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#109 : reply to a newcomer
=
| From: "** ***" <*@gmail.com>
| Sent: Thursday, September 03, 2020 08:43
| Subject: Re: S-Parameter Uncertainties in Network Analyzer Measurements
=
| no, I am not aware of this discussion. anyway thanks for share that link.
-
errors of "error" models : /g/nanovna-users/topic/34237712
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| I would like to understand the One-Port Error Model and Calibration
| (One-Port, 3-Term Error Model).
| I`m using the attached file
-
[ Network Analyzer Error Models and Calibration Methods by Doug Rytting ]
-
| Do you know how it works? see page 11/43 (pdf).
=
| To: "** ***" <*@gmail.com>
| Sent: Thursday, September 03, 2020 15:51
=

Dear Mr. ***,

Yes, of course we are aware in our group of Doug's papers.

Well, it is a pity that you don't want to follow the suggested
discussion. Because, it was only after the intensive thinking
enforced by the demands of our participation in this very
discussion that our point of view, regarding the kind of these
measurements, was finally made absolutely clear.

Anyway, we could theoretically conclude from this discussion
the following essentials:

- (c) gin&pez@arg (cc-by-4.0) 2019 : start - - - - - - - - - -

(0) We can adopt a so-called by us "virtual"-real two-port
S-parameter "error" model, that is one consisting of a
Virtual-Measurement "Port": one that you can't see it as
really existing around, in order to connect a cable to it, and
the other, indeed a really existing one, just because you can
see it and connect a cable to it: the familiar (Under)Test Port.

(1) To arrive at this model you have * u n a v o i d a b l y *
begin with the real four-port consisting of the familiar Ports:
Input, Incident, Reflected, and (Under) Test - once again:
"real", because you can really see its four real ports and
connect cables to them.

(2) As usual, you have to write down the familiar four linear
S-parameter equations for this four-port and then -after some,
rather lengthy indeed, mathematical manipulation- to form
just one equation relating those familiar g and G ratios of
signal-samples of Reflected-to-Incident waves -g for the
Virtual-Measurement Port and G for the Real-(Under)Test Port.

(3) This equation involves 3 parameters and express the
g-Measurement in terms of G-(Under)Test, but since it is also
an invertible equation, you can also express the desired
G-(Under)Test, that is of an Unknown Load, in terms of
g-Measurement that is of the Known Network Analyzer
Readings you can see, also write down and/or collect,
as G = G(g).

(4) The involved 3 parameters, which are complicated
expressions of the four-port S-parameters mentioned above,
are those well-known (HP) "errors" - although unfortunately
enough: widely-non-understandable until now.

(5) Well, after all that said, not only here but especially in
the aforementioned discussion -currently with 292 messages-
it is also an unavoidable conclusion that for many years until now,
Doug and his colleagues at HP, also produced, under various
additional assumptions, more-or-less approximate equations
G ~= G(g) for the multi-ports of more than four ports they
considered.

- end : (c) gin&pez@arg (cc-by-4.0) 2019 - - - - - - - - - - -

That is all.

Sincerely yours,

Nikolitsa Giannopoulou
Petros Zimourtopoulos
ARG IAOI NFI
Antennas Research Group-Informal Association of Individuals-No Finance Involved-Austria-EU
:#109

"How does a 6 pin module plug into a 4 pin socket?"

There are so many possible responses! [ Not "answers" ]
- Using a 'hardware multiplexing socket' (still to be developed)
- Very carefully
- with much difficulty
- with the assistance of a suitably large hammer

Sorry, folks, I couldn't resist this one! I just wish it had been posted on April 1.

Doug, K8RFT

Here is the figure from Carter paper (1932).

Piero, I0KPT

On Wed, 2 Sep 2020 at 18:56, Miro, N9LR via groups.io <m_kisacanin=
[email protected]> wrote:

On Wed, Sep 2, 2020 at 11:34 AM, Dr. David Kirkby, Kirkby Microwave Ltd
wrote:

A full-wave dipole being an obvious example. At resonance, the VSWR is

around 100:1.

I'd disagree with this one - this is ABSOLUTELY correct, but only if "the
other" side is (normally expected) 50ohm source (TX) :)

I would disagree with that - it would also be ABSOLUTELY correct if the
reference impedance was 5000x100=500000 ohms. ?????? But both in
amateur radio and professional RF engineering, a reference impedance of 50
+ j 0 is assumed unless otherwise specified.

Dave

--

Dr. David Kirkby,
Kirkby Microwave Ltd,
drkirkby@...

Telephone 01621-680100./ +44 1621 680100

Registered in England & Wales, company number 08914892.
Registered office:
Stokes Hall Lodge, Burnham Rd, Althorne, Chelmsford, Essex, CM3 6DT, United
Kingdom

How does a 6 pin module plug into a 4 pin socket?

Larry, K4MLA

On 9/2/20 6:19 PM, Jim Lux wrote:

On 9/2/20 4:53 PM, AG6CX wrote:

The chart of impedance varying with height above ground has been around since at least 1928 or so, first published by Carter in IEE Transactions.

I’ll post the original paper, with math, when I find it. Pattern is familiar Bessel function.

Sort of.. the sine integral is zeroth order spherical Bessel, the distinction is that the usual ordinary Bessel is based on circular coordinates.
So, they're similar, but not the same -see the plot
Total getting down in the weeds here...
And I am so glad I don't have to derive this stuff from first principles any more.
For those interested in computational stuff - I highly recommend Orfandidis's textbook, which has a whole library of Matlab routines to do all this stuff (or Octave, which is a exceedingly similar free & open source product that can read and execute Matlab code)

In particular, the routines imped() and impedmat() are useful..
Chapter 25 in the book.

The plot I posted was generated using scipy:

#!/usr/bin/env python3
# -*- coding: utf-8 -*-
"""
Created on Wed Sep 2 18:02:42 2020

@author: jimlux
"""

import numpy as np
import scipy.special
import matplotlib.pyplot as plt

x = np.arange(0,4*np.pi,np.pi/50)
y1 = scipy.special.jv(0,x)

y2 = scipy.special.spherical_jn(0,x)

plt.plot(x,y1)
plt.plot(x,y2,'--')
plt.legend(["ordinary","spherical"])
plt.show()
plt.grid()
plt.xlim([0,max(x)])
plt.ylim([-0.5,1])

On 9/2/20 4:53 PM, AG6CX wrote:

The chart of impedance varying with height above ground has been around since at least 1928 or so, first published by Carter in IEE Transactions.
I’ll post the original paper, with math, when I find it. Pattern is familiar Bessel function.

Sort of.. the sine integral is zeroth order spherical Bessel, the distinction is that the usual ordinary Bessel is based on circular coordinates.

So, they're similar, but not the same -see the plot


Total getting down in the weeds here...
And I am so glad I don't have to derive this stuff from first principles any more.

For those interested in computational stuff - I highly recommend Orfandidis's textbook, which has a whole library of Matlab routines to do all this stuff (or Octave, which is a exceedingly similar free & open source product that can read and execute Matlab code)



In particular, the routines imped() and impedmat() are useful..

Chapter 25 in the book.

The chart of impedance varying with height above ground has been around since at least 1928 or so, first published by Carter in IEE Transactions.

I’ll post the original paper, with math, when I find it. Pattern is familiar Bessel function.

Ed McCann
AG6CX

The message was intended for Hugen since Magie does not respond.
Yes, I know about other groups, already a member of all of them :)

The “method of images” is given in some (all?) undergraduate EM Fields texts. I distinctly rememeber that it is treated in Collin and Plonsey. In those treatments the method is treated theoretically without specific application to antennas (IIRC).

DaveD

Because it’s not released yet?

You can also *wait* for the V2 Plus4 which will have 4 inch display, 4x

faster sweep (400 points/s), support up to 4GHz and has 70dB dynamic

range to 3GHz.

On Wed, Sep 2, 2020 at 12:36 PM David Eckhardt <davearea51a@...>
wrote:

Where can I find the V2 Plus4 of the newest design available for purchase

(3 or 4 GHz)? A www search turns up nothing.



Dave - W?LEV



On Wed, Sep 2, 2020 at 3:06 AM OwO <OwOwOwOwO123@...> wrote:

You can also wait for the V2 Plus4 which will have 4 inch display, 4x

faster sweep (400 points/s), support up to 4GHz and has 70dB dynamic

range to 3GHz.

Right now I have evaluated a few large screen V2 clones and the only one

I know performs acceptably is the 3.2 inch one. The price is trustworthy

at $100-150 for 4 inch and $70-90 for 3.2 inch, if the price is too low

they may have used worse accessories or parts.

--

*Dave - W?LEV*

*Just Let Darwin Work*







--

73,
Tripp Sanders
K5TRP

Thank you, Jim Lux!!! When in question, consult a good reference, not
hearsay or snake oil!

Kraus (undergrad) and Balanis (grad level) in any edition are golden in
this respect. For an excellent undergrad reference in general E&M theory,
try Lorrain & Corson ELECTROMAGNETIC FIELDS AND WAVES.

With the advent of the NANOVNA, some basic knowledge of EM theory is
necessary to fully exploit the capabilities of these highly capable
instruments.

Dave - W?LEV

--
*Dave - W?LEV*
*Just Let Darwin Work*

So, who drives even an end-fed half-wave (EFHW) with a 3000 or 5000 source
impedance directly???!!! The center of my Smith Charts is 50-ohms, unless
I normalize it to something else like 75, 300, or 450 ohms.

In RF engineering and all amateur transceivers, we deal almost exclusively
with 50-ohms (non-reactive). That is the source and load impedance in
transmit and receive, respectively. Evidence of the many emails and
articles in the amateur literature that deal with feeding that EFHW wire
are reflection of the task of achieving a match to these systems from a
50-ohm system impedance. 9:1, 22:1, 49:1 'baluns' or transformers? None
are the silver bullett in dealing with this high Z. It is not trivial
dealing with a good and efficient match from a resistive 50-ohms to a
resistive 3000 to 5000 ohms. All these examples are used in the amateur
community, all are quite problematic, and *all are resonant*. Yes, when
specifying SWR and 'match', the system impedance must be defined. But in
our amateur field and professional RF design and engineering, 50-ohms is
usually understood as the system impedance unless otherwise stated - no
complex portion to that Z. And I can normalize my Smith Charts to whatever
impedance I desire. The EFHW or the full-wave wire that David referred to
offer extremely high feed resistances, but are certainly resonant by
definition of zero complex portion of the feed (radiation) resistance.
The SWR in our standard 50-ohm system is still extremely high!

Dave - W?LEV

On Wed, Sep 2, 2020 at 5:56 PM Miro, N9LR via groups.io <m_kisacanin=
[email protected]> wrote:

On Wed, Sep 2, 2020 at 11:34 AM, Dr. David Kirkby, Kirkby Microwave Ltd
wrote:

A full-wave dipole being an obvious example. At resonance, the VSWR is
around 100:1.

I'd disagree with this one - this is ABSOLUTELY correct, but only if "the
other" side is (normally expected) 50ohm source (TX) :)

--
*Dave - W?LEV*
*Just Let Darwin Work*

On 9/2/20 10:02 AM, Jim Lux wrote:

On 9/2/20 8:37 AM, Dr. David Kirkby, Kirkby Microwave Ltd wrote:

On Thu, 27 Aug 2020 at 18:50, Jerry Gaffke via groups.io <jgaffke=
[email protected]> wrote:

Interesting plot here showing feed impedance vs height for a center fed

It is *exactly* the same as two coupled dipoles - just the other dipole is the "image" in the lossy soil. And yes, it's the sine and cosine integrals.
There was a reference to the math in Orfanidis's text book a few days ago. It's also in Kraus, and, I think in the ARRL antenna book or ON4UN's book.

Kraus Chapter 10 discusses mutual impedance and gives the plot - somewhere I'm sure, the "image theory" is developed, but not in that chapter.

ARRL Antenna Book chapter 8 gives same plot (Fig 20 in 20th edition)

ARRL Ant Book, Chapter 3, fig 1 shows the plot, but only up to 3/4 wavelength, and the text sort of doesn't mention the "why", just that it's due to loss. The chapter is more about effects of "ground" on verticals and far field propagation.

On Wed, Sep 2, 2020 at 11:34 AM, Dr. David Kirkby, Kirkby Microwave Ltd wrote:

A full-wave dipole being an obvious example. At resonance, the VSWR is
around 100:1.

I'd disagree with this one - this is ABSOLUTELY correct, but only if "the other" side is (normally expected) 50ohm source (TX) :)

Where can I find the V2 Plus4 of the newest design available for purchase
(3 or 4 GHz)? A www search turns up nothing.

Dave - W?LEV

--
*Dave - W?LEV*
*Just Let Darwin Work*

On 9/2/20 8:37 AM, Dr. David Kirkby, Kirkby Microwave Ltd wrote:

On Thu, 27 Aug 2020 at 18:50, Jerry Gaffke via groups.io <jgaffke=
[email protected]> wrote:

Interesting plot here showing feed impedance vs height for a center fed
dipole:




Jerry, KE7ER

I wish people would give the source of the information.
The behaviour shown looks quite believable to me. One can show that the
mutual impedance between dipoles follows a similar pattern. The formula is
fairly complicated (more than I would want to put in email), but it
includes either sine or cosine integrals (perhaps both), which shows a
similar behaviour

Note that the mutual impedance has both a real and imaginary part. I would
expect not only the real part of the impedance to show this, but also the
imaginary part.

It is *exactly* the same as two coupled dipoles - just the other dipole is the "image" in the lossy soil. And yes, it's the sine and cosine integrals.

There was a reference to the math in Orfanidis's text book a few days ago. It's also in Kraus, and, I think in the ARRL antenna book or ON4UN's book.

Dave

--

Dr. David Kirkby,
Kirkby Microwave Ltd,
drkirkby@...

Telephone 01621-680100./ +44 1621 680100
Registered in England & Wales, company number 08914892.
Registered office:
Stokes Hall Lodge, Burnham Rd, Althorne, Chelmsford, Essex, CM3 6DT, United
Kingdom

Please see inline:
On Tue, Sep 1, 2020 at 09:51 AM, Anne Ranch wrote:

Hmmm because a bunch of people want a bigger display, full stop? They don't
want remote. They don't want TWO pieces of equipment, just one.

This is one way technical discussion turns into pointless social exchange.
I DID NOT ASK FOR "FULL STOP".

I apologize if you found my "full stop" offensive. It was not meant to be. It was intended to emphasize the previous point, which I stand behind, that many people in messages in this forum asked for a larger display. You may characterize this as "social exchange" or perhaps speculation on my part but I believe there were more of those requests than for pretty much any other change, some only asked for that and some posters asked to *not* have BT/Wifi possibly due to fears about added interference and spurs. Thus: "full stop".

Yes, this thread MAY end up in pointless social exchange about who wants what
IF THE PARTICIPANTS CHOOSE TO DO SO .

In my own defence I was responding to your:

Personally - I am curious why developers spent time building bigger, more
expensive and less portable displays when adding bluetooth would let user to
use ANY size of REMOTE display for few dollars.

so I was following not leading the thread in that direction.

I vote to encourage real developers , not us social participants, to take a
serious look at implementing wireless I/O irregardless WHAT ( we guess) MASSES
"want".

OK fair enough. Let's stop the "why this not that" discussion .

PS
Last time I look there are processors with HARDWARE implementing WI-FI and/or
bluetooth "on the chip" already ...
Anybody game ?

I assume you are referring to something like an ESP which could support one or both of these?
There is, of course, no built in Wifi or BT hardware in the exisiting, standard nanoVNA-H ver3.4.
I guess my response is that the HC05 is such a device. Its is a Cambridge Silicon Radio (CSR) chip with firmware that supports serial over BT. So I guess it fits your criteria.

On Wed, 2 Sep 2020 at 17:20, David Eckhardt <davearea51a@...> wrote:

Resonance of an antenna is defined as a pure resistive component of the
feed impedance - no reactive component (the ±j). This may or may not occur
at minimum or 1:1 SWR. Amateurs still predominately equate resonance with
1:1 SWR. Please address the two parameters independently.

Dave - W?LEV

A full-wave dipole being an obvious example. At resonance, the VSWR is
around 100:1.

Resonance of an antenna is defined as a pure resistive component of the
feed impedance - no reactive component (the ±j). This may or may not occur
at minimum or 1:1 SWR. Amateurs still predominately equate resonance with
1:1 SWR. Please address the two parameters independently.

Dave - W?LEV

--
*Dave - W?LEV*
*Just Let Darwin Work*