Everitt and Anner, "Communication Engineering," Third Edition, McGraw-Hill, 1956, provide a general method (pages 330-331) for examining a mismatch between a source and load, such as a transmission line feeding an antenna. They factor the source and the load into series networks, one element of which in each case is Zo, the desired impedance.
They then use "Compensation Theorem A" from page 107, which states":
"Any impedance in a network (either linear or nonlinear) may be replaced by a generator of zero internal impedance, whose generated voltage at every instant is equal to the instantaneous potential difference produced across the replaced impedance by the current flowing through it."
Using this theorem, they replace the added network segments by voltage generators so that the resultant equivalent network consists of a matched source and load with added voltage generators to represent the voltages generated by the mismatch.
I applied this to the special case of the complex conjugate load in "More Octave for Complex Zo," QEX, September/October, 2019. In that case, no modification of the source voltage or impedance is needed and the complex conjugate load is replaced by a matched load (image impedance) in series with a reactance of opposite sign that is twice the value of the reactance of the complex conjugate load's reactance. That "extra" reactance may then be replaced by a complex voltage source of zero internal impedance that will be seen to be generating a voltage that corresponds to the value of the reflected signal.
73,
Maynard
W6PAP
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On 6/26/23 23:01, Fran?ois wrote: That's it, we have converged. In my application where I am looking for an equality between a value obtained by scanning and a target value, the distance between between the two points (in the complex plane) is a much better criterion for a good result than the ROS which only complicates by creating a non-monotonic function.
When the result of the calculation is equal to the target, the ROS is indeed ONE and the distance zero. It is in the search for the optimal that the ROS disrupts everything.
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Re: NanoVNA with bigger screen
nanovna v2plus4, lite vna64, nanovna h4, nanovna -F V2, etc etc
there are a handful of vna and vna v2 with 4 inch or 4.3 inch screens
i recommend to use one of the newer v2 models that go up to 3 or even up to 6 ghz cause the older models (1.5ghz) only have a clock up to 300mhz and above that (900mhz or 1.5ghz) is measured in harmonic mode (with reduced sensitivity and dynamic range) ... the newer v2 models are much better on the higher frequency area
maybe a lite64 is for you?? or a plus4 or ... a vna6000??? (a bit expensive in my view)
greetz sigi dg9bfc
ps an option is to buy a cheaper version and add a 4 inch screen to it ... just needs the fw for that bigger screen to be uploaded in the device
Am 28.06.2023 um 04:45 schrieb Pedro Madeira CT7AHV:
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Hello to all
Recently I saw a nanoVNA somewhere with a bigger screen than the normal 3 inches.
Can someone tell me the model please?
Thanks in advance
73
Pedro Madeira
CT7AHV/C91AHV
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Re: NanoVNA with bigger screen
On 28/06/2023 03:45, Pedro Madeira CT7AHV wrote: Hello to all
Recently I saw a nanoVNA somewhere with a bigger screen than the normal 3 inches.
Can someone tell me the model please?
Thanks in advance
73 Pedro, There are several, but the "LiteVNA 64" has coverage up to 6 GHz and gets good reviews and comments here. If 2 GHz is enough try the NanoVNA H4 Beware of clones.... 73, David GM8ARV -- SatSignal Software - Quality software for you Web: Email: david-taylor@... Twitter: @gm8arv
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Re: Transmission Line Tools
Problem solved, TLW3 works ok.
Robert
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Re: NanoVNA with bigger screen
Pedro, most probably it was an nanoVNA-H4 ( /g/nanovna-users/wiki#NanoVNA-H4) There are other possibilities, but they are more expensive. HTH, 73, Stay Safe, Robin, G8DQX
On 28/06/2023 03:45, Pedro Madeira CT7AHV wrote: Hello to all
Recently I saw a nanoVNA somewhere with a bigger screen than the normal 3 inches.
Can someone tell me the model please?
Thanks in advance
73
Pedro Madeira
CT7AHV/C91AHV
|
NanoVNA with bigger screen
Hello to all
Recently I saw a nanoVNA somewhere with a bigger screen than the normal 3 inches.
Can someone tell me the model please?
Thanks in advance
73
Pedro Madeira
CT7AHV/C91AHV
|
Ah, the old days! It's been 50 years since I've used a GDO (when G = grid!).
I'll give that a go, thanks.
--
Mike
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On Tue, Jun 27, 2023 at 05:54 AM, Mike wrote: I compared both methods of calibration, which I refer to as "screws" and
"crocs".
At around 72kHz, where the reactance is approximately 50R, both calibration
methods give an inductance of 108uH. However, the SRF was 7.4MHz for "screws"
and 12.9MHz for "crocs".
I then repeated the measurement with a different VNA, an FA-VA5. This gave
L=110.7uH for "screws" and 110.5uH for "crocs". The SRF was 6.38MHz for
"screws" and 6.45MHz for "crocs".
I can accept the difference in L between the two devices but can't decide
which one is giving me the most accurate SRF. With a 110 uH coil it takes 4.2 pF to resonate at 7.4 MHz. and 1.4 pF to resonate at 12.9 MHz. That is a difference of 2.8 pF which is not much. One way to get to the bottom of this is to short the terminals of the coil together and then "grid dip" it like the old days. You can do this with the NanoVNA by making a pickup coil at the end of a short connecting cable. Calibrate over 5 to 15 MHz. in the usual manner. Set the trace to S11 Log (Return Loss setting) Then attach the pickup coil to the NanoVNA and place the 110 uh coil and the pickup coil in parallel a short distance apart. Look for a dip in the trace. Keep moving the coil further away until the dip has just about disappeared. Now move a marker to the dip and the frequency should be very close to the SRF. Roger
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Re: Transmission Line Tools
On Tue, Jun 27, 2023 at 04:23 PM, Robert wrote: I have a PC with Windows 7 Pro SP1 32bit (German).
C:\windows\SysWOW64 does not exist on my OS, and your batch file reports an
error.
On my 2 other Win10 64bit PCs TLW3 works ok after running TLW3-Install.bat.
I get the Error 339 when I exit TLW3.
My batch file is for 64 bit systems only. Try manually copying TeeChart5.ocx to C:\WINDOWS\system32 Then run TLW3.exe Roger
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Re: Transmission Line Tools
Hello Roger,
I have a PC with Windows 7 Pro SP1 32bit (German).
C:\windows\SysWOW64 does not exist on my OS, and your batch file reports an error.
On my 2 other Win10 64bit PCs TLW3 works ok after running TLW3-Install.bat.
I get the Error 339 when I exit TLW3.
Help is much appreciated.
73, Robert W4BCZ
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What I wanted to do is not working.
I have an Excel sheet that allows me from the S11 of an antenna to determine its L and C near the resonance by pressing the curve of a plug to pass through two points.
In your case, it works at resonance but we already know the values involved. Far from resonance the results are not good.
--
Fran?ois
De la part de Mike
Envoy¨¦ : mardi 27 juin 2023 15:00
|
On Tue, Jun 27, 2023 at 09:02 AM, Fran?ois wrote:
Could you post your .s1p file in shunt on port 0. I would like to reger
something.
Have you noticed that when you connect a coil or a trap (finally a dipole) by
a single leg on port 0 (the other leg in the air), looking at the ROS, you can
see the resonance very well. Ok, it only gives elements at the resonance
frequency... but still it's very practical
73
--
F1AMM
Fran?ois
-----Message d'origine----- De la part de Mike
Envoy¨¦ : lundi 26 juin 2023 10:23
Hi Fran?ois Here is the .s1p file for a range of 1 to 20MHz. -- Mike G8GYW
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On Mon, Jun 26, 2023 at 05:25 PM, Roger Need wrote: I suggest you calibrate right at the screw terminations on the green block
with the alligator clip leads removed. Then attach the leads and make your
measurement. From the photo it looks like the leads are about 4" long and
each one will add about 100 nH of inductance (total 200 nH or 0.2 uH). That
extra .2 uH when you are measuring 110 uH is not significant. However you
should get a better estimate of the SRF and be able to calculate the parasitic
capacitance to more accuracy.
Try it and see what you find...
Roger
Roger I compared both methods of calibration, which I refer to as "screws" and "crocs". At around 72kHz, where the reactance is approximately 50R, both calibration methods give an inductance of 108uH. However, the SRF was 7.4MHz for "screws" and 12.9MHz for "crocs". I then repeated the measurement with a different VNA, an FA-VA5. This gave L=110.7uH for "screws" and 110.5uH for "crocs". The SRF was 6.38MHz for "screws" and 6.45MHz for "crocs". I can accept the difference in L between the two devices but can't decide which one is giving me the most accurate SRF. -- Mike
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Re: nanovna-saver crashes with H4
That is a very old version of NanoVNA Saver, download the latest
version and try again.
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Show quoted text
On Mon, 26 Jun 2023 at 23:07, Fred Moore <n40cla@...> wrote:
I am confused. A friend of mine and I are trying to figure out why *my
nano H4 and his very early nano vna with the 2.8" screen will both run on
his nano saver 0.3.7.* His 2.8 nano runs on my computer on saver 0.3.8 but
mine does not. My w10 system complains about
*Error during sweep*
*Stopped*
*Failed to read data 1 10 times*
*Data outside expected valid ranges, or in unexpected format.*
*You can disable validation on the device settings screen.*
This just happened in the last couple of days. I have both 0.3.7 and 0.3.8
on my W10 system and this problem exists on both saver versions.
Help
Fred - N4CLA
On Thu, Dec 17, 2020 at 9:00?AM GM4OSS <stevegm4oss@...> wrote:
Hi
I'm new to this group and just received a nanovna H4. When I launch nano
saver V 0.3.80 on (W10 PC) it sees the H4 (Com 5) and after I click
'Connect to Device' the software crashes.
I did notice from the nano-saver.exe the following message before crashing.
'Did not recognise nanovna device from firmware'.
Help please - is there a work around?
--
73 de Steve GM4OSS
|
Could you post your .s1p file in shunt on port 0. I would like to reger something.
Have you noticed that when you connect a coil or a trap (finally a dipole) by a single leg on port 0 (the other leg in the air), looking at the ROS, you can see the resonance very well. Ok, it only gives elements at the resonance frequency... but still it's very practical
73
--
F1AMM
Fran?ois
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Show quoted text
-----Message d'origine----- De la part de Mike Envoy¨¦ : lundi 26 juin 2023 10:23
|
Re: Outliers in group delay measurement
Here it is, thanks for taking a minute to look into it. Attachments : - your smoothed file - the processing log (.CSV) showing the anomalies detected. - the S21 Group Delay (ns) on the smoothed file 73 -- F1AMM Fran?ois De la part de astech119 Envoy¨¦ : lundi 26 juin 2023 20:24
|
That's it, we have converged. In my application where I am looking for an equality between a value obtained by scanning and a target value, the distance between between the two points (in the complex plane) is a much better criterion for a good result than the ROS which only complicates by creating a non-monotonic function.
When the result of the calculation is equal to the target, the ROS is indeed ONE and the distance zero. It is in the search for the optimal that the ROS disrupts everything.
--
F1AMM
Fran?ois
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Show quoted text
-----Message d'origine----- De la part de Maynard Wright, P. E., W6PAP Envoy¨¦ : mardi 27 juin 2023 00:56
|
Re: nanovna-saver crashes with H4
Thanks for the info. I do NOT use usc-c to usb-c cables. I use the
standard original usb-a to usb-c. Can you provide a link for the latest
DiSLord code?
Thanks
Fred
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On Mon, Jun 26, 2023 at 7:57?PM Stan Dye <standye@...> wrote: I had a similar problem when I had a bad cable or a bad port connection.
Try a different cable, or a different port on the computer. Don't use a
usb-c to usb-c cable, use a usb-a port on your computer.
The DiSlord 1.0.64 firmware is a bit old, but is a known good version with
no bugs that I know of. More recent firmware has more features, but
shouldn't affect basic operations.
On Mon, Jun 26, 2023 at 3:42?PM Fred Moore <n40cla@...> wrote:
I forgot to mention that the nano 2.8 hardware is on some old software. My
H4 software is also old 1.0.64. It was installed May 31 2021
Fred
On Mon, Jun 26, 2023 at 5:19?PM Tim Dawson <tadawson@...> wrote:
What code version(s) are on the NanoVNA's?
On Mon, June 26, 2023 5:06 pm, Fred Moore wrote:
I am confused. A friend of mine and I are trying to figure out why *my
nano H4 and his very early nano vna with the 2.8" screen will both
run
on
his nano saver 0.3.7.* His 2.8 nano runs on my computer on saver
0.3.8
but mine does not. My w10 system complains about
*Error during sweep*
*Stopped*
*Failed to read data 1 10 times*
*Data outside expected valid ranges, or in unexpected format.*
*You can disable validation on the device settings screen.*
This just happened in the last couple of days. I have both 0.3.7 and
0.3.8
on my W10 system and this problem exists on both saver versions.
Help
Fred - N4CLA
On Thu, Dec 17, 2020 at 9:00?€?AM GM4OSS <stevegm4oss@...>
wrote:
Hi
I'm new to this group and just received a nanovna H4. When I launch
nano saver V 0.3.80 on (W10 PC) it sees the H4 (Com 5) and after I
click 'Connect to Device' the software crashes.
I did notice from the nano-saver.exe the following message before
crashing. 'Did not recognise nanovna device from firmware'.
Help please - is there a work around?
--
73 de Steve GM4OSS
--
Tim Dawson (tadawson@...) Owner/Engineer
TPC Services Bellnet:
(906)-482-5732
Houghton, MI 49931
"The world is complex. Sendmail.cf reflects this...."
|
Re: nanovna-saver crashes with H4
I had a similar problem when I had a bad cable or a bad port connection.
Try a different cable, or a different port on the computer. Don't use a
usb-c to usb-c cable, use a usb-a port on your computer.
The DiSlord 1.0.64 firmware is a bit old, but is a known good version with
no bugs that I know of. More recent firmware has more features, but
shouldn't affect basic operations.
toggle quoted message
Show quoted text
On Mon, Jun 26, 2023 at 3:42?PM Fred Moore <n40cla@...> wrote: I forgot to mention that the nano 2.8 hardware is on some old software. My
H4 software is also old 1.0.64. It was installed May 31 2021
Fred
On Mon, Jun 26, 2023 at 5:19?PM Tim Dawson <tadawson@...> wrote:
What code version(s) are on the NanoVNA's?
On Mon, June 26, 2023 5:06 pm, Fred Moore wrote:
I am confused. A friend of mine and I are trying to figure out why *my
nano H4 and his very early nano vna with the 2.8" screen will both run on
his nano saver 0.3.7.* His 2.8 nano runs on my computer on saver 0.3.8
but mine does not. My w10 system complains about
*Error during sweep*
*Stopped*
*Failed to read data 1 10 times*
*Data outside expected valid ranges, or in unexpected format.*
*You can disable validation on the device settings screen.*
This just happened in the last couple of days. I have both 0.3.7 and
0.3.8
on my W10 system and this problem exists on both saver versions.
Help
Fred - N4CLA
On Thu, Dec 17, 2020 at 9:00?€?AM GM4OSS <stevegm4oss@...>
wrote:
Hi
I'm new to this group and just received a nanovna H4. When I launch
nano saver V 0.3.80 on (W10 PC) it sees the H4 (Com 5) and after I
click 'Connect to Device' the software crashes.
I did notice from the nano-saver.exe the following message before
crashing. 'Did not recognise nanovna device from firmware'.
Help please - is there a work around?
--
73 de Steve GM4OSS
--
Tim Dawson (tadawson@...) Owner/Engineer
TPC Services Bellnet:
(906)-482-5732
Houghton, MI 49931
"The world is complex. Sendmail.cf reflects this...."
|
R. A. Chipman, in "Schaum's Outline Series - Theory and Problems of Transmission Lines," McGraw-Hill, 1968, points out that when a lossy transmission line has Zo complex, minimum reflection from the load will occur when Zt equals Zo but maximum power transfer will occur when Zt is the complex conjugate of Zo. This seems nonituitive, but Chipman explains that the voltage and current relationships in the two or three eighth wavelengths adjacent to the load cause the loss of power to be reduced by exactly the amount necessary to provide the extra power required in the load (page 139).
Chipman also shows that when Zo is complex, it is possible for the reflection coefficient to be greater than 1. He shows that the maximum value for the reflection coefficient is 1 + sqrt(2) (page 137) and states on page 138:
"The conclusion is somewhat surprising, though inescapable, that a transmission line can be terminated with a reflection coefficient who magnitude is as great as 2.41 without there being any implication that the power level of the reflected wave is greater than that of the incident wave."
In radio work, we often assume that a lossy line has a real characteristic impedance and this is a useful approximation in most cases. Chipman points out that the relationships among the primary constants make that relationship mathematically impossible except for a line (impractical physically) for which the loss due to R equals the loss due to G.
73,
Maynard
W6PAP
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On 6/26/23 07:58, Jim Lux wrote: On 6/26/23 7:26 AM, Fran?ois wrote:
I knew about the phone lines. My problem is that if we calculate the S11 with complex values, it leads, for example, to a ROS which can be negative. S11 is no longer in a circle of radius 1.
Is this normal or am I mistaken? It's possible, that with some active systems, you could get a reflection that is bigger than the incident wave (i.e. if the Zload were negative). ?But I think that for an entirely passive load, the reflected wave cannot be greater than the incident wave.
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David J Taylor
Roger Need
