|
Here is my latest rendition of the pdf file: Nano VNA: An Antenna Stethoscope
After giving a few Zoom club talks on the Nano VNA, I've changed my approach a bit.
This is still a very basic look at how a VNA can be used as a "tool" in your antenna toolbox.
I hope it explains why impedance changes with feed line length and approaches resonance in a novel way.
Feedback is appreciated, both on and off this IO group.
de K3eui
Barry
West Chester PA
k3euibarry@...
|
Barry-
Very nice presentation on the basics of VNA analysis. Quite well done. I¡¯m sure you put in considerable time on it.
After doing a quick review of your slides there were only a couple items that I felt needed correction.
They both relate to your discussion of TDR measurements using a VNA. In slides # 9 and 19 you speak about pulses of RF being sent out. That would be correct for a conventional TDR, however the TDR plots generated by a VNA are created by applying a FFT to the steady state (not pulsed) reflected signal of the VNA. No electrical pulses are involved. The TDR function is based on the mathematical FFT.
The remainder of the slide set looked pretty good based on my quick reading.
Best Regards,
Ray
WB6TPU
toggle quoted message
Show quoted text
On Feb 23, 2021, at 6:33 PM, Barry Feierman <k3euibarry@...> wrote:
?Here is my latest rendition of the pdf file: Nano VNA: An Antenna Stethoscope
After giving a few Zoom club talks on the Nano VNA, I've changed my approach a bit.
This is still a very basic look at how a VNA can be used as a "tool" in your antenna toolbox.
I hope it explains why impedance changes with feed line length and approaches resonance in a novel way.
Feedback is appreciated, both on and off this IO group.
de K3eui
Barry
West Chester PA
k3euibarry@...
|
On Wed, Feb 24, 2021 at 03:28 AM, Barry Feierman wrote:
Nano VNA: An Antenna Stethoscope
I will add my appreciation to Roy's and to his comment about the slightly erroneous TDR explanation. There are a couple of items i would take up with you- The picture /display of attenuation versus frequency of the RG-8 is enlightening and you could add a comment that the regularity and smoothness of this graph is a direct indication of the qualities of the cable being sampled. The 'smoother' the better! There are some very nasty variants of Super-8, RG-8, or RG-8Mini type cables with markedly worse characteristics marketed around the world. I would choose another way of talking about dipole antennas than showing them without a balancing transformer (1:1 balun) at the centre feed point. As without a balun here one will always have a third element to the antenna i.e. the outside of the coax feeder cable and this extra element will modify all the impedances measured. As an antenna it still works with both horisontal and vertical radiation components but as a demonstration - I have serious doubts about the results. Peter
|
Berry -- this is a great bit of work. Lots of meat here and served up very well.
I read this multipule times and get a bit more into my thick skull each time.
Good job!
Don
Km4udx
|
You can also take your Resistive, Reactive, Complex Numbers and run them straight over to Sim Smith for some more fun. I wish we had these Nano's 30 years ago, it's positively amazing what bang for the buck is packed in to the NanoVna. I'm looking forward to design upgrades in the future as far as how it's packaged, would like to see the touch screen done away with for push buttons in a larger model.
|
Barry,
Thanks! Appreciate your hard work. Your explanations parted the clouds for me. Now I feel like I'm flying "VFR on top."
Bob, WA2DLL
|
This is high quality work. I also had reservations regarding the TDR explanation on the nanoVNA, which was well explained in another post.
I wish there was a bit more commentary to elaborate on the slides so we can hear what you¡¯re thinking when you present them. Perhaps doing up the slide presentation with audio commentary and posting to YouTube? I would very much like to view that.
--
VE6WGM
|
Barry K3EUI-
I appreciate your dedication to bring this effort to the group.
Obviously there is a Power Point version. You will be in demand when hamfests, return Shortly.
I encourage you to narrate a Power Point Presentation and place it on DVD for distribution at nominal cost to Clubs.
I spoke to the ARRL at a ARRL convention to promote such presentations that would be available like some sort of traveling virtual speaker.
Of course any Idea that takes the ARRL into the 21st century falls on deaf ears. But I would pay easily $20 for a copy that I could use at a club meeting. I am a member of 3 clubs, and trust me, without some sort of presentation such as this would be; those meetings are like watching paint drying. OK now we'll vote on the Treasures Report. All those in Favor?? Why even bring it up, unless the treasury is $0 and - I assure you there would be no Treasurer giving that report of ZERO funds.. Is it any reason, the next generation is not interested in ham clubs and meetings.
W?VFW is now going to alternating monthly meeting with an activity. March will be the 1st meeting since the China plague.
Larry W8LM
ARRL LIFE MEMBER - Licensed 55 years.
VFW post 3115 Amateur Radio Club, W?VFW -Wichita, KANSAS
Past President 2 terms- VE Team Leader 12 years - Training officer.
|
I like the idea but would suggest a USB drive instead of a DVD, as most laptops no longer have DVD drives and USB/thumb drives are quite inexpensive. From: Larry Macionski via groups.io<mailto:am_fm_radio@...> Sent: Wednesday, February 24, 2021 12:07 PM To: [email protected]<mailto: [email protected]> Subject: Re: [nanovna-users] Nano VNA: An Antenna Stethoscope ( pdf file latest edition de k3eu ) Barry K3EUI- I appreciate your dedication to bring this effort to the group. Obviously there is a Power Point version. You will be in demand when hamfests, return Shortly. I encourage you to narrate a Power Point Presentation and place it on DVD for distribution at nominal cost to Clubs. I spoke to the ARRL at a ARRL convention to promote such presentations that would be available like some sort of traveling virtual speaker. Of course any Idea that takes the ARRL into the 21st century falls on deaf ears. But I would pay easily $20 for a copy that I could use at a club meeting. I am a member of 3 clubs, and trust me, without some sort of presentation such as this would be; those meetings are like watching paint drying. OK now we'll vote on the Treasures Report. All those in Favor?? Why even bring it up, unless the treasury is $0 and - I assure you there would be no Treasurer giving that report of ZERO funds.. Is it any reason, the next generation is not interested in ham clubs and meetings. W?VFW is now going to alternating monthly meeting with an activity. March will be the 1st meeting since the China plague. Larry W8LM ARRL LIFE MEMBER - Licensed 55 years. VFW post 3115 Amateur Radio Club, W?VFW -Wichita, KANSAS Past President 2 terms- VE Team Leader 12 years - Training officer.
|
On 2/24/21 9:06 AM, Larry Macionski via groups.io wrote: Barry K3EUI-
I appreciate your dedication to bring this effort to the group.
Obviously there is a Power Point version. You will be in demand when hamfests, return Shortly.
I encourage you to narrate a Power Point Presentation and place it on DVD for distribution at nominal cost to Clubs.
I spoke to the ARRL at a ARRL convention to promote such presentations that would be available like some sort of traveling virtual speaker. Or post it on Youtube - No need for a DVD - someone can just download it and save it. I would suggest getting some help for this. Someone who is familiar with recording, editing, and synchronizing against the slides can do it in the blink of an eye, but hard to do by yourself.
|
All good ideas. Clubs are always looking for interesting programs.
Before Covid, our in-person club meeting would sometimes have a guest
speaker ¡°live¡± via Skype. We have a projector and some speakers to see and
hear the remote presenter, plus a camera on a tripod so the presenter can
see the room. We also have a mic on a long cord to pass around for
questions. For presenters, it¡¯s more work than a one time video, but it¡¯s
much more engaging than watching a video too.
Thank you to all who take their time to share what they have learned, no
matter how they make it happen!
toggle quoted message
Show quoted text
On Wed, Feb 24, 2021 at 12:41 PM Jim Lux <jim@...> wrote: On 2/24/21 9:06 AM, Larry Macionski via groups.io wrote:
Barry K3EUI-
I appreciate your dedication to bring this effort to the group.
Obviously there is a Power Point version. You will be in demand when hamfests, return Shortly.
I encourage you to narrate a Power Point Presentation and place it on DVD for distribution at nominal cost to Clubs.
I spoke to the ARRL at a ARRL convention to promote such presentations that would be available like some sort of traveling virtual speaker.
Or post it on Youtube - No need for a DVD - someone can just download it
and save it.
I would suggest getting some help for this. Someone who is familiar with
recording, editing, and synchronizing against the slides can do it in
the blink of an eye, but hard to do by yourself.
|
Thank you all for the great suggestions. I will modify (correct) the TDR slides. I was fascinated to watch the TDR "work" so well with some old coax I had in my shack, and just googled TDR to see if I could understand HOW it works.
Now.. I am at about a 9th grade understanding of this VNA technology, and I should know, since I taught 9th grade Physics for ten years at the end of teaching high school physics for 41 years (then university levels).
I've looked at the Nano VNA as something that I wanted to "tame" and have had fun learning, reading, playing, and even giving a few talks PPT to local clubs and some not so local to Philadelphia. With each presentation, I learn something new from the questions that pop up.
So no, I am not keen to "record" a presentation, although most of the clubs do record an hour or more for their own membership.
So I am still learning, and maybe in a few more months will feel more comfortable with my live presentations to go out on a YOUTUBE. Confidence grows with each presentation (try teaching 9th graders physics some time).
If you have a local club that is looking for an outside speaker, and can deal with this Nano VNA as a 9th grader, I'm your guy. I am not a professional RF engineer who has worked with VNAs his whole life.
If I can introduce someone to a new tool to have in their toolbox and learn as you go, that is enough for me.
Again, I do appreciate the pros explaining to me where a slide is misleading, or simply wrong.
I like the title now: The Nano VNA: An Antenna Stethoscope
(Like the EKG tells you something about the state of health of your heart if you know how to "read" it.
A VNA is one cool gadget
73
Barry k3eui
K3euibarry@...
|
Thanks, Barry, you did a good job on this. I was only wishing you had narrated or provided slides with your explanations as well, though.
I agree with Jim Lux, your PowerPoint should be on YouTube, so others can learn from you.
73
W7BPG
|
/almost/ all of it.....
Enjoy!
toggle quoted message
Show quoted text
On 2/24/21, Brian G. via groups.io <kc7dax@...> wrote: Thanks, Barry, you did a good job on this. I was only wishing you had
narrated or provided slides with your explanations as well, though.
I agree with Jim Lux, your PowerPoint should be on YouTube, so others can
learn from you.
73
W7BPG
--
jim fisher
Jedijf
AJ3DI
www.aj3di.com
HamshackHotline ext: 14423
"Do, or do not. There is no 'try.'"
-- Jedi Master Yoda
|
Very good Barry! Please let us know when you finally decide to release a YouTube recording of you narrating your slide presentation. I will be first in line to watch it!
Regards,
Gregg
--
VE6WGM
|
Ditto. Would love to hear the presentation accompanying the slides.
Jim
KQ9I
toggle quoted message
Show quoted text
On Wed, Feb 24, 2021, 9:10 PM Gregg Messenger <techgreg@...> wrote: Very good Barry! Please let us know when you finally decide to release a
YouTube recording of you narrating your slide presentation. I will be
first in line to watch it!
Regards,
Gregg
--
VE6WGM
|
Thank you so much for this tutorial! It is so good!!!
Terry NQ4Y
|
You can all thank AJ3DI Jim, my benefactor, for introducing me to this gadget called Nano NVA.
It forced me to take another look at many concepts: resistance, reactance, impedance, PHASE, and of course, how useful (or bewildering) a Smith Chart can be.
Of course, at my PhilMont Mobile Radio club presentation (over an hour) it was recorded, and although Jim missed the first couple of (very essential) slides, the talk can be viewed by anyone.
Each time I give this talk, I learn more about what the hurdles are. I find, as a teacher, we can "say the words and answer multiple choice exams without any REAL understanding".
My goal was to slow down enough for folks to see "resonance" and "phase" like a kid swinging on a swing and grampy (our feed line) giving the essential push to keep the current (kid) swinging.
A crude analogy, of course, for resonance in an antenna.
So have fun watching the video if you choose to spend an hour that way.
I usually prepare for many more slides than I actually show (rookie error).
Feedback is apprediated: K3euibarry at gmial.com
73
Barry
|
Hi Barry
Is the recording available to see somewhere? Do you have a link you could post?
Regards,
Gregg
--
VE6WGM
|
It was posted and recorded by AJ3DI back a few messages
This recording (about an hour long) missed the first few minutes, which I thought were essential to compare the Nano VNA to an Antenna Stethoscope and a Smith Chart to an EKG of your heart.
But it is what it is
73
Barry k3eui
K3euibarry at gmail.com
|
Barry K3EUI
Don - KM4UDX
Gregg Messenger VE6WGM
Larry Macionski
Jim Fisher AJ3DI