1.2.40 strange displayed S11 Smith value
Hi all
something doesn't seem to be working very well, the most recent firmware 1.2.40 of DiSlord installed on SEESII H4, I really appreciated the characteristic impedance conversion function for SWR measurements and for the Smith graph, but the impedance values ??of port2 should not change in fact they are what they are.
but by measuring the input of port2 with the S11 Smith function it gives 77.7 Ohm as long as the conversion value 50-->77.7 Ohm is configured while it is supposed to give 50 Ohm, then by putting a 50 Ohm load on S11 Smith it displays the value 50 Ohm,
So the Port2 impedance seems has really changed impedance when we put 50 Ohm --> 77.7 Ohm if not how can we explain this displayed value which does not match our 50 Ohm prediction ?
73's Nizar
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Southeastern VHF Conference?2025 Announcement &?Call For Papers
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Re: Measuring R,X Resonant Frequency
?
If you draw a band between 51,5 and 48,5 ohms over the graphic you will see that the sensibility of minimum SWR point is very high , then with coaxial impedance variations this frequency would be even higher than resonant frequency. For this reason there are no practical reasons to go deeper in this analysis.
Regards, Patricio.
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Show quoted text
On 21 Jan 2025, at 3:20?PM, W0LEV via groups.io <davearea51a@...> wrote:
Maximum power transfer occurs with a zero-ohm source.
Further, the impedance of the vast majority of good 50-ohm coaxial cable is
typically ± 3 %. Here is a quote for Amphenol RG-58U (from the Amphenol
www page for RG58):
[image: image.png]
So the typical impedance of this cable can vary between 51.5 and 48.5
ohms. That's not much and pretty insignificant when considering an "energy
pipe" between an ill-defined impedance of a loop vs. frequency and a
well-defined impedance vs. frequency of an amplifier. So, eliminate the
argument that the coax impedance is variable and impacts ultimate
performance of the loop(s).
Dave - W?LEV
On Tue, Jan 21, 2025 at 5:25?PM Patricio A. Greco via groups.io <>
<patricio_greco@... <mailto:patricio_greco@...>> wrote:
This is the typical case if mixing concepts.Its very crear that the
amplifiers don?t have a 50 ohm resistor inside , un less you live in a very
cold place and need some extra heating… My idea were to show that has no
sense to worry about resonance and minimum SWR in this case and also
consider the source impedance that differs of Z2 on VNA. The minimum SWR
that shows the VNA is a calculation using the calibration standards , If
you really would like to know the SWR over the transmission line there are
other methods because the coaxial cables has not exactly 50 Ohms and if we
condider the system as unidirectional the only purpose is to transfer the
maximum power to antenna the minimum SWR must to be measured over the
transmission line. In the other hand the output impedance of an amplifier
don’t only define his efficiency, this is other concept mixing.
Ing. Patricio A. Greco
Taller Aeronáutico de Reparación 1B-349
Laboratorio de Calibración ISO 17025 AREA: RF/MW
Gral. Martín Rodríguez 2159
San Miguel (1663)
Buenos Aires
T: +5411-4455-2557
F: +5411-4032-0072
www.servicios-electronicos.com.ar
On 21 Jan 2025, at 13:24, Fran?ois via groups.io <18471= [email protected]> wrote:
You are right to ask yourself. There is one fundamental thing that you
forget, that the TX -> line -> Antenna system is only adapted in one
direction.
The antenna adaptation devices (box for example) only serve to bring 50
ohms to the TX terminals. Fortunately, the Tx does not have 50 ohms of
internal impedance but only one or two ohms, otherwise the efficiency would
be catastrophic.
If when looking back at your antenna you see 50 ohms, your antenna
looking towards the TX does not see 50 ohms.
On the other hand, once your agreement is complete with your coupling
box, if you turn the coupling box over, that is to say place 50 ohms in
place of the TX and look, with a NanoVNA, through the antenna base, you
will see the same impedance as that of your antenna. This is a way to
preset a remote adapter.
Keep in mind that if the generator impedance is fixed you will get the
maximum power out of it in a combined load (50% efficiency). But if you are
left free to choose the internal impedance of the generator, whatever the
load, the maximum power will come out of the generator if its internal
impedance is zero (100% efficiency).
--
F1AMM
Fran?ois
--
*Dave - W?LEV*
--
Dave - W?LEV
<image.png>
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Re: Measuring R,X Resonant Frequency
As such, there is no R/X chart. Using the Smith Chart and the cursors, you can read the R ± jX at the top of the screen at the frequency of the cursor. The complex impedance can be expressed either as R ± j X in ohms or R (ohms) ± the actual reactance of the complex portion of the impedance at the cursor frequency in uH (+) or pF (-). The RigExperts and the NANOVNAs are ball parks apart from eachother. Dave - W?LEV On Tue, Jan 21, 2025 at 7:37?PM Roger Need via groups.io <sailtamarack= [email protected]> wrote: On Sun, Jan 19, 2025 at 11:14 AM, Peter Jones wrote:
SWR is fine, but I can't see anything online about an R/X chart (similar
to
that available on the RigExpert).
Can I do this on the NanoVNA V4?
On the NanoVNA-H4 you have to plot R and X using a separate trace for
each. However you can plot R and X on the same graph using RigExpert's
AntScope 2 program which does interface to a NanoVNA-H4. Or you can use
the NanoVNA Saver program. Here is an annotated plot from NanoVNA Saver of
a 2M dipole
Roger
-- *Dave - W?LEV* -- Dave - W?LEV
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Re: Measuring R,X Resonant Frequency
Thanks for taking the time to fully answer my question.
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Show quoted text
On Tue, Jan 21, 2025 at 07:37 PM, Roger Need wrote:
On Sun, Jan 19, 2025 at 11:14 AM, Peter Jones wrote:
SWR is fine, but I can't see anything online about an R/X chart (similar to
that available on the RigExpert).
Can I do this on the NanoVNA V4?
On the NanoVNA-H4 you have to plot R and X using a separate trace for each.
However you can plot R and X on the same graph using RigExpert's AntScope 2
program which does interface to a NanoVNA-H4. Or you can use the NanoVNA
Saver program. Here is an annotated plot from NanoVNA Saver of a 2M dipole
Roger
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Re: NanoVNA H4 microSD Card
Please read my previous post. I upgraded the firmware and found it. I was just suggesting that the getting started guide needs updating. If you read this it does not mention the SD card.
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Show quoted text
On Tue, Jan 21, 2025 at 07:47 PM, Clyde Lambert wrote:
You haven't look very hard. First, READ the WiKi on the groups files section.
Second look at past posts. This has been covered many times.
Third, there are several ebooks or hard copies available, for a modest price.
Check on Amazon. I have two very good ones from Amazon.
The NanoVNA H4 is very easy to use if you learn the menus.
KC7BJE
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Re: NanoVNA H4 microSD Card
You haven't look very hard. First, READ the WiKi on the groups files section.
Second look at past posts. This has been covered many times.
Third, there are several ebooks or hard copies available, for a modest price. Check on Amazon. I have two very good ones from Amazon.
The NanoVNA H4 is very easy to use if you learn the menus.
KC7BJE
|
Re: Measuring R,X Resonant Frequency
On Sun, Jan 19, 2025 at 11:14 AM, Peter Jones wrote:
SWR is fine, but I can't see anything online about an R/X chart (similar to
that available on the RigExpert).
Can I do this on the NanoVNA V4?
On the NanoVNA-H4 you have to plot R and X using a separate trace for each. However you can plot R and X on the same graph using RigExpert's AntScope 2 program which does interface to a NanoVNA-H4. Or you can use the NanoVNA Saver program. Here is an annotated plot from NanoVNA Saver of a 2M dipole Roger
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Re: Using the H4 as a Signal generator with
On Mon, Jan 20, 2025 at 08:40 PM, <sillysausage288@...> wrote:
is the h4 a sa or vna?.
VNA... The full name is NanoVNA-H4. Manufactured by Hugen and sold on the Zeenk AliExpress store or from various distributors like R&L in USA
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Re: Measuring R,X Resonant Frequency
Maximum power transfer occurs with a zero-ohm source. Further, the impedance of the vast majority of good 50-ohm coaxial cable is typically ± 3 %. Here is a quote for Amphenol RG-58U (from the Amphenol www page for RG58): [image: image.png] So the typical impedance of this cable can vary between 51.5 and 48.5 ohms. That's not much and pretty insignificant when considering an "energy pipe" between an ill-defined impedance of a loop vs. frequency and a well-defined impedance vs. frequency of an amplifier. So, eliminate the argument that the coax impedance is variable and impacts ultimate performance of the loop(s). Dave - W?LEV On Tue, Jan 21, 2025 at 5:25?PM Patricio A. Greco via groups.io <patricio_greco@...> wrote: This is the typical case if mixing concepts.Its very crear that the
amplifiers don?t have a 50 ohm resistor inside , un less you live in a very
cold place and need some extra heating… My idea were to show that has no
sense to worry about resonance and minimum SWR in this case and also
consider the source impedance that differs of Z2 on VNA. The minimum SWR
that shows the VNA is a calculation using the calibration standards , If
you really would like to know the SWR over the transmission line there are
other methods because the coaxial cables has not exactly 50 Ohms and if we
condider the system as unidirectional the only purpose is to transfer the
maximum power to antenna the minimum SWR must to be measured over the
transmission line. In the other hand the output impedance of an amplifier
don’t only define his efficiency, this is other concept mixing.
Ing. Patricio A. Greco
Taller Aeronáutico de Reparación 1B-349
Laboratorio de Calibración ISO 17025 AREA: RF/MW
Gral. Martín Rodríguez 2159
San Miguel (1663)
Buenos Aires
T: +5411-4455-2557
F: +5411-4032-0072
www.servicios-electronicos.com.ar
On 21 Jan 2025, at 13:24, Fran?ois via groups.io <18471= [email protected]> wrote:
You are right to ask yourself. There is one fundamental thing that you
forget, that the TX -> line -> Antenna system is only adapted in one
direction.
The antenna adaptation devices (box for example) only serve to bring 50
ohms to the TX terminals. Fortunately, the Tx does not have 50 ohms of
internal impedance but only one or two ohms, otherwise the efficiency would
be catastrophic.
If when looking back at your antenna you see 50 ohms, your antenna
looking towards the TX does not see 50 ohms.
On the other hand, once your agreement is complete with your coupling
box, if you turn the coupling box over, that is to say place 50 ohms in
place of the TX and look, with a NanoVNA, through the antenna base, you
will see the same impedance as that of your antenna. This is a way to
preset a remote adapter.
Keep in mind that if the generator impedance is fixed you will get the
maximum power out of it in a combined load (50% efficiency). But if you are
left free to choose the internal impedance of the generator, whatever the
load, the maximum power will come out of the generator if its internal
impedance is zero (100% efficiency).
--
F1AMM
Fran?ois
-- *Dave - W?LEV* -- Dave - W?LEV
|
Re: Measuring R,X Resonant Frequency
This is the typical case if mixing concepts.Its very crear that the amplifiers don?t have a 50 ohm resistor inside , un less you live in a very cold place and need some extra heating… My idea were to show that has no sense to worry about resonance and minimum SWR in this case and also consider the source impedance that differs of Z2 on VNA. The minimum SWR that shows the VNA is a calculation using the calibration standards , If you really would like to know the SWR over the transmission line there are other methods because the coaxial cables has not exactly 50 Ohms and if we condider the system as unidirectional the only purpose is to transfer the maximum power to antenna the minimum SWR must to be measured over the transmission line. In the other hand the output impedance of an amplifier don’t only define his efficiency, this is other concept mixing.
Ing. Patricio A. Greco
Taller Aeronáutico de Reparación 1B-349
Laboratorio de Calibración ISO 17025 AREA: RF/MW
Gral. Martín Rodríguez 2159
San Miguel (1663)
Buenos Aires
T: +5411-4455-2557
F: +5411-4032-0072
www.servicios-electronicos.com.ar
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Show quoted text
On 21 Jan 2025, at 13:24, Fran?ois via groups.io <18471@...> wrote:
You are right to ask yourself. There is one fundamental thing that you forget, that the TX -> line -> Antenna system is only adapted in one direction.
The antenna adaptation devices (box for example) only serve to bring 50 ohms to the TX terminals. Fortunately, the Tx does not have 50 ohms of internal impedance but only one or two ohms, otherwise the efficiency would be catastrophic.
If when looking back at your antenna you see 50 ohms, your antenna looking towards the TX does not see 50 ohms.
On the other hand, once your agreement is complete with your coupling box, if you turn the coupling box over, that is to say place 50 ohms in place of the TX and look, with a NanoVNA, through the antenna base, you will see the same impedance as that of your antenna. This is a way to preset a remote adapter.
Keep in mind that if the generator impedance is fixed you will get the maximum power out of it in a combined load (50% efficiency). But if you are left free to choose the internal impedance of the generator, whatever the load, the maximum power will come out of the generator if its internal impedance is zero (100% efficiency).
--
F1AMM
Fran?ois
|
Re: Measuring R,X Resonant Frequency
QUOTE (Jeff, G8HUL): Also with a 50ohm coax it will not be possible to alter the length to achieve a 1:1 match. Changing the length will just cause the observed impedance to travel around a constant VSWR circle on the Smith Chart, (plus or minus a very small deviation due to the changed loss from the different length of coax) ie the same VSWR but with a different phase. It is only if you used a length of coax of a different impedance that you might see a move towards the centre of the chart. All true. What I neglected to mention follows. The typical amateur SWR measuring device only taps into either voltage or current at a given (fixed) position along the feedline. If there are standing waves / reflections within the coax, Ohm's Law tells us that when the voltage decreases, the current increases, and vise-versa, such that the power is constant. Therefore, the average amateur SWR measuring device will show different reading when placed at varying positions along the XMSN line. If power were measured instead of individual voltage or current, this would not show. Dave - W?LEV On Tue, Jan 21, 2025 at 9:47?AM G8HUL via groups.io <g8hul= [email protected]> wrote: If one measures SWR in the shack considering the antenna plus feedline
(assumed coax) as a system, there is a good way to verify there is no
standing waves or reflections on the line - A totally matched system.
This
can occur if the feedline is just the right length to transform the
impedance at the antenna feedpoint to 1:1 over its length.
If that is the situation then there WILL be standing waves on the line!
The fact that the impedance is transformed at the end of the line to
50ohms does
not alter what happens on the line at the mismatch to the load. There will
still be a
reflected signal due to that mismatch. The only way that there can be no
reflected signal,
and no standing waves on the line, is if the load matches the impedance of
the coax.
Also with a 50ohm coax it will not be possible to alter the length to
achieve a 1:1 match.
Changing the length will just cause the observed impedance to travel
around a constant
VSWR circle on the Smith Chart, (plus or minus a very small deviation due
to the changed loss
from the different length of coax) ie the same VSWR but with a different
phase. It is only
if you used a length of coax of a different impedance that you might see a
move towards
the centre of the chart.
73
Jeff G8HUL
-- *Dave - W?LEV* -- Dave - W?LEV
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Re: Measuring R,X Resonant Frequency
I think also there's a confusion engendered by the term "efficiency".
Is that the efficiency inside the Tx?
Or the "efficiency" of power transfer to the antenna (i.e. Pradiated/Psupplied)?
(you'll see "antenna efficiency" as a term used to relate, for instance, the fraction of power received by a preamplifier from that incident on the antenna's Effective Area - It's not a correct usage, but there it is, and we're stuck with it)
And in any "real" system (i.e. not perfectly matched), some of the power reflected back by the antenna also gets reflected from the source back towards the antenna again. This is why systems with very low loss lines (open wire) work adequately well - especially back in the day when the amplifier had a tuning network as part of the output circuitry.
1.5:1 is -14 dB is 4% of the power is "reflected" back. (a 0.2 dB drop in the power received, compared to a 1:1) - I venture that most folks don't know or can control their system losses to a few tenths of a dB. Unless you're building radiometers or measurement systems (I've done both).
And in any case this whole "forward" and "reflected" thing is just a convenient mathematical model for analysis. One can also consider it as reactive power (which is what they do for AC line power transmission and distribution).
The other thing is that those "line loss" numbers are for an integer number of wavelengths. For HF, most of the loss is the IR losses, not dielectric losses, so it's more about the RMS current at any given point.
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-----Original Message----- From: < [email protected]> Sent: Jan 21, 2025 8:25 AM To: < [email protected]> Subject: Re: [nanovna-users] Measuring R,X Resonant Frequency You are right to ask yourself. There is one fundamental thing that you forget, that the TX -> line -> Antenna system is only adapted in one direction. The antenna adaptation devices (box for example) only serve to bring 50 ohms to the TX terminals. Fortunately, the Tx does not have 50 ohms of internal impedance but only one or two ohms, otherwise the efficiency would be catastrophic. If when looking back at your antenna you see 50 ohms, your antenna looking towards the TX does not see 50 ohms. On the other hand, once your agreement is complete with your coupling box, if you turn the coupling box over, that is to say place 50 ohms in place of the TX and look, with a NanoVNA, through the antenna base, you will see the same impedance as that of your antenna. This is a way to preset a remote adapter. Keep in mind that if the generator impedance is fixed you will get the maximum power out of it in a combined load (50% efficiency). But if you are left free to choose the internal impedance of the generator, whatever the load, the maximum power will come out of the generator if its internal impedance is zero (100% efficiency). -- F1AMM François
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Re: Measuring R,X Resonant Frequency
You are right to ask yourself. There is one fundamental thing that you forget, that the TX -> line -> Antenna system is only adapted in one direction.
The antenna adaptation devices (box for example) only serve to bring 50 ohms to the TX terminals. Fortunately, the Tx does not have 50 ohms of internal impedance but only one or two ohms, otherwise the efficiency would be catastrophic.
If when looking back at your antenna you see 50 ohms, your antenna looking towards the TX does not see 50 ohms.
On the other hand, once your agreement is complete with your coupling box, if you turn the coupling box over, that is to say place 50 ohms in place of the TX and look, with a NanoVNA, through the antenna base, you will see the same impedance as that of your antenna. This is a way to preset a remote adapter.
Keep in mind that if the generator impedance is fixed you will get the maximum power out of it in a combined load (50% efficiency). But if you are left free to choose the internal impedance of the generator, whatever the load, the maximum power will come out of the generator if its internal impedance is zero (100% efficiency).
--
F1AMM
Fran?ois
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Re: NanoVNA H4 microSD Card
Thanks Dragon,
I couldn't find anything specific in the forums, and it's not mentioned in the PDF introduction guide in the downloads section (which is otherwise excellent), so it's not quite straightforward as you may imagine it to be to find answers.
I've updated my firmware version to 1.2.27, and I can now see it in the menu.
Thanks for agreeing not to mention the book again Bill. It's particularly unhelpful just copying and pasting the same answer to everyones questions. As mentioned a number of times we have a copy at the radio club which I will browse when I next visit.
Peter
Maybe that beginners guide needs some updating.
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Re: NanoVNA H4 microSD Card
That has been discussed dozens of times before, just search the group. Anyway what seems to be your problem? Saving of screenshots works out of the box with any firmware released in the last 2 years or so. On Tue, 21 Jan 2025 at 15:44, Peter Jones via groups.io <jonesypeter@...> wrote:
I've looked online, and can find very little information on using an microSD card with this device.
Can anyone who actually owns an H4 device let me know of any information they gathered (any links appreciated). They main thing I would like to do is save screenshots when out portable.
Thanks
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Re: NanoVNA H4 microSD Card
No, but I happen to have that book on this Android smartphone. So, every time you ask for a particular type of help, I open the Kindle app, launch the book and go to the answer. Then I tell you to get the book, and then I wait for the next time. Fortunately, I'm done with that now. I won't be bothering you with news of that info source again. 73 Bill K2TNO On Tue, Jan 21, 2025, 10:00?AM Peter Jones via groups.io <jonesypeter= [email protected]> wrote: I think you must be on commission!!
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Re: Measuring R,X Resonant Frequency
At resonance the imaginary part of R ( reflection coefficient ) is null , see the attached picture. This is because Z1 is a real number. In this case 50 ohm. Its very common to see that the SWR minimum are different to resonant frequency in a dipole because the real part of Z2 also changes with frequency. The question is what is better ? Minimum SWR or Resonance. From the point of view of energy transfer the minimum SWR is the dominant concept. The antenna current and charge distribution changes over the frequency and this modifies the radiation lobes, this is how the energy goes out the antenna , at resonance you have a maximum energy concentration ( you must to consider grand planes … its complex ) when I say energy is the energy that finally left the antena this is the incident power less the reflected power. If you want to have the better results both things must to happen at the same time.
This is the theory. In practical cases the effort to get that result will imply to add a match network with components with excellent quality, have no sense. In the other hand we have the output impedance of our radio equipment and believe me this is not a real number and the real part is not exactly 50 ohm… then all fine tuning considerations are really unnecessary.
There are much to say about but, all depends on your project. The results I saw for the antenna are excellent ,SWR= 1.08 is a dreamed value.
Regards, Patricio.
Ing. Patricio A. Greco
Taller Aeronáutico de Reparación 1B-349
Laboratorio de Calibración ISO 17025 AREA: RF/MW
Gral. Martín Rodríguez 2159
San Miguel (1663)
Buenos Aires
T: +5411-4455-2557
F: +5411-4032-0072
www.servicios-electronicos.com.ar
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On 21 Jan 2025, at 11:21, Miro, N9LR via groups.io <m_kisacanin@...> wrote:
On Mon, Jan 20, 2025 at 02:43 PM, Tony Scaminaci wrote:
the load impedance must be the complex conjugate of the source impedance so Z2=R-jX Not sure that's true, but I have to admit, that's the part of SWR theory that I struggle the most
If you check formula for reflection coefficient ( R = (Z1-Z2)/(Z1+Z2) ) and any random "online calculator, all of them line up with Z1 = Z2, and not the conjugate
Conjugate assures max transfer of power as reactance's null each other (kind of a "system's resonance" of some kind). But then, expectation is that the max power transfer happens for SWR 1:1. The reason we don't see that "questioned" more often is because we all start with assumption that Z1=50, so conjugate becomes irrelevant concept :)
Hope someone here can clear that up :)
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Re: NanoVNA H4 microSD Card
I think you must be on commission!!
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Re: NanoVNA H4 microSD Card
For the very last time: Get the Kindle book NANOVNA EXPLAINED by Mike Richards, available from Amazon books. Download that digital version to any Kindle reading app...and search for "SD CARD". That's all... On Tue, Jan 21, 2025, 9:44?AM Peter Jones via groups.io <jonesypeter= [email protected]> wrote: I've looked online, and can find very little information on using an
microSD card with this device.
Can anyone who actually owns an H4 device let me know of any information
they gathered (any links appreciated). They main thing I would like to do
is save screenshots when out portable.
Thanks
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Robin Midgett
Clyde Lambert
Roger Need
Patricio A. Greco
