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Re: Comparing antenna gain process
Dr. David Kirkby from Kirkby Microwave Ltd
On Fri, 20 Sep 2019 at 18:33, Ken Buscho <kb6kob@...> wrote:
Hi, Folks, 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 |
Re: Does anyone know how sensitive the nanovna is to electrostatic discharge?
Dr. David Kirkby from Kirkby Microwave Ltd
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:diode: 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.
-- 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 |
Re: NanoVNA Saver
Hi Rune
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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 On Wed, 18 Sep 2019 at 18:05, hwalker <herbwalker2476@...> wrote:
Rune, |
Re: What options should I look for?
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. |
Re: Does anyone know how sensitive the nanovna is to electrostatic discharge?
Andy G0FTD
On Sat, Sep 21, 2019 at 01:20 AM, <qrp.ddc@...> wrote:
100% agree. There is no simple way to protect RF device with no deterioration of it'sSeems 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 |
How to read out my NanoVNA's firmware version
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 gepr¨¹ft. |
Re: NanoVNA Saver - bug report?
Hi Nick,
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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 On Fri, 20 Sep 2019 at 14:11, Nick <g3vnc@...> wrote:
Hi Rune |
Re: 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. |
Re: Firmware summary
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 |
Re: Does anyone know how sensitive the nanovna is to electrostatic discharge?
On Fri, Sep 20, 2019 at 03:46 PM, Andy G0FTD 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 There is no simple way to protect RF device with no deterioration of it's dynamic range. |
Re: Comparing antenna gain process
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. |
Re: Does anyone know how sensitive the nanovna is to electrostatic discharge?
Dr. David Kirkby from Kirkby Microwave Ltd
On Fri, 20 Sep 2019 at 13:57, Andy G0FTD via Groups.Io <punkbiscuit=
[email protected]> wrote: One other thought. 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 |
Re: NanoVNA Saver
Dr. David Kirkby from Kirkby Microwave Ltd
On Wed, 18 Sep 2019 at 21:39, Rune Broberg <mihtjel@...> wrote:
Hi David, 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 |
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