminals, the input, to the voltages and currents at another set of terminals. For a two port network with voltage V1 and current I1 a the input and V2 and I2 at the output this gives the circuit equations V2=A*V1+B*I1 and I2=C*V1+D*I1. Note that the conventional definition of the current is that I1 is into the network and I2 is out of the network.

Given the voltage and current at a terminal the incoming wave amplitude a and outgoing wave amplitude b can be defined as a=0.5*(V/sqrt(Z0)+I*sqrt(Z0)), and b=0.5*(V/sqrt(Z0)-I*sqrt(Z0)). The scaling isn't important since the S Parameters are ratios of outgoing waves to incoming waves, but you can set it so the sum of all a^2 equals the total power input.

There is another way to look at networks called the impedance matrix which relates all terminal voltages to all terminal currents. This is what you usually get by applying Kirchoff's law to a circuit.

The point of the above is that you can use ordinary circuit analysis to a network and calculate the S Parameters to develop an understanding of how they relate to the parameters of an ordinary circuit, such as an inductor, capacitor, resistor or resonator.

This can involve a lot of messy algebra, which can easily get screwed up by mistakes. I find Mathematica to be a powerful tool, although sometimes it takes some effort to get an algebraic result in a "neat" form.

The NanoVNA is a pretty amazing instrument for its price. I think it is good not to confuse it with a laboratory instrument, but it is a great learning tool. It also has an immediate application that is useful to Radio Amateurs, understanding antennas and filters.

I have enjoyed following the discussions in this forum.

73 de K9GXC, Jim

If you'd like to make this diagram slightly narrower,
the right-most rows on calibrate and format could be made to go vertically down.

Like this?

If you'd like to make this diagram slightly narrower, the right-most rows on calibrate and format could be made to go vertically down.



On Sun, 6 Oct 2019 at 2:48 PM, Oristo<ormpoa@...> wrote: Oops, previous menu gif background was light gray;
whitened: