Re: Odd readings using app.
FIRST ATTACHMENT: With an 'average' RT of 15 dB, I doubt much RF is getting to whatever is at the far end of the coax! The vast majority of the data indicates lossy coax. The coax is pretty lossy!!! You might have a real antenna at the other end that wants to ring at roughly 450 to 455 MHz. But with that much loss, not much RF will reach this 'maybe' antenna. Most of the data is due to lossy coax. SECOND ATTACHMENT: Really can't make much sense of this. Everything appears to be in milliohms. I don't know?? THIRD ATTACHMENT (Smith Chart): Again, lots of loss. Nearly all the data is within the 2:1 circle which indicates nothing but coax cable loss. It shows multiple real-axis crossings near center (50-ohms), but I seriously doubt much RF is reaching whatever is connected. Lots of loss! FOURTH ATTACHMENT: Again, all resistance indications illustrate a lot of loss with all values between 20 and 100-ohms. This is all due to cable loss. FIFTH ATTACHMENT: I would presume the horizontal assembly of plates that all the coaxial runs cross is copper and intended for lightning/discharge remediation. I'm not addressing the sheet of plywood at the top. This is NOT a proper installation for that purpose!!!! What's more, the 'ground' wire is too haphazardly routed and too small of a gauge to be of much good other than to serve as a return for small, low-frequency energy. CONCLUSION: I don't know how long the coax runs are, but I'd suggest replacing them all. All your plots show is loss in the cabling! The mostly <2:1 SWR across your measurement bandwidth is all due to coax loss. There is far too much loss indicted by all your measurements. This time: 1) have someone familiar with RF install them and use good cable and 2) Have someone familiat with proper return current (from close-by lightning strikes) do the 'grounding' side of the installation. You're right. It's a mess......... Dave - W?LEV On Tue, Oct 27, 2020 at 5:32 PM ERNEST AEC-RADIO <aecradio1@...> wrote: Okay, I saved each image, 1 through 4.
THese should now paint a better picture of what I am dealing with.
I have no clue which antenna these readings are for, and that is one tiny
problem I doubt I will get an answer to.
The cable runs are excessive, well over 150 feet, and at least two
transitions in between.
The entire cable plant is a horrid nightmare!
The cables were hung/run/strung up by someone that had NO RF experience!
One walk through would incite laughter and hysteria...how any signal can
reach any of those antennas, MUST be a miracle!
I will have to take one pic just to prove the mess I have to deal with.
In fact, I am going to try doing that now.
-- *Dave - W?LEV* *Just Let Darwin Work*
|
Re: Measuring characteristic impedance of a stripline with a nanoVNA-H
On Tue, Oct 27, 2020 at 04:59 PM, Erik Kaashoek wrote: I know, but I like to have a method that works for "any" impedance/length and
"any" frequency combination Look at how a transmission line transforms a load impedance: The NanoVNA measurement gives you Zin = Rs + j*Xs, the impedance seen at the input of the transmission line. You know that the line is terminated with ZL = 50 ohms (at least that's what I think to see from your data). You have to solve this equation for beta and for Z0, the impedance of the line. You might wonder how you can solve one equation for two unknowns. But note that (neglecting losses) Z0 and beta are real, while your measurement gives you a complex Zin. I.e., in reality you have to equations, one for Rs and one for Zs. Also note that the equation becomes simpler if you can terminate your line with an approximate open (ZL = ¡Þ) or short (ZL = 0). Regards Christian
|
Re: Odd readings using app.
Okay, I saved each image, 1 through 4.
THese should now paint a better picture of what I am dealing with.
I have no clue which antenna these readings are for, and that is one tiny problem I doubt I will get an answer to.
The cable runs are excessive, well over 150 feet, and at least two transitions in between.
The entire cable plant is a horrid nightmare!
The cables were hung/run/strung up by someone that had NO RF experience!
One walk through would incite laughter and hysteria...how any signal can reach any of those antennas, MUST be a miracle!
I will have to take one pic just to prove the mess I have to deal with.
In fact, I am going to try doing that now.
|
Re: Odd readings using app.
Just do a screen capture, or "Print Screen", paste that into an image editor like Irfanview, and go from there. Dave - W?LEV On Tue, Oct 27, 2020 at 5:09 PM ERNEST AEC-RADIO <aecradio1@...> wrote: Well, the saved files did not attach as I expected, and the only means to
view, is copy them to Nano-VNA-Saver app.
Clearly, I did something wrong, I apologize. First time using the
application.
-- *Dave - W?LEV* *Just Let Darwin Work*
|
Re: Odd readings using app.
Well, the saved files did not attach as I expected, and the only means to view, is copy them to Nano-VNA-Saver app.
Clearly, I did something wrong, I apologize. First time using the application.
|
Greetings all:
A funny thing happened on the way to...........
At my work, we have a moderate selection of antrennas, but the issue is, nobody ran the cabling that identifies those antennas, or the bands they are operating in!
I have also found out that someone began cutting cables on the roof, and also failed to properly mark those antennas left unscathed.
What I am connected to, I have no clue, except to scan them with the Nano VNA, which shows some truly wild readings I have submitted for your amusement.
Simple naming, Alpha, and Alpha-1
I am using Nano-Saver for this
I just hope they display in the manner expected.
Please, be gentle...there are real Gremlins working here!
|
Here attached is a short brief on simple Z matching.
Alan
|
Re: Measuring characteristic impedance of a stripline with a nanoVNA-H
On Tue, Oct 27, 2020 at 08:58 AM, Dr. David Kirkby, Kirkby Microwave Ltd wrote:
Is it really stripline, and not microstrip?
Good point. It will be a coplanar waveguide with ground or microstrip lines with signal side ground plane (see: ) -- NanoVNA Wiki: /g/nanovna-users/wiki/homeNanoVNA Files: /g/nanovna-users/filesErik, PD0EK
|
Re: Measuring characteristic impedance of a stripline with a nanoVNA-H
I know, but I like to have a method that works for "any" impedance/length and "any" frequency combination This because the impedance is frequency dependent and I can not modify the length or target impedance And I want to be able to "probe" any stripline on the PCB by isolating it, connect it to the VNA at one side and put a 50ohm resistor at the other side Maybe too ambitious? -- NanoVNA Wiki: /g/nanovna-users/wiki/homeNanoVNA Files: /g/nanovna-users/filesErik, PD0EK
|
Re: Measuring characteristic impedance of a stripline with a nanoVNA-H
On Tue, 27 Oct 2020 at 15:24, Erik Kaashoek <erik@...> wrote: I'm trying to measure the (frequency dependent) characteristic impedance
of a 3cm stripline using a nanoVNA-H
Is it really stripline, and not microstrip? See difference at Dave
|
Re: Measuring characteristic impedance of a stripline with a nanoVNA-H
Erik,
try the 1/8 lambda method?
Arie Kleingeld
Op 27-10-2020 om 16:24 schreef Erik Kaashoek:
toggle quoted message
Show quoted text
I'm trying to measure the (frequency dependent) characteristic impedance of a 3cm stripline using a nanoVNA-H
Attached the measurement using nanoVNA-App.
Using RFsim99 I calculated that a 3cm stripline with impedance of 65ohm and a phase velocity of 1.25e+8m/s gave the same S11
How can I calculate from the data shown in nanoVNA-App to the characteristic impedance of 65ohm? Would that be of 1GHz (50 + 85)/2 (the center of the impedance circle?) is 67ohm?
So using some points (one below, one at and one above the frequency of interest?) on the impedance circle, should it be possible to calculate the stripline impedance for any frequency?
|
Measuring characteristic impedance of a stripline with a nanoVNA-H
I'm trying to measure the (frequency dependent) characteristic impedance of a 3cm stripline using a nanoVNA-H Attached the measurement using nanoVNA-App. Using RFsim99 I calculated that a 3cm stripline with impedance of 65ohm and a phase velocity of 1.25e+8m/s gave the same S11 How can I calculate from the data shown in nanoVNA-App to the characteristic impedance of 65ohm? Would that be of 1GHz (50 + 85)/2 (the center of the impedance circle?) is 67ohm? So using some points (one below, one at and one above the frequency of interest?) on the impedance circle, should it be possible to calculate the stripline impedance for any frequency? -- NanoVNA Wiki: /g/nanovna-users/wiki/homeNanoVNA Files: /g/nanovna-users/filesErik, PD0EK
|
Re: Nanovna-saver not recognizing SAA-2N
Ah, my version of saver was too old.? Updated and everything's working
fine.? Sorry for the noise and for not checking the obvious. (Thanks
)
toggle quoted message
Show quoted text
On 10/22/20, Toad Laurence via groups.io <g7psz@...> wrote: Well, I have many variants of the V2N (original uncased, but now with 3.2¡±
screen, ¡°Black and Gold¡± from Hugen and a V2N; all use the same basic v2-2
board architecture and should respond identically to the Nanosaver program.
I have been playing with it this afternoon after wrestling all morning with
SH**hub trying to download it, loading more dlls etc, generally going round
in circles and cursing under my breath at anyone who came into the room..
All my vnaV2s are recognised without problems on Com10, on my Win 7
Panasonic Toughbook laptop.
BUT the latter two vnas (Black and Gold and V2N) have the Japanese software
loaded, and it crashes Nanovna. A bit of a bummer as I rather like the
Japanise versions. My original V2 (same board and uses same firmware as V2N,
apart from the screen driver) works fine on Saver, Its human interface
leaves something to be desired (ie clunky by my standards but ok if you are
a professional nerd). Interestingly it could drive my V2 up to 5.4Ghz,
although despite recalibrating in Saver, it gave a fairly poor performance
above 4ghz.
Try a rescan of ports and click on any possble channels displayed in the box
and then make sure the Cyress driver is installed. I found the driver
installer on the same SH**hub page as the Nanosaver program.
Hope this helps.
Steve L
|
What is the difference between the curves in "Real/Imaginary" vs "R+jX (¦¸)" Charts - in NanoVNA Saver and NanoVNA 2_2 ?
What do they represent, as they usually have resonance on different frequencies?
Simen Tobiassen
|
Re: Nanovna-saver not recognizing SAA-2N
Well, I have many variants of the V2N...
Thanks Steve L, after much searching and going on wild goose chases, I finally figured out how to get into the Windows 8 device manager (Windows is not my native language.) It shows I indeed have the Cypress driver installed and in use for the V2. I installed QT as well, and it communicates with the V2 just fine so I'm pretty confident it is not an issue with the device. Perhaps I'll ask about this on the NanoVNA-V2 group. K On 10/22/20, Toad Laurence via groups.io <g7psz@...> wrote: Well, I have many variants of the V2N (original uncased, but now with 3.2¡±
screen, ¡°Black and Gold¡± from Hugen and a V2N; all use the same basic v2-2
board architecture and should respond identically to the Nanosaver program.
I have been playing with it this afternoon after wrestling all morning with
SH**hub trying to download it, loading more dlls etc, generally going round
in circles and cursing under my breath at anyone who came into the room..
All my vnaV2s are recognised without problems on Com10, on my Win 7
Panasonic Toughbook laptop.
BUT the latter two vnas (Black and Gold and V2N) have the Japanese software
loaded, and it crashes Nanovna. A bit of a bummer as I rather like the
Japanise versions. My original V2 (same board and uses same firmware as V2N,
apart from the screen driver) works fine on Saver, Its human interface
leaves something to be desired (ie clunky by my standards but ok if you are
a professional nerd). Interestingly it could drive my V2 up to 5.4Ghz,
although despite recalibrating in Saver, it gave a fairly poor performance
above 4ghz.
Try a rescan of ports and click on any possble channels displayed in the box
and then make sure the Cyress driver is installed. I found the driver
installer on the same SH**hub page as the Nanosaver program.
Hope this helps.
Steve L
|
Re: File /Antenna Analyzers Oct 24.pdf uploaded
#file-notice
Hello Barry, a lot of work you did to collect all these slides together and also a good presentation but too long for 1 hour. First you schould remove slide 16, because everything is said in slide 17 and presenting 16 before 17 will be confusing. Depending on your audience I think not to focus on too much theory but more practice as you do in your presentation. But when you must shorten your presentation you schould concentrate on only a few examples. One thing is to mention: Don?t focus on |Z|= 50 ohm in order to find best match on an antenna. That is wrong. You can achive |Z| = 50 ohms with R = 0 and X = 50 ohms also. But that represents a VSWR = infinity and no match at all! You should change that slides to show either the reflection factor in SmithChart, in frequency dependence or the VSWR. The last I think is best for radio amateurs, because it?s familiar to them. P.S. Nearly all VNAs use complex voltages to calculate S-parameters and reflection factors! Good luck in presentation 73, Guenter, DK5DN Am 25.10.2020 um 14:54 schrieb [email protected] Notification:
The following files have been uploaded to the Files area of the [email protected] group.
* /Antenna Analyzers Oct 24.pdf
</g/nanovna-users/files/Antenna Analyzers Oct
24.pdf>
*By:* Barry Feierman
*Description:*
I am working on a PPT presentation of the NANO VNA for local ham radio clubs, so am including my draft here for anyone to comment. This is posted here as a PDF file. TU for suggestions or corrections de Barry k3eui amateur radio call Phila area
|
Re: Using the NANO VNA to analyze antennas pdf file
Sounds like you will modify your presentation. Could you list the modified version? I'll look at it to improve my knowledge.
Jim
toggle quoted message
Show quoted text
At 06:57 AM 10/25/2020, Barry Feierman wrote: Hello Nano VNA users
I am working on a Power Point presentation of the Nano VNA as an antenna analyzer for local ham radio clubs.
|
Re: Using the NANO VNA to analyze antennas pdf file
Sounds like you will modify your presentation. Could you list the modified version? I'll look at it to improve my knowledge.
Jim
toggle quoted message
Show quoted text
At 06:57 AM 10/25/2020, Barry Feierman wrote: Hello Nano VNA users
I am working on a Power Point presentation of the Nano VNA as an antenna analyzer for local ham radio clubs.
|
Re: File /Antenna Analyzers Oct 24.pdf uploaded
#file-notice
Looks good. When you do get your presentation finished, it would be good to post it here as a .ppt with your talk notes attached. Then it could be available to all to use without needing to interpret some of the slides.
BruceN / K4TQL
--
*"To invent, you need a good imagination and a pile of junk"* -- Thomas Alva Edison (1847-1931)
|
Note, the Voltage Time Responses are exact, they are on top of each other and as well the currents are exact, as they are 240 mA...equally peak to peak . The I DC offset does not contribute any error in the response identity. Hence at the input ports, the responses are identical.
|
Dr. David Kirkby, Kirkby Microwave Ltd
Arie Kleingeld PA3A
schweppe