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Something that I have never fully understood is that S21 is supposed to be measured using a "matched load". Isn't the "matched load" of a VNA equal to 50 ohms? Are we to assume that 50 ohms is the only possible "matched load"? Or can a VNA be calibrated for any value of "matched load"?

Also, LTspice from Linear Technology (now part of Analog Devices) has been freely avaiable for a long time. There is a Yahoo group, LTspice, which provides excellent support and information.

DaveD

Sent from a small flat thingy

Sean,Are you aware that the simulation software call MicroCap is now free?

Try simulation first to give you a rough idea of your component values, then prototype and test.?
Regards
Larry

On Sun, 6 Oct 2019 at 12:34 PM, sean@...<sean@...> wrote: I am aware of that, like I said, I'm new to RF, but I understand that without a non reactive part of impedance in the antenna, there's no power going into the antenna right?? If the LC is at resonance, the impedance is infinite, therefore, there can be no watts.? I am assuming the parallel R at resonance partly consists of the power radiated into space, and partly other effects of the current flowing through the LC tank.? In the case of RFID, because the passive receiver is powered by the RF field, part of the power sent to the antenna is dissipated in the receiver circuitry through coupling.? What I'm trying to figure out is: am I chasing the right thing when it comes to designing a matching network?? and is the nanoVNA capable of measuring the real component of impedance at the resonant frequency with any accuracy.

On Sun, 6 Oct 2019 at 12:34, <sean@...> wrote:

What I'm trying to figure out is: am I chasing the right thing when it comes to designing a matching network?

With respect to matching networks, have you seen W2AEW's Youtube
channel?
Also, do follow the link to W0QE's Youtube channel: SimSmith is very
nice software.

--buck

Very nice, thanks.?



On Sun, 6 Oct 2019 at 11:45 AM, Oristo<ormpoa@...> wrote: > > I hope there will be no objection to me sharing

HTML is in public domain

Easier to print:

Yes, I meant correction.You have a save menu after the correction button.. shouldn't be one. Correction is on or off.I still think reset should be at the top of the list and save after calibrate steps.?


On Sun, 6 Oct 2019 at 11:33 AM, Oristo<ormpoa@...> wrote: Hi Larry -

When you click the DFU menu button, you get the next menu with 2 items:
Reset and Enter DFU and Cancel.

OK, I never dared press DFU
and anyway added a slide switch for hard DFU,
too often required for hangs..

The full word:. Calibration is a switch that can be inverted text
to show calibration is being applied,
or normal text to show calibration is not being applied.?

OK, I see "CORRECTION", not "Calibration"

How often do you turn it on or off?

Maybe raw data helps understanding impact of shielding and layout changes?

I am aware of that, like I said, I'm new to RF, but I understand that without a non reactive part of impedance in the antenna, there's no power going into the antenna right? If the LC is at resonance, the impedance is infinite, therefore, there can be no watts. I am assuming the parallel R at resonance partly consists of the power radiated into space, and partly other effects of the current flowing through the LC tank. In the case of RFID, because the passive receiver is powered by the RF field, part of the power sent to the antenna is dissipated in the receiver circuitry through coupling. What I'm trying to figure out is: am I chasing the right thing when it comes to designing a matching network? and is the nanoVNA capable of measuring the real component of impedance at the resonant frequency with any accuracy.

Hi aa--something
Cables length as such has basicly no influence. Consider the cable as part of the hardware system, they are calibrated away.
The only effect is small potential phase variation if the cable are bended between calibration and connecting to a DUT.
Some cable are more phase stable than others
Kind regards
Kurt

-----Oprindelig meddelelse-----
Fra: [email protected] <[email protected]> P? vegne af aa_talaat via Groups.Io
Sendt: 6. oktober 2019 15:01
Til: [email protected]
Emne: Re: [nanovna-users] Inductor S21 measurement using nanoVNA

Hi,
I replaced the cables with much shorter ones, and re-calibrated using these 2 new cables (see attached photos), and I am getting the same results. Not sure the cables interfere with the nanoVNA results. As far as I remember, cables longer than wave length/8, I should worry about transmission line effects. However, in this case, the cables are 10 cm long each, and the subject frequency is 60MHz.

Thank you Erik, that explains it, an image.? So I just ignore the lower frequency of the two peaks.? And it's possible to calibrate the amplitude.? I will try the test of seeing the FM BC band with an antenna.
Bob

See /g/nanovna-users/topic/34079496#3464

I tried my nanovna as a spectrum analyzer and it is interesting.? Amplitude isn't calibrated.? I measured my signal generator and it shows me two responses fairly close together; I verified on my 'real' SA that there is only one signal.? But it could be handy in some cases.? It showed me sidebands of the signal with AM and FM, for instance.? I kept the input signal down around -25 dBm.
Bob

Hi Larry -

When you click the DFU menu button, you get the next menu with 2 items:
Reset and Enter DFU and Cancel.

OK, I never dared press DFU
and anyway added a slide switch for hard DFU,
too often required for hangs..

The full word:. Calibration is a switch that can be inverted text
to show calibration is being applied,
or normal text to show calibration is not being applied.?

OK, I see "CORRECTION", not "Calibration"

How often do you turn it on or off?

Maybe raw data helps understanding impact of shielding and layout changes?

I hope there will be no objection to me sharing

HTML is in public domain

I wanted a printed chart that I can hang on my wall so I changed the color scheme. I hope there will be no objection to me sharing an ink-saving chart.

gin & pez @ arg;

I am comforted that I seem to be approaching a conceptual understanding of your work. It has elevated my interest.

I am responding to your question with an expanded definition that is intended to enable the separation of the hardware and software components of “Any” VNA measurement.

More precisely, any VNA measures amplitude vs. frequency, and either measures or computes phase in accordance with the architecture of its design, and then performs the mathematics required to yield a result that is declared the complex relationship between a power generated by a source and the power either passed, attenuated/absorbed, or amplified (S21, S12,... Smn, Snm) through a device under test (DUT) or load, and/or the complex relationship between a power generated by a source and the reflected/rejected power at the injection port of the device under test (DUT) or load (S11, S22,... Snn ).

These complex relationships, called Scattering parameters and expressed as transmission and reflection coefficients respectively, are then compared to a normalized set of measurements made of a set of reference impedance standards; the result of which is then used to compute the parameters of influence to transmission, and absorption or reflection by a device under test (DUT).

In the context and spirit of your question as I believe it to be, your statement defines the “hardware” requirements of any VNA measurement system, and we are in agreement on this point. To that end, the primary task of Any VNA is to output a frequency associated complex number pair that is representative of the transmission or reflection coefficient or coefficients it has been configured to provide. Beyond that task, and whether performed internally or externally, all else is derived computationally.

My apologies for not providing the terse response solicited.

--
73

Gary, N3GO

When you click the DFU menu button, you get the next menu with 2 items: Reset and Enter DFU and Cancel.?
The full word:. Calibration is a switch that can be inverted text to show calibration is being applied, or normal text to show calibration is not being applied.? How often do you turn it on or off???



On Sun, 6 Oct 2019 at 10:12 AM, Oristo<ormpoa@...> wrote: Hi Larry -

I think on the CAL line, reset should be the very first item opposite CAL and
everything else is below. Why? You need to do a reset before you do the rest
of the cal steps.

I totally agree and can rearrange that on the tree..

Leave 'calibration' at the bottom as you rarely use it.

Actually, I calibrate pretty often, nearly every time before
measurement, to consider everything except DUT as "ideal".

Also, as soon as you press Done, you get the save menus, no?

Yes, but my CSS is not good enough for two branches to SAVE
.. but I can duplicate SAVEs!

There is one more entry after the DFU button

I see only BACK and do not bother mapping those.

Thanks for the feedback!

On Sun, Oct 6, 2019 at 05:13 AM, <sean@...> wrote: > ... but the parallel resistance at resonance is effectively the radiated power of the antenna, yes?

Since ohms are obviously not watts, please give us the formula that you are using for that conclusion.

Hi Larry -

I think on the CAL line, reset should be the very first item opposite CAL and
everything else is below. Why? You need to do a reset before you do the rest
of the cal steps.

I totally agree and can rearrange that on the tree..

Leave 'calibration' at the bottom as you rarely use it.

Actually, I calibrate pretty often, nearly every time before
measurement, to consider everything except DUT as "ideal".

Also, as soon as you press Done, you get the save menus, no?

Yes, but my CSS is not good enough for two branches to SAVE
.. but I can duplicate SAVEs!

There is one more entry after the DFU button

I see only BACK and do not bother mapping those.

Thanks for the feedback!

edy255's 0.2.2 ch.hex sadly has tiny font..

Also, touch screen seems much less responsive than Gen Hu releases,
and hung repeatedly (requiring power off/on) when trying to set START stimulus..

... back to NanoVNA-H__900_ch_20191003.dfu