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One must wonder if you ever owned a slide rule? hihi

(Still own my eye saving yellow one by Picket)

I recently saw an article for a 20 Meter beam with dimensions in 1/10,000ths of an inch.
Someone needs to slap that lad up side of the head with a K&E slide rule!Guess he also needed to establish the exact temp the Aluminum should be at for that measurement.
"Why be approximately correct when you can be precisely wrong!"? Tom Clark W3IWI


For what it's worth, at last count I own 8 Network Analyzers.? 3 Nano's on various work benches and the big one is a 40 GHz HP 8510.? That's about 100 kg of analyzer.
On the 3 Nano's I have, one big source of uncertainty are those 50 Ohm loads.?? I had those loads on the 8510 and they were pretty bad above a few Hundred MHz.? If you can, I suggest getting a higher quality 50 Ohm load for your calibrations.?? The short and open seemed fine.? Kent

And forgets to say whether these are Imperial Gallons (defined as 4.54609l) or Queen Anne (as used in the USA) gallons (defined as 231 cubic inches—whatever an inch might have been at the time, though today the US and UK agree that an inch is 25.4?mm by definition—which is 3.785411784l.) [Thus the US gallon is about 83.27% of a UK gallon.]

Yours terribly pedantically,

Robin, G8DQX

PS: Back on topic, the joy of a wire-built antenna is that it is cheap and easy to build and *experiment* with, and one can learn a lot by just trying and seeing what happens.

On Mon, Jul 25, 2022 at 11:26 PM, Roger Need wrote:

The ini file for NanoVNA Saver is stored in this location in Windows.

C:\Users\Your user name here\AppData\Roaming\NanoVNASaver\NanoVNASaver.ini

Thanks Roger. Using Linux Mint here.

Found the file though

~/.config/NanoVNASaver/NanoVNASaver.ini

But there don't appear to be any sweep settings in that file except

SweepColor=@Variant(\0\0\0\x43\x1\xff\xff\xef\xef))))\0\0)

Please could you look at your NanoVNASaver.ini file to see if it's different on Windows.

On 7/26/22 3:09 AM, Ho-Ro wrote:

In a .S1P file it is not an impedance that is described but S11
If you want the impedances you have to recalculate them from S11

Did you see the example 9 and 10 from my posting below (out of touchstone rev 2.0 spec)?

Example 9 (Version 1.0):
!1-port Z-parameter file, multiple frequency points

Example 10 (Version 2.0):
!1-port Z-parameter file, multiple frequency points

You can for sure store also impedance in a s1p file if you calculate the Z-parameter from S-parameter - this is what my tool does, fetching S11-parameter, taking a line for line with S-parameter (freq S11.re S11.im) and creating lines of normalized Z-parameter (freq R/Z0 X/Z0) preceded by a header for Z-parameter (# HZ Z RI R 50).

While the file format spec may define formats for things other than S parameters, they're not particularly common. Not to say that they don't exist, but every tool I've used only uses S parameters.

They are, after all, called SnP files <grin>

Hey guys,

Bringing the? reactance to zero (if you really want that for your antenna), don't forget that there might be a coax cable involved in the measurement set-up.? That coax can move the Z of the antenna around the Smith Chart if the Z of the antenna is not exactly 50 ohms (ohmic).
Of course there are ways to solve that :-)

73

Arie PA3A

Op 26-7-2022 om 13:52 schreef Donald S Brant Jr:

I agree with W0LEV 100% on using the phase information to guide one's tuning efforts. That valuable phase information is what puts the "Vector" in "vector network analyzer"(VNA) and is what makes it so much more useful than just a VSWR bridge or reflectometer. Having phase information is also what allows the amazing error correction to do its magic and permit such accurate measurements in such an inexpensive instrument. The ability to do so over a swept frequency range is icing on the cake, it helps you to get a feel of the behavior of the network you are measuring.
Folks who just look at an SWR number at a single frequency are missing out on much of the capability of this tool.
73, Don N2VGU

On Tue, Jul 26, 2022 at 09:46 AM, Ho-Ro wrote:

A quick test with scikit-rf shows that it writes also in 1.1 format, but
creates only S-Parameter files, even if fed with Z-parameter:

Sorry, checked the wrong input file, scikit-rf cannot read Z-Parameter (NotImplementedError: only s-parameters supported for now.):

Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/usr/lib/python3/dist-packages/skrf/network.py", line 423, in __init__
self.read_touchstone(filename)
File "/usr/lib/python3/dist-packages/skrf/network.py", line 1752, in read_touchstone
raise NotImplementedError('only s-parameters supported for now.')
NotImplementedError: only s-parameters supported for now.

As a consequence I will name my Z-parameter files *.z1p from now on - what's your opinion?

Martin

In a .S1P file it is not an impedance that is described but S11
If you want the impedances you have to recalculate them from S11

Did you see the example 9 and 10 from my posting below (out of touchstone rev 2.0 spec)?

Example 9 (Version 1.0):
!1-port Z-parameter file, multiple frequency points

Example 10 (Version 2.0):
!1-port Z-parameter file, multiple frequency points

You can for sure store also impedance in a s1p file if you calculate the Z-parameter from S-parameter - this is what my tool does, fetching S11-parameter, taking a line for line with S-parameter (freq S11.re S11.im) and creating lines of normalized Z-parameter (freq R/Z0 X/Z0) preceded by a header for Z-parameter (# HZ Z RI R 50).

Calculation:

if format_z:
# calculate normalized impedance as Rn + jXn = R/Z0 + jX/Z0 according to this doc
#
freq, Sr, Si = line[:-1].split( ' ' )
freq = float( freq )
Sr = float( Sr )
Si = float( Si )
Sr2 = Sr * Sr
Si2 = Si * Si
Sr_2 = ( 1 - Sr ) * ( 1 - Sr )
Rn = ( 1 - ( Si2 + Sr2 ) ) / ( Sr_2 + Si2 )
Xn = ( 2 * Si ) / ( Sr_2 + Si2 )
return f'{freq:10.0f} {Rn:15.9f} {Xn:15.9f}'

Hey Doug,

If you can figure out how to build and tune an antenna with the Nano after a stroke you’re OK in my book (a retired family doc). The body may not follow all your commands but some of the brain is still working. My friend in Virginia, Guy, has had two strokes too and just serviced a QRP+ and brought it back to life. Do what you can do and pray your body and brain heal enough to enjoy this or any hobby. You need good vibes and for me ham radio provides them.

Dave K8WPE

David J. Wilcox’s iPad

When developing my nanovna mini-tools, I am unclear about the "Touchstone" file format
regarding the storage of Z-parameters for a one-port (nanovna_snp.py). So far I follow rev
1.1, it says on page 7:

In a .S1P file it is not an impedance that is described but S11

# HZ S RI R 50
6800000 0.4178235144152254 -0.6694732263322638

For each line you find in order:
Frequency in Hz
the real part of S11
the imaginary part of S11

If you want the impedances you have to recalculate them from S11
--
F1AMM (Fran?ois)

-----Message d'origine-----

De la part de Ho-Ro
mardi 26 juillet 2022 09:47

I attach simple Excel file for the same example.

It uses some of the in-built functions for dealing with complex numbers.

A complete list of available functions can be found at

Kind regards

Ed, G8FAX

Hi,



When developing my nanovna mini-tools, I am unclear about the "Touchstone" file format regarding the storage of Z-parameters for a one-port (nanovna_snp.py). So far I follow rev 1.1, it says on page 7:

Example 2:
!1-port Z-parameter file, multiple frequency points
# MHz Z MA R 75
!freq magZ11 angZ11
100 0.99 -4
200 0.80 -22
300 0.707 -45
400 0.40 -62
500 0.01 -89
Note that in the above example Z11 (the input impedance) is normalized
to 75 ohms, as given by the reference impedance (R 75) in the option
line.

Unfortunately rev. 2.0 is not totally clear about the Z format, on the one hand it is not normalized (page 7):

For Version 2.0 files, the reference resistance defines the system reference for the S-parameter data if the
[Reference] keyword is not present. Network data for G-, H-, Y- and Z-parameters in Version 2.0 files is
not normalized. Therefore, the reference resistance and [Reference] keyword have no impact on G-, H-, Y-
, or Z-parameter data in Version 2.0 files. S-parameters are, by definition, normalized with respect to the
reference impedance(s) and in this respect there is no difference between the treatment of S-parameters in
Version 1.0 and Version 2.0 files.

On the other hand, normalization of Z is mentioned in this option line example on the next page 8:

Frequency in Hz, Z-parameters in magnitude-angle format, normalized to 10 ohms:
# Hz Z MA R 10

But I suspect that this information is not correct, because further back in the document on page 14 rev 1.1 and rev 2.0 are contrasted for Z-parameters:

Example 9 (Version 1.0):
!1-port Z-parameter file, multiple frequency points
# MHz Z MA R 75
!freq magZ11 angZ11
100 0.99 -4
200 0.80 -22
300 0.707 -45
400 0.40 -62
500 0.01 -89
Note that, in the above example, Z11 is normalized to 75 ohms, as given by the reference impedance (R 75)
in the option line.

Example 10 (Version 2.0):
!1-port Z-parameter file, multiple frequency points
[Version] 2.0
# MHz Z MA
[Number of Ports] 1
[Number of Frequencies] 5
[Reference] 20.0
[Network Data]
!freq magZ11 angZ11
100 74.25 -4
200 60 -22
300 53.025 -45
400 30 -62
500 0.75 -89

This example duplicates the data in Example 9, using Version 2.0 syntax. Note that normalization does not
apply.

Question to the specialists, should one stick with rev 1.1, as does nanovna-saver, or is rev 2.0 more widely used.

A quick test with scikit-rf shows that it writes also in 1.1 format, but creates only S-Parameter files, even if fed with Z-parameter:

!Created with skrf...
# Hz S RI R 50.0
!freq ReS11 ImS11
50000.0 0.98... -0.01...
...

Martin

Thanks Ed, AG6CX,

An interesting read.

Kind regards

Ed, G8FAX

Hi Francois,

Here is a worked example in a simple way avoiding manipulations with the complex conjugate.

Based on the example at bottom of page 3 of the document.

I will start off with Zn = 2.33 + j3.33 in formula S11 = GAMMA = (Zn-1) / (Zn +1)

Step 1 Let Fr = Zn-1 and Gr = zn + 1 so S11 = F / G

Step 2. Substitute for Zn in Fr, so Fr = 2.33 + j3.33 - 1 = 1.33 + J3.33

Step 3. Convert Fr to polar form in the traditional way. I am sure you know how to do this. I do not cover this here and used a calculator

The result is Fp = 3.59 <68.23

Step 4. Substitute Zn in Gr, so Gr = 3.33 + J3.33

Step 5. Convert Gr to polar form to give Gp = 4.71 <45

Step 6. Divide in polar form S11 = Fp / Gp = 3.59 / 4.71 < 68.23 -45 = 0.7622 <23.23

Step 7. Convert polar to rectangular form in the usual way or use, like me here a calculator

S11 = 0.7 + j0.3

I hope that helps

Kind regards

Ed

Study Pilloud. You have no excuse! It’s written in French

I had already browsed this website

I did not find the text relevant and, as a result, I did not trust what I was reading there. It lacks, as often, many developments to understand. Example :

Back to top 3
It does not indicate that, in the Smith chart, the rectangular coordinates are S11. It is however the most convenient way to position an impedance on the chart, especially by software.

Bottom of page 3
We find the formula
(S11 = Zn-1)/(Zn+1) = 0.7 + j0.3
It's not educational at all. How do we go from one to the other.

Page 4 Suitably adapted line (Ligne convenablement adaptée)
It is a totally false idea, peddled from site to site and from microphone to earphone, to say that the generator must have an internal impedance of 50 ? for the line to be adapted. The adaptation is independent of the impedance of the source. Fortunately otherwise our Tx would have a deplorable performance.

Thank you for your explanations which have the merit of being much clearer
--
Fran?ois

-----Message d'origine-----

De la part de AG6CX
lundi 25 juillet 2022 22:03

Hi Doug
The 234/freq is a average, not an exact value.
The real value varies with the diameter of the wire element.
Much like the lad who puts 7 gal of petrol in his car, drives 243 miles,and says he got 34.71428532 miles per gallon.?

It's a good starting point, but you do not need to measure to fractions of an inch.
Cheers? Kent G8EMY/W5

On 7/25/22 1:38 PM, W0LEV wrote:

Also remember that a 1/4-wavelength radiator over a "perfect" image plane
(a.k.a. "ground" plane) is not 50-ohms but more like 36 ohms. So, even at
resonance, defined by +jX = - jX, the SWR will not be 1:1.

What's a lot of fun is to make a ground plane antenna, and then hook up a VNA, and watch how it changes as you bend things.

People spend a lot of time trying to build matching networks, when often, all you need is to make the angles different.

Copper foil tape on paper is another one.

Or, get a bunch of cheap telescoping whips and you can make a two (or three) element yagi and fool with different spacings, lengths, etc.

Dave - W?LEV
On Mon, Jul 25, 2022 at 7:54 PM Greg Giglio <coffeeguy2@...>
wrote:

Generally, look for where the most pronounced ‘dip’ is relative to the
frequency you’re tuning for. It should be close to what you’re looking
for. If the lowest SWR is at a lower frequency than expected, shorten the
wire. If it’s at a higher frequency, lengthen the wire.

73 de KN7GIG

"Silence is golden. Duct tape is silver."

On Jul 25, 2022, at 14:33, DOUGLAS SEWELL via groups.io <douglassewell=

[email protected]> wrote:

?Using formula 234/freq for a 1/4 wave vertical with 4 radials I was

building gave me a wire length of 16 feet 6 and 1/8 inches. Nano vna gave
swr of 2.3 (too high for my qrp station) so tried to find out whether to
shorten or lengthen wire. How can I use the nano vna to help with the
direction to go. eventually lengthened by 6 inches which brought swr down
to 1.3.

As a newbe to short wave radio tx/rx and to nano vna can anyone help

with an easy to follow method to use my nano vna for wire adjustment
direction. Thanks but difficult just now after suffering 2 strokes so hence
the need for help here.

Thanks and 73 to all who read this.
Doug MM7DSA

To those interested in Woodward's work, I found the 1953 paper that was referenced in the recent link.
Sent FYI.

Ed McCann
AG6CX
Sausalito

The ini file for NanoVNA Saver is stored in this location in Windows.

C:\Users\Your user name here\AppData\Roaming\NanoVNASaver\NanoVNASaver.ini

Roger

For those wishing to wind their own baluns or even use/test commercial ones, the following may be of interest:

Performance of balun with/without center-tap

Fundamentals of rf transformers, includes various tests of such

Test configurations and circuits for testing baluns

Kind regards

Ed G8FAX