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On Fri, 20 Sep 2019 at 18:33, Ken Buscho <kb6kob@...> wrote:

Hi, Folks,
My whole NanoVNA process started because I went out on eBay looking for an
antenna analyzer for ham VHF/UHF use and got my white model because it
intrigued me at what was being done at that price point. No prior personal
experience with VNAs, although I've been aware of them for years. Big
learning curve to get started, but it did almost everything I was looking
for once I could see SWR and a Smith Chart. It's been well worth the $60,
and I'm getting a VNA education to boot reading here.

I say almost because I would like to be able to get some values to at
least compare HT Antenna A to HT Antenna B for gain. To get started, I put
a test antenna on CH0 and a reference antenna on CH1. I can tell the CH1
antenna is "seeing" the CH0 antenna because logmag dB values change
with/without something on CH0, and I can also see that dB values go up/down
as antenna distances change.

What I'm looking for is suggestions on how to do this the right way, or at
least a better way. . Suggestions? Issues?

Appreciate the input...

Ken Buscho
KB6KOB

I don’t think you will manage just using the NanoVNA. First understand that
as hams we are interested in the far field performance. If you are working
between a few hundred kHz, the near field maybe important, but generally
you are only interested in the far field properties.

There are two ways to measure the far field gain of an antenna.

1) *Far field* measurements usually made on an antenna test range. Only the
amplitude of signals need to be measured. Amateurs can do this.

2) *Near field *measurements made in an anechoic chamber measuring both
amplitude and phase. The receiving probe needs to scan over the whole
antenna. Amplitude and phase need to be measured, so a VNA or similar is
essential. Once you have the near field pattern, the far field can be
computed by a Fourier Transform of the near field. This is totally out of
the question for hams to do - it needs very specialist equipment.

*So you need to make far-field measurements. *

In order to make far field measurements, the antennas need to be
sufficiently far apart - a distance R of

R = 2 D^2 / lambda

where D is width of the antenna.



Assuming isotopic radiators, the loss is called the free space path loss
(FSPL)



What I believe you will find is that the free space path loss will be too
high to measure with the NanoVNA. The dynamic range of the NanoVNA will not
be high enough. I suggest that you work out the distance to the far field,
then work out the attenuation in dB to check this. Adding a power amplifier
after calibration could help, but you will still probably be unable to do
it.

A more practical way will be the power output from an amateur transceiver
and a calibrated power meter, which could be a receiver. *Much* greater
attenuations can be measured this way.

I am 99.9% sure that the dynamic range of the NanoVNA will be insufficient.

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

See firmware folder

/g/nanovna-users/files/Firmware/NanoVNA%20firmware%20build%20by%20Erik/Release%200.1.1%20with%20added%20scan%20command%20and%202.1GHz.zip

On Sat, 21 Sep 2019 at 10:07, Andy G0FTD via Groups.Io <punkbiscuit=
[email protected]> wrote:

On Sat, Sep 21, 2019 at 01:20 AM, <qrp.ddc@...> wrote:

Yes, limiter diode will ruin measurement. There are two issues with

diode:

- it add parasitic reactance
- it add non-linear distortions of the signal

100% agree.

There is no simple way to protect RF device with no deterioration of it's
dynamic range.

Seems to be that way.

I had a brief research period last yesterday just to look up how others
deal with this issue.

It seems they don't, and simply practice safe procedure.

Spectrum Analysers on the other hand have much higher input levels, and do
have some
solutions, but are cannot be used in the case of a network analyser.

It obviously depends on individual instruments, but a quick check of mine
shows that the HP 8720D 20 GHz VNA I have, is *much* more tolerant of high
power & DC than my 22 GHz spectrum analyzer.

*8720D 50 MHz-20 GHz VNA*
* 40 V DC
* +30 dBm max
* No electrostatic discharge

*HP 70905A RF section of spectrum analyzer, 50 kHz to 22 GHz.*
* 0 V DC
* 15 to 30 dBm depending on the value of an internal attenuator.

Given that the attenuator in the SA is set by the the user from the
interface, I would say assuming it’s set to 0 dB is sensible, so the
maximum power is 15 dBm. That makes the power handling of the VNA 32 times
higher than the SA, and the VNA tolerating 40 V DC compared to 0 V of the
SA.

I remember my favourite instrument, a Hewlett Packard HP8594 SA having a
blown front end and getting a quote for repair.

73 de Andy

--
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

Hi Rune
V0.0.10 works fine, thank you.
May I suggest that the selection dots for the markers had a toggle function such that when these was not marked the were locked and when marked the marker was moveable. Alternative a further line called lock markers. My eager right hand fingers hit very often the left mouse key and the active marker is suddenly somewhere else.
Also if the vertical unit were scaleable would be nice e.g. to have selectable dB ranges in steps or freely selectable. Same applies for polar plot to e.g. to be able to study a load close in if inductive or capacitive or both.
Kind regards
Kurt

-----Oprindelig meddelelse-----
Fra: [email protected] <[email protected]> P? vegne af Rune Broberg
Sendt: 18. september 2019 22:36
Til: [email protected]
Emne: Re: [nanovna-users] NanoVNA Saver

I just released 0.0.10:


It's not the most exciting release, but it offers some quality of life improvements, such as the ability to choose the font size (particularly useful for Linux users, whose default is a massive 11 pt font).

It also adds debug logging: -d to get log messages to the terminal, or -D filename.txt to log to a file. Useful if you see crashes!

Additionally, it now supports importing magnitude/angle touchstone files, and there's been a number of little bugfixes.

As ever, I look forward to hearing what bugs you find, and what new features you want! :-)

--
Rune / 5Q5R

Hello,

We just uploaded the Agenda of 31st ANAMET Meeting:


and changed [.htaccess]:


Sincerely,

yin&pez@arg

1

Hi Erik
May I add the short should have a pin sitting directly onto a shorting disk which mates with the calibration plane
Kind regards
Kurt

-----Oprindelig meddelelse-----
Fra: [email protected] <[email protected]> P? vegne af erik@...
Sendt: 21. september 2019 08:30
Til: [email protected]
Emne: Re: [nanovna-users] What options should I look for?

The dummy guide to buying a nanoVNA:

This is the shop of the person that started all this and he delivers good product in excellent packaging.


But if you want to go cheaper these are your options:
Getting the calibration loads is good.
Look for those where the "open" has a hole where the "short" has a pin The cables are also nice as they allow you to have an identical test configuration as many people in this group.
Testing has shown the shielding does not realy make a difference.
Battery is very useful for testing antennas on places where you do not dare to bring a computer.
For the rest, one it arrives, test it and if you are not able to calibrate, request a refund.

On Sat, Sep 21, 2019 at 01:20 AM, <qrp.ddc@...> wrote:

Yes, limiter diode will ruin measurement. There are two issues with diode:
- it add parasitic reactance
- it add non-linear distortions of the signal

100% agree.

There is no simple way to protect RF device with no deterioration of it's
dynamic range.

Seems to be that way.

I had a brief research period last yesterday just to look up how others deal with this issue.

It seems they don't, and simply practice safe procedure.

Spectrum Analysers on the other hand have much higher input levels, and do have some
solutions, but are cannot be used in the case of a network analyser.

I remember my favourite instrument, a Hewlett Packard HP8594 SA having a blown front end and getting a quote for repair.

You could build a aircraft carrier at those prices, whence why the company was always known as High Price ;-)

In the end, I just used a buffer amplifier for general sniffing around as a precaution when it was suitable.

73 de Andy

Hi all,


There are several similar Nanovna clones on the market.
I would like to know what I have (or what perhaps not).

How do I read out my NanoVNA's firmware version?

Is there perhaps a list with info about the different versions?

Is there perhaps also a list with hardware versions?

Anything exhaustive?

Or is there no system perhaps, just chaos, as every producer does what
seems good to him without coordination with other manufacturers?

If so: Did someone try to collect all such info and make it available?


Hans, DJ7BA


---
Diese E-Mail wurde von Avast Antivirus-Software auf Viren geprüft.

Can you publish or send me your "experimental" firmware? I would like to run some tests on it.

Hi Nick,
thanks for the suggestions! Currently, I have no plans to separate the
plots from the main window, as I see them as a main feature of the
application, and want them there. The code doesn't have anything preventing
it, but I'm not personally going to work on a design that does that, as a
matter of prioritizing what time I have to work on it :-)

File pickers for load/save calibration really should have been in already,
I agree. I'll look at it :-)

And yes, you should definitely get a bigger monitor. ;-)

--
Rune / 5Q5R

The dummy guide to buying a nanoVNA:

This is the shop of the person that started all this and he delivers good product in excellent packaging.


But if you want to go cheaper these are your options:
Getting the calibration loads is good.
Look for those where the "open" has a hole where the "short" has a pin
The cables are also nice as they allow you to have an identical test configuration as many people in this group.
Testing has shown the shielding does not realy make a difference.
Battery is very useful for testing antennas on places where you do not dare to bring a computer.
For the rest, one it arrives, test it and if you are not able to calibrate, request a refund.

There are so many nanovna versions out there and the price varies quite a bit.To get the "best bang for the buck" what should I consider?
1- input shielding2- Calibration loads3- battery4- short m-m cables5- ?????
Thanks for any advice.

Hello,

We just uploaded the current version:



Sincerely,

yin&pez@arg

Forth is a niche language created for writing embedded software on very limited, bare HW. In particular, it is intended to allow you to write and test peripheral control software interactively. The STM32F072CBT6 is 2-4x the memory size of the machine Chuck Moore created it on to control the Kitt Peak radio telescope dishes and many times faster.

With so many people working on variations of the original C code. I'm not sure there is much point to my getting involved with that. Also, I think the use of threads is a major mistake from a software engineering perspective.

I have major issues with bugs and even more with code crashing, ever. Once you allow multiple independent processes to operate in the same address space, unless you use a segmented architecture al la Multics and the Intel x86 and 432, you leave yourself open to one process corrupting another.

In any case, I'm just an old man amusing himself. I've been fooling around comparing the TDR response of my 11801/SD-24 using a bare 3.5 mm connector and the nanoVNA open. There is as much difference between the two channels in both cases as there is between the bare 3.5 mm and the open.

Not quite sure how to interpret it yet. The trace calculated differences are much larger than the display suggests. That's symptomatic of small phase differences, but it's been a long time since I dealt with that and I don't remember yet how you handle it.

Have Fun!
Reg

I tested different SMA connectors with hand connection with no wrench and don't find any noticeable difference.
Probably because NanoVNA works with less than 1 GHz.

Does somebody have any confirmation that using wrenches improves measurement with NanoVNA?

On Fri, Sep 20, 2019 at 03:46 PM, Andy G0FTD wrote:

2 - Wouldn't a diode introduce capacitance across Ch0 ? Or inductive lead
effects at VHF/UHF and ruin any measurements ?

Yes, limiter diode will ruin measurement. There are two issues with diode:
- it add parasitic reactance
- it add non-linear distortions of the signal

There is no simple way to protect RF device with no deterioration of it's dynamic range.

For antenna gain measurement you're needs to place receive antenna at least half wavelength away from transmitting antenna. Otherwise your measurement will be affected by near field of antennas.

Actually the more complete way to calculate minimum distance between antennas is the following:

R = 2 * D^2 / lambda,
where:
R - minimum distance between antennas in meters
D - maximum dimension of your antenna in meters
lambda - wavelength in meters (lambda = 300 / frequency_in_MHz)

If possible place antennas at more longer distance, for example at least on 2-3 lambda. It will reduce near field influence.

Also calibrate NanoVNA through cables which you're using to connect antennas. It will reduce cable influence.

On Fri, 20 Sep 2019 at 13:57, Andy G0FTD via Groups.Io <punkbiscuit=
[email protected]> wrote:

One other thought.

During a discussion yesterday on this group, measurments were taken as to
what the OUTPUT levels were from Ch0.

They were 200mv peak to peak IIRC.

As such, I think I'd want to assume that this would be the maximum level
that any of the ports could handle and would want
to account for.

0.6v (600mv) for a basic diode to start clamping sounds a bit risky to me.

If I'm missing something here then I'm willing to learn ;-)

73 de Andy

The output level of a source is not an indication of the damage threshold.
My HP 8720D can output 10 dBm, but the damage threshold on the test ports
is I believe 30 dBm, so 100x higher.

--

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

I found some finger "wrenches" here:


and a torque limiting "wrench" here:

On Wed, 18 Sep 2019 at 21:39, Rune Broberg <mihtjel@...> wrote:

Hi David,
I don't necessarily intend to break new ground
here, and I haven't yet looked at what's the industry norm for averaged
display.

Do you have suggestions?

--
Rune / 5Q5R

I will have to look for it, but a description of the method used by HP was
posted on the Keysight forum by Dr. Joel Dunsmore. I recall him saying it
is very memory efficient as it does not require one to store all previous
values That was important when early versions of the 8753 were developed,
but far less so now.

The averaging must be done as vectors, not scalers. I will try to find out
how the professionals do this.

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