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Re: Use of Outer Conductor on NanoVNA-H4
Hi All,
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Yes, let us all practice respect and tolerance. We come from many backgrounds and levels, and what is great about this group is that we can all learn from each other, and help each other. Like many technical fields, our field uses a technical jargon which takes ordinary words from our everyday vocabulary, like "port", and attaches to it a specific technical definition. For insiders, this is very convenient and time saving, and we take it for granted. But for neophytes, or simply those who have not been schooled in the jargon, the jargon can be a barrier. So, for the specific case in point, in circuit theory jargon, a "port" is defined as two connection points to a circuit. For many circuits, it is convenient to define various pairs of connection points as "ports". For many circuits, it is convenient to define only two connection points, and to call this circuit a "1-port" circuit. In many other circuits, it is convenient to defines two pairs of connection points, i.e. 2 ports. Often it is convenient to think of one of them as an input, and the other as an output, but in theory there is no fundamental difference. (In practice, you wouldn't want to excite a power amplifier 2-port at its output!). And in other circuits, it is convenient to designate multiple ports. The nanoVNA allows us to characterize 1-port and 2-port circuits, as the "device under test" (DUT). These two designated points are connected by the shield and central conductor of the SMA coaxial connectors on the nanoVNA. Hope this helps! Regards, Ray 4X1RB From the home of Prof. Emeritus Raymond (Reuven) Boxman School of Electrical Engineering Tel Aviv University Cell: ???? +972 544 634 217 CEO Clear Wave Ltd.? ????????????? Scientific Writing Courses: ??????? -----Original Message-----
From: [email protected] <[email protected]> On Behalf Of Andrew Kurtz via groups.io Sent: ????? 13 ?????? 2021 03:15 To: [email protected] Subject: Re: [nanovna-users] Use of Outer Conductor on NanoVNA-H4 Here is a quote from P. 14 of the Absolute Beginner¡¯s Guide to NanoVNA found at your site: "When measuring one port devices, such as an antenna or individual components, the VNA transmits a signal of known magnitude and frequency from it's Port 1 into the DUT and measures magnitude and phase of the reflected signal from the DUT on the same port, VNA Port 1.¡± Doesn¡¯t that phrase ¡°1 port device¡± suggest a single input? My antenna has a single wire going outside; where would I find some other signal to attach to the outer conductor of the small SMA on the VNA? Please don¡¯t reply if you want to tell me I am an idiot and still not help me out. Andy On Aug 12, 2021, at 1:57 PM, David Eckhardt <davearea51a@...> wrote: |
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Re: Use of Outer Conductor on NanoVNA-H4
Andy, you wrote:
¡® Doesn¡¯t that phrase ¡°1 port device¡± suggest a single input? ¡® A port has two terminals (signal and reference). If you are attempting to determine the inductance of a component, a shunt connection between the signal terminal (coax center terminal) and the reference terminal (coax connector body) will get you what you are after. While you will get some measured s-parameters if you don¡¯t have the reference terminal connected they won¡¯t be correct. Regards, Ray WB6TPU |
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Re: Use of Outer Conductor on NanoVNA-H4
On 8/12/21 5:15 PM, Andrew Kurtz via groups.io wrote:
Here is a quote from P. 14 of the Absolute Beginner¡¯s Guide to NanoVNA found at your site: This is a classic question on "wire" antennas (think a whip on an HT - the shield on the coax connector goes nowhere).? "the other wire" is there, it's just not at the connector. It's in the stray capacitance of the measurement device to your hand, bench, or surroundings. In the case of classic "long wire" antennas, often there is a separate connection to a ground rod (or ground radials, or a cold water pipe).. but lots and lots of radios (such as the Nano spectrum analyzer) have the "ground" as "capacitance to surroundings". It's what makes measuring performance of such antennas challenging - the person (or fixture) holding the radio is part of the antenna. |
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Re: Use of Outer Conductor on NanoVNA-H4
On 8/12/21 5:08 PM, Andrew Kurtz via groups.io wrote:
OK, I will ignore the rectum who likes to insult and bluster without adding an iota of value to the conversation. I have attached a single alligator clip to the pin of CH0 and to one end of an inductor. I can put a second alligator clip to the pin of CH1 and to the other end of the coil, or I don¡¯t have to. Either way, a signal goes into the inductor from CH0 and is reflected, and the nanoVNA correctly reports the inductance as part of the Smith chart and correctly shows that transmission to CH1 falls off as frequency rises. I believe it is working well, because I calibrated it carefully. There is nothing on the outer conductor of either CH0 or CH1. Do you think I would have better or more confidence results if I attached something to the outer conductor? I don¡¯t even see anything that I could attach there from my coil¡Sure, it works. the "shield" connection is via the PWB.? You *might* see a difference if you ran a piece of wire from connector shield to connector shield that is parallel with your inductor and test jig. (because forcing the current to flow "around" the loop increases the inductance slightly).? And, of course, calibration is a bit iffy - that is, doing the cal establishes a "calibration plane" at some place, and that assumes that all the currents are flowing "outside" the plane. S11 should be the inductor in series with the 50 ohm termination at CH1. S21 is the series combination of the 50 ohm source, the inductor, feeding the 50 ohm load. |
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Re: Use of Outer Conductor on NanoVNA-H4
Andy,
You are doing it right as the outer conductor is connected through the nanoVNA. The way I do it though is to mount two SMA jacks on a piece of single-sided PCB and have two short wires with alligator clips to the center pins of the connectors. There are other ways to connect components to be measured to the nanoVNA. You can just connect them across ch0 or you can connect them across a connection between ch0 and ch1. Gary W9TD |
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Re: Use of Outer Conductor on NanoVNA-H4
Over what frequency and targeted value of inductance are you measuring? If
you just want the inductance, it would be appropriate to connect the inductor across the source port, Channel 0, only. One end of the inductor goes to the center conductor of Ch 0 and the other end of the inductor goes to the backshell of that connector. The inductance should be relatively constant with frequency until you approach self resonance of the inductor. Then it should dip close to zero, and above self resonance, become capacitive. No real need to connect the inductor between the source port (Ch 0) and the sink or receive port (Ch 1). Dave - W?LEV On Fri, Aug 13, 2021 at 12:08 AM Andrew Kurtz via groups.io <adkurtz= [email protected]> wrote: OK, I will ignore the rectum who likes to insult and bluster without-- *Dave - W?LEV* *Just Let Darwin Work* |
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Re: Use of Outer Conductor on NanoVNA-H4
Andrew Kurtz
Here is a quote from P. 14 of the Absolute Beginner¡¯s Guide to NanoVNA found at your site:
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"When measuring one port devices, such as an antenna or individual components, the VNA transmits a signal of known magnitude and frequency from it's Port 1 into the DUT and measures magnitude and phase of the reflected signal from the DUT on the same port, VNA Port 1.¡± Doesn¡¯t that phrase ¡°1 port device¡± suggest a single input? My antenna has a single wire going outside; where would I find some other signal to attach to the outer conductor of the small SMA on the VNA? Please don¡¯t reply if you want to tell me I am an idiot and still not help me out. Andy On Aug 12, 2021, at 1:57 PM, David Eckhardt <davearea51a@...> wrote: |
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Re: Use of Outer Conductor on NanoVNA-H4
Andrew Kurtz
OK, I will ignore the rectum who likes to insult and bluster without adding an iota of value to the conversation. I have attached a single alligator clip to the pin of CH0 and to one end of an inductor. I can put a second alligator clip to the pin of CH1 and to the other end of the coil, or I don¡¯t have to. Either way, a signal goes into the inductor from CH0 and is reflected, and the nanoVNA correctly reports the inductance as part of the Smith chart and correctly shows that transmission to CH1 falls off as frequency rises. I believe it is working well, because I calibrated it carefully. There is nothing on the outer conductor of either CH0 or CH1. Do you think I would have better or more confidence results if I attached something to the outer conductor? I don¡¯t even see anything that I could attach there from my coil¡
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Andy On Aug 12, 2021, at 1:57 PM, David Eckhardt <davearea51a@...> wrote: |
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Re: Use of Outer Conductor on NanoVNA-H4
Simple circuit theory taught in HS physics, and even some HS algebra
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classes, teach this concept!! This is even hands-on demonstrated to grade schoolers in the Fort Collins, Colorado Museum of Science and Discovery. Yes, grade schoolers! OK, no more roasting and flaming, but certainly our present educational system has fallen flat on its face!! Dave - W?LEV On Thu, Aug 12, 2021 at 5:49 PM G8DQX list <list@...> wrote:
Andy, --
*Dave - W?LEV* *Just Let Darwin Work* |
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Re: Use of Outer Conductor on NanoVNA-H4
Andy,
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please forgive me suggesting that the below is a truly bizarre interpretation. For all practical purposes anything connected to an SMA connector implicitly requires two connections: a) a coaxial outer, and b) a coaxial inner. If the coaxial outer is not connected, then the return path from the inner pin is pretty much a matter of good, more probably bad, luck, written undefined for short. Always use a coax connection to whatever it is one is trying to measure, even if using a special test fixture, such as when looking at chokes or crystals. Then all the current flow paths are well-defined. HTH, 73, Stay Safe, Robin, G8DQX On 12/08/2021 16:25, Andrew Kurtz via groups.io wrote:
All discussions of the NanoVNA suggest that the pin on the SMA connector attached to channel 0 is the only connection needed to look at reflection (S11). |
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Re: Use of Outer Conductor on NanoVNA-H4
Every filter has a ground path. How would you connect a filter with only
one lead? Is it going to be used like that in a circuit? All the filters I've built have a BNC, N or SMA connector for input and output. The input connects to the CH0 connector and the output connects to the CH1 connector. I use the SMA cables supplied with the NanoVNA and any needed adaptors. Simple components have two leads. However you do it, connect one lead to the center pin of CH0 and the other lead to ground. I've used two alligator clips on wires soldered to the ends of a small piece of coax connected to the CH0 connector for lower frequency measurements. You may need a test jig for higher frequencies. Zack On Thu, Aug 12, 2021 at 12:18 PM Andrew Kurtz via groups.io <adkurtz= [email protected]> wrote: Yes, this does make sense¡ except what then do you connect to the outer |
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Re: Use of Outer Conductor on NanoVNA-H4
Guys and gals, think, just think! Every circuit requires a return. If you
connect only the center conductor or coax to anything, the "return" becomes the surrounding environment. This is coupled from the radiated fields of the center conductor. Please,....supply a return form the currents launched onto the center wire. Yes, absolutely, supply a return in the form of connecting the coax braid or outer conductor to the outside of the SMA or N connector!! Without that, you don't have a proper return against which the instrument can make a correct measurement. Take an AA battery. Just sitting on the shelf, there is a lot of energy stored chemically. But that's all that can happen unless you supply a 'return' from the positive to negative terminals. Then and only then, does current flow and the chemical energy is immediately converted to electrical energy in the form of current flow. Without that conductor, nothing happened. This is a simplistic model for HF circuits, but it illustrates the requirement for supplying a return for intended currents. The currents can't happen without a connectiion between the two terminals of the battery. Same with HF RF currents. Ohm's Law says the same thing. V = IR. With no current, voltage is zero. Dave - W?LEV On Thu, Aug 12, 2021 at 3:40 PM Andrew Kurtz via groups.io <adkurtz= [email protected]> wrote: All discussions of the NanoVNA suggest that the pin on the SMA connector-- *Dave - W?LEV* *Just Let Darwin Work* |
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Re: Use of Outer Conductor on NanoVNA-H4
Andy - build yourself a test fixture or buy one like this that connects to the SMA connectors:
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/g/nanovna-users/photo/0/34671.14120.0?p=Taken,,,20,1,340,0 On Thursday, August 12, 2021, 1:18:07 p.m. EDT, Andrew Kurtz via groups.io <adkurtz@...> wrote:
Yes, this does make sense¡ except what then do you connect to the outer connector when analyzing a filter or some other simple component.? The center pin on CH0 goes in, and there is nothing left to connect to the outer conductor. Andy On Aug 12, 2021, at 11:45 AM, Zack Widup <w9sz.zack@...> wrote: |
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Re: Nano VNA Interface to a Mac
On 8/12/21 8:20 AM, Andrew Kurtz via groups.io wrote:
Does anyone know how to interface a NanoVNA-H4 to a Mac? Everything I read is based on a PC with Windows or Linux¡ Just connect the cable? to the USB-C port on the VNA - I have a Mac and use NanoVNA-Saver, which is python and uses the pyserial library.? The Windows apps, of course, won't do you much good unless you run a windows VM.? If you want a simpler interface (e.g. to script) then there's nanovna.py. |
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Re: Use of Outer Conductor on NanoVNA-H4
Andrew Kurtz
Yes, this does make sense¡ except what then do you connect to the outer connector when analyzing a filter or some other simple component. The center pin on CH0 goes in, and there is nothing left to connect to the outer conductor.
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Andy On Aug 12, 2021, at 11:45 AM, Zack Widup <w9sz.zack@...> wrote: |
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Re: Nano VNA Interface to a Mac
Andy - search the messages on the forum for 'mac' and you'll find the info you need.
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There are a large number of message threads regarding this and the various versions of MacOS along with using the NanoVNA-Saver application. On Thursday, August 12, 2021, 11:40:26 a.m. EDT, Andrew Kurtz via groups.io <adkurtz@...> wrote:
Does anyone know how to interface a NanoVNA-H4 to a Mac?? Everything I read is based on a PC with Windows or Linux¡ Thanks. ? Andy |
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Re: Download NanaoVNA Labview
Syd
I have a LabVIEW version installed on my laptop, but see that there is a cheaper, $50 version now available to the public, making it even more accessible to the Ham community. Since you spent a good deal of time developing this project, it would be a shame to not share it with the Ham community. There are a few open source forums that you could download this project to and let the community take it from there. This NanoVNA thing is going to take off and be very popular because now it is accessible to the general population of electronics enthusiasts. And your software would be well appreciated now that we have seen it in action.
syd/wt1v/EE |
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Re: Use of Outer Conductor on NanoVNA-H4
I look at that as sort of like trying to apply DC power through only one
lead. I always use connections through both the center connector and shield of the NanoVNA. Zack W9SZ On Thu, Aug 12, 2021 at 10:40 AM Andrew Kurtz via groups.io <adkurtz= [email protected]> wrote: All discussions of the NanoVNA suggest that the pin on the SMA connector |
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Re: Nano VNA Interface to a Mac
Il 12/08/21 17:20, Andrew Kurtz via groups.io ha scritto:
Does anyone know how to interface a NanoVNA-H4 to a Mac? Everything I read is based on a PC with Windows or Linux¡yes Andy, use a simple software minicom. Download it, and use this command in a IOS terminal: minicom -D /dev/ttyACM0 '73 de Paolo IV3BVK -- Paolo Garbin - IV3BVK - K1BVK WW LOC JN65GX - 33074 Fontanafredda (PN) Inviato con Thunderbird su Distribuzione Linux random Nota di riservatezza / Confidentiality note Il messaggio pu¨° contenere informazioni strettamente confidenziali, urgenti e coperte da segreto professionale. Salvo che non sia espressamente autorizzato ¨¨, pertanto, strettamente proibito qualsiasi uso, comunicazione, copia o diffusione non autorizzata dei contenuti di questo documento. La diffusione, distribuzione e/o copiatura dei documenti trasmessi da parte di qualsiasi soggetto diverso dal destinatario ¨¨ proibita sia ai sensi dell'art. 616 c.p. sia ai sensi del D.Lgs. 196/2003. Nel caso in cui abbiate ricevuto per errore la presente comunicazione, vogliate cortesemente darcene immediata notizia e cancellare questo messaggio dal Vostro sistema. In ogni caso, il mittente, in ragione del mezzo di trasmissione utilizzato, non assume alcuna responsabilit¨¤ in merito alla segretezza e riservatezza delle informazioni contenute nel presente messaggio e nei relativi allegati. This message may contain information which are strictly confidential, urgent and protected by professional secrecy. It is then strictly prohibited, unless expressly authorized, any use, disclosure, copying or distribution of the content of this communication. If you have received this communication in error, please notify us immediately and then delete it from your system. In any case, considering the means of transmission, we do not undertake any liability with respect to the secrecy and confidentiality of the information contained in this e-mail and in its attachments. |
Gary W9TD
Paolo Garbin IV3BVK
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