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return loss is (almost always) a positive number. If one insists on
negative numbers, just call it s11 (or s22). In essence the same
property, but negative.

Op 4-10-2019 om 17:20 schreef Ron Spencer via Groups.Io:

I read a recent post that said that, among hams, its become the

consensus that return loss is a negative number. I respectfully disagree.

Regarding return loss, I understand some think its a negative number,

some a positive. I am in the later camp. Why? When I was a young engineer I
had the great fortune, in the early 1980s, to work for HP. Arguably the
premier test and measurement company of its time. And equally arguably a
leading if not THE leading microwave and rf company.

As new sales people, we were sent to 3, 3 week training sessions to

learn the technology and the products so we might interact with our
engineering customers in a technically sound way.

One thing HP taught, as I've said in a much earlier post, was that

return loss was always a positive number. As someone on this list pointed
out, negative loss is gain. And we KNOW that no return loss measurement, of
a passive device, can exhibit gain.

With respect, there is no gray area here. Return loss, is always a

positive (or, perhaps better said, a non- signed) number.

Even if you are at a hobby level of involvement, why not use the proper,

and correct, terminology? If you're a private pilot, you are expected/
required to use the proper terminology. Same if you are an amateur road
racer. Or "fill in your favorite" hobby.

Sent using

--

Does DfuSe_Demo_V3.0.6_Setup.exe have 30-day work limitations? Yes or no?

DMR-CLEAR_MEMORY_DFU.dfu is the only file I need to clear the memory?

Shouldn't these other files be used ?:

DMR-color-tweak-sept.29.2019_DFU.dfu

DMR_FILL Flash with FF DFU.dfu

DMR_M_10KHz_sept-13-19.dfu

DMR_nano-white-trace-test.dfu

On Fri, 4 Oct 2019 at 13:55, Rune Broberg <mihtjel@...> wrote:

If there are any miscalculations in my software, I do what I can to

correct

them. I have not recently been made aware of any problems, and at no

point

by Owen. I hope that any of you would immediately contact me, should you
find errors in NanoVNA-Saver! :-)

I have not read the article by Owen, but I would agree on this single point
about return loss. But I never commented to you, as it is a subject of much
debate. If there was a very clear majorty for one convention or the other,
I would stay you should go with it, but there's not a clear majority, so
use whatever you want.

If I was to use your software, which I might well do, but m interest is in
portable use, without external software, I would probably recompile and
change the sign. My HP LCR meter allows one to display this R+jX think in
multiple formats. I could give them to you if you wanted, but again, you
know what space you have.

While I am sending you a message, there's something else I thought of that
could be of use to many people, but you might not want to get involved in,
so I did not bother. Your software could be useful to those of us with the
very popular HP 8753 series VNA. It would be good if you could support
reading from them too. The Python code to open a GPIB code and read from it
is about 5 lines long. Much of the other commands you use to set up a
NonVNA would have an equivalent in 8753.

--

Rune / 5Q5R

--
Dr David Kirkby Ph.D C.Eng MIET
Kirkby Microwave Ltd
Registered office: Stokes Hall Lodge, Burnham Rd, Althorne, CHELMSFORD,
Essex, CM3 6DT, United Kingdom.
Registered in England and Wales as company number 08914892

Tel 01621-680100 / +44 1621-680100

Thanks. It's all very perfect. I already had these files.
But I asked other questions.

I repeat:
Does DfuSe_Demo_V3.0.6_Setup.exe have 30-day work limitations? Yes or no?

DMR-CLEAR_MEMORY_DFU.dfu is the only file I need to clear the memory?

Shouldn't these other files be used ?:
DMR-color-tweak-sept.29.2019_DFU.dfu

DMR_FILL Flash with FF DFU.dfu

DMR_M_10KHz_sept-13-19.dfu

DMR_nano-white-trace-test.dfu

Thank you again.

There has been some discussion about the best way to represent data
measured as impedance, into an equivalent circuit. The most comprehensive
of these I have seen, which my company owns, is my obsolte HP 4284A
precision LCR meter.




which is *not* a VNA, but measures the impedance of a device using a 4-wire
Kelvin measurement. This means everything shown here could conceivably be
displayed.

Someone *might* want to implement all or a subset of these. *I'm not
suggesting they are all implemented - I am just listing them for possible
discussion. *I suspect my HP 4285A LCR meter (75 kHz to 30 MHz) does the
same, but I have not checked.

*HP 4284A 1 MHz LCR meter. *
Cp-D - a parallel capacitance Cp, with a dissipation fact D
Cp-Q - a parallel capacitance Cp, with a Q of Q
Cp-G - a parallel capacitance Cp, with a conductance G
Cp-B - a parallel capacitance Cp, with a susceptance B
Cp-Rp - a parallel combination of a capacitance Cp, and resistance Rp
Cs-D - a series capacitance Cs, with dissipation factor Q
Cs-Q - a series capacitance Cs, with a Q of Q
Cs-Rs - a series combination of capacitance Cs and resistance Rs
Lp-D - a parallel inductor, with a dissipation factor D
Lp-Q - a parallel inductor, with a Q of Q
Lp-G - a parallel inductor, with a conductance of G measured in siemens
Lp-Rp - a parallel combination of an inductance Lp and resistance Rp.
Ls-Q - a series inductor Ls, with a Q of Q
Ls-Rs - a series inductor Ls with resistance Rs

*R - X - I don't need to explain what that is. *
Z-theta (degrees) - The magnitude and phase of an impedance expressed in
degrees.
Z-theta (rad) - The magnitude and phase of an impedance expressed in
radians.
G-B - G is the conductance measured in siemens (admittance Y = G + j B)
Y-theta (degrees) the magnitude of the admittance Y, and phase angle
expressed in degrees
Y-theta (rad) the magnitude of the admittance Y, and phase angle expressed
in radians

--
Dr David Kirkby Ph.D C.Eng MIET
Kirkby Microwave Ltd
Registered office: Stokes Hall Lodge, Burnham Rd, Althorne, CHELMSFORD,
Essex, CM3 6DT, United Kingdom.
Registered in England and Wales as company number 08914892

Tel 01621-680100 / +44 1621-680100