This video is the best and most comprehensible discussion of the Smith Chart that I've ever seen - an excellent demonstration, not only of theory but teaching ability. Thanks.
No doubt this is the best Tutorial on transmission line and antenna system measurements. The way you explained the correlation is superb and easy to follow. Thanks a lot. Missing the probe tip though 😊
I completely agree. The part , starting basically at 42:30 (I've also seen it in another video of his) was similar to starting a chainsaw in front of a cave man who had never seen one running. Wow ! Whats that noise ? What an eye opener !
@@michaelshreeve5192 If you want to do it on a paper chart you have to order the special smith charts paper with the blue lines. Its very hard to see for most older people, but not me as I still have one myopic eye ! My other eye had cataract surgery and is 20-20. That said, the Nano VNA just does this and its as if it knows where the conductance and admittance lines are supposed to be. I call it a "Dynamic" smith chart ! Do you do anything with "SIM SMITH" ?
Alan, Your video serves as another example of the idea that anyone can get a world class free education by simply watching good videos and examples like this one. Thanks for sharing! 73, N7KBC
When your video comes in everything stops here until I watch it. Another great one. You make a tremendous contribution to engineering education. Great job.
While restoring a Gates BC-1T AM xmitter, I came across this presentation. Could not have been more perfectly timed as I began the pi network rebuild and connection to my balanced doublet antenna. It demystified some RF challenges along the way and helped me enjoy a successful finish to my 800 lb (literally) project. In fact, your library of videos are a wonderful gift to the amateur radio community and anyone desiring to go a bit deeper into electronics. Thank you.
As an Electrical Engineer, and Ham Radio Operator, I have must say, this was one of the best videos I have seen on this subject. I wish it was available when I was taking my electromagnetism courses.
Thank you for this very instructive video! I was thinking that in the old days (1960s-1970s) we had publications like Popular Electronics that often made me think, and then I realized that channels like yours provide a similar experience today. Thank you!!
Hello Alan, I have watched approximately 60% of your videos. Soooo much information and so easy to understand the way you tell it. I am going to be joining the Ham Radio World thanks to you. Just wanted to thanks!
All your videos are superb. Your laid back, pleasant yet concise and undistracted presentation style is supremely easy to stay engaged with. This one in particular was/is extremely useful to me. It laid to rest some of the questions I've been unable to resolve from the many online sources that sometimes seem to offer conflicting and confusing information, dispelling much of the doubt I had about some concepts and correcting some misconceptions by lucidly explaining ideas with your self-assured and very credible explanations. In short, you are an outstanding teacher. Thank you so much.
To help with YT popularity algo I am commenting. I used to think I was smart and could capture quickly almost anything at a glance, but Smith charts repeatedly humiliated me and pretty much corrected me. They seemed bizarrely complicated but here you show the way. Thank you so much. You are an excellent teacher! Wonderful! The yin/yang charts at 40-42 minutes with circuits are truly special standouts in an extraordinarily clear teaching video. I love ALL your videos. They are all great examples of your clear-minded teaching excellence - but amongst your especially good videos - this one is even more especially good! TY 🙂
Excellent presentation. Just getting into this field (after trying to avoid it for years) to improve my DIY IoT sensors. Had seen a couple of other videos, but you brought it all together in a way that perfectly matched my poor understanding. I learned so much in just one hour!
This was outstanding ! I picked up Walt Maxwell's ( W2DU) book a few years back. He changed the way I think about and work with transmission lines and antennas forever .The only trouble I had with the book was putting his Smith charts to work. You have just made it so simple for me to understand. I guess I will have to dive back into the book now. Thanks and 73 !
Excellent practical explanation. Very neat to see how it all adds up. 20 years ago I had the Smith chart as part of the education for electronic engineer, but used a vector network analyser only in a few occasions. Never worked with Smith chart in this way. Very nice to be able to calculate your way to match the network in a few clear steps. Very interesting. I will watch this video at least one more time 🙂 Thank you for your effort! I have bought a nanoVNA H4 recently and will start to use it.
Agree with the comments - fantastic content - a must for amateur experimenters - aren't NanoVNAs just the best piece of cheap test equipment for the shack!! 73, Justin, VK7TW
It frightens me that I think I understood a fair bit of that! I'm not a amateur radio'er; I always feel like I'm getting on someone else's bus when I watch your radio-oriented vids. :) Nicely done. And the production values of this session... excellent. As much as I prefer Actual Humans, I guess there is an advantage to preparing a talk for online, in that you can scale it up to any size audience!
Well done! Rather than just saying, "match by attaching the complex conjugate of the impedance". So that's what is going on in my antenna tuner! And all the radio's matching networks. -K3JDD
Hi Alan Excellent stuff as always. I've been licensed since the early 70s doing quite a bit of construction and building. I have known that altering feedline length can change SWR but was at a loss to explain why. Your explanation struck me as basic and even embarassed me. Now I know why. For others that want to delve down deeper into this subject, and there is much more, Larry Benko W0QE has his own RUclips Website which deals with the subject. It references a Computer Program "SimSmith" that is a powerful tool itself. For those interested just put W0QE in the youtube search engine. But be forewarned this is a deep subject. Larry like Alan is a Degreed and Highly Experienced EE. His videos are not as easy to follow as Alan's.
Excellent. Might do one showing how multiple matching stages have wider bandwidth because they have lower Q, which on a Smith chart are arcs above and below Z = 0 and intersect R 0 and infinity.
What an incredible video Alan. Your teaching ability is amazing. Is there a particular NanoVNA that you would recommend? It seems that there are a number of them on the market. And just searching NanoVNA is very confusing. Thanks WB7DUO
Great video, Alan, as usual. Thanks very much. To close the loop on antenna matching networks, would you consider making a video talking about how to choose the right L and C components? I know inductors can be homemade, but how do I determine wire diameter, core material, number of turns, etc.? What types of capacitors are suitable? Cheers!
Great presentation - thank you so much! BTW, Smith charts are a powerful graphical way of solving the impedance matching problem, it would be interesting to learn more on analytical solutions to the matching problem. Most ATU:s sounds like a spanish castanets player on drugs when optimizing but surely there must be analytical solutions? If one turns the solution sought by the ATU into a two dimensional random walk optimization problem, I guess one would also be at risk of ending up in local minima?
The benefit to an L-network is that there is only 1 minima. A T or PI network have have multiple solutions. The downside is that you have to pick the right L network topology. There are analytical solutions, but they require a vector measurement, not just a reflected power measurement which is typical in auto tuners.
Long but informative video.some jargons are difficult to understand clubbing all at a time.but got the essence if video.i understood that adding coax does not effect vswr except the coax is part of Antenaa (knowing or unknowingly!) that is need to clarify further as it change impedance but not vswr!
I have an automatic tuner (LDG Z-817) that requires an antenna connection, a connection to the transceiver and a serial connection to the transceiver to function. I know I can use a NanoVNA to tune the antenna itself, but I'm not quite sure how I would break out the connection to see what exactly the tuner is doing or if it would even be possible since the transceiver goes into a PKT transmit mode so the tuner can figure out what to do. Not sure what that would even do to the NanoVNA or if it can even pass signal through the SMA ports. I suppose I could connect the NanoVNA to the antenna and adjust it as good as I can, connect the antenna to the tuner and have it do it's thing and then connect the NanoVNA to the tuner and note the change. Thoughts? Great video by the way. Took what appeared to be a difficult subject and made it very easy to understand.
Unfortunately, you can't "watch" what the tuner is doing since it needs the transmitter signal to do it's job. But, assuming the tuner holds its setting once tuned, you can disconnected the radio and connect the NanoVNA to see the result that the tuner came up with. You'll also be able to sweep over a frequency range to see how broad the tuned result is (i.e. how far can you tune the radio from the original tuned frequency and still have a decent SWR).
Hi Alan, thank you very much for the great explanation. Your videos are the real treasure! I have one doubt, and I would be grateful if you can help me to clarify. If we have an external antenna (for instance flex antenna) that is attached to the PCB via coaxial cable and u.fl connector, and the matching circuit is placed on the PCB (let’s say before u.fl connector, if it has sense), how to perform impedance measurement/find the right measurement plane? If we attach VNA at the matching circuit, should we also somehow include the length of the antenna coax cable (actually the distance from the matching circuit to the antenna) because, as you mention in the video, its length changes the way how the impedance is seen from the other side (rotating on constant VSWR circle)? I am a little confused about this. Thank you!
You would apply the concept of Port Extension. I have a video on this: ruclips.net/video/bEPUePy_buM/видео.html Adjusting the amount of delay or port extension can be done experimentally. You'd start (after calibrating at whatever point you can) by estimating how much you need to move the measurement plane from the calibration location. If it is possible to solder/attach a temporary short at the desired measurement plane, you can then use either the phase plot or the Smith chart and watch the result as you tweak the delay / port extension value until the phase plot goes flat (or the Smith chart goes to dot at 9 o'clock).
Thank you very much for those videos. I was trying to understand how to make a Pi matching network to design a PCB for one ESP32-S2 soc. It has an outuput impedance of 35ohm+0j and I need to match it to a 50ohm MIFA trace antenna at 2442MHz. I kow there are some web applications bit I would love to see a video about that using Smith Chart. Thank you very much.
The process of using a smith chart for designing an L-network for impedance matching starts at 39:00 in the video. Do you really need a Pi network where an L-network will do?
A quick search uncovered this: www.amazon.com/Smith-Chart-Graph-Paper-Electronics/dp/170265169X and www.amazon.com/Smith-Chart-Notebook-transmission-Electronics/dp/179862737X/
When I move antenna during measurement, the VNA display different SWR and impedance. And difference could be radical. So how do I determine which result is the correct one???
Antenna impedance can be greatly affected by their surroundings. So, if you move the antenna, the distance to ground and surrounding objects (even your body) will change, and this can affect the impedance of the antenna. So, the answer is *all* of the results are correctly showing you the impedance of the antenna in that particular position. It is best to measure an antenna in the location where it will be used.
@@w2aew Thanks for reply! However I am designing tourist antenna, which means no fix to particular position. Seems need to carry NanoVNA along my trips to find proper impedance at each stop-station.
Great content. Forgive the stupid question, but I am analyzing / tuning a cobweb antenna. Feed line is about 100' from transceiver. Do I connect NanoVNA right were my transceiver is and calibrate with the short / open / load at the antenna feed point (100' away)? I originally calibrated the NanoVNA with the shot / open / load right on the Nano itself, then did analysis with 10' of RG8U right at / near the antenna. Now with feedline attached to antenna and NanoVNA at transeiver end, things look totally different. I am not sure what to trust. So back to my original question I guess: "Do I connect NanoVNA right were my transceiver is and calibrate with the short / open / load at the antenna feed point (100' away)?"
In the end - what is most important is "what is the transmitter seeing". Replace the transmitter with the NanoVNA, calibrated at the VNA ports, will then show you what the TX sees by establishing the calibration plane at the TX end of the cable.
I recently obtained a NANOVNA H4 and I have this question for you. I wanted to take a 9:1 unun and look at the secondary winding which should be 450 ohms. I've only seen videos where they are looking at the primary side (50 ohm feedline side) which is easy enough to accomplish. For looking at the secondary, 450 ohm antenna feed point on the unun, I reset the H4 to read 450 ohms on the Smith Chart 1.0 system impedance point to normalize it. The H4 now displays "PORT-Z: 50 -> 450 Ohms". The results look very good. Is this the proper way to have accomplished this, or should I have left it at 50 ohms and divided 450/50 and located that point on the 9.0 horizontal prime access line?
I believe what you did is correct. I haven't played with that feature yet. But, if you terminate the 50 ohm side into 50 ohms, and the smith chart is shown (near) bullseye center on the S11 on the 450 ohm side, then I say you are doing it right.
Is it best to probe the antenna with little to no transmission line? If you wanted to figure out the impedance for a multiband antenna, how can you best figure out the matching circuit?
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This video is the best and most comprehensible discussion of the Smith Chart that I've ever seen - an excellent demonstration, not only of theory but teaching ability. Thanks.
No doubt this is the best Tutorial on transmission line and antenna system measurements. The way you explained the correlation is superb and easy to follow. Thanks a lot. Missing the probe tip though 😊
Been doing digital/analogue electronics for 35+ years. Just getting into RF and your videos are nothing short of pure GOLD.
I completely agree. The part , starting basically at 42:30 (I've also seen it in another video of his) was similar to starting a chainsaw in front of a cave man who had never seen one running. Wow ! Whats that noise ? What an eye opener !
@@michaelshreeve5192 If you want to do it on a paper chart you have to order the special smith charts paper with the blue lines. Its very hard to see for most older people, but not me as I still have one myopic eye ! My other eye had cataract surgery and is 20-20. That said, the Nano VNA just does this and its as if it knows where the conductance and admittance lines are supposed to be. I call it a "Dynamic" smith chart ! Do you do anything with "SIM SMITH" ?
Absolutely!!
Brilliant Thankyou
Alan, Your video serves as another example of the idea that anyone can get a world class free education by simply watching good videos and examples like this one. Thanks for sharing! 73, N7KBC
When your video comes in everything stops here until I watch it. Another great one. You make a tremendous contribution to engineering education. Great job.
You just filled in the blanks that were keeping me from understanding a Smith Chart and use my VNA. Thank you!!! 73 NE5U
Alan as always you have provide pure education. Thank you as posted before pure GOLD (Simon Baxter). I love it. 73
A valuable collection of information ! Thank you so much for this video.
Sir, this is absolutely marvellous. Your are a superb teacher.
Jawaid.(Member of Pakistan Amateur Radio Society)
While restoring a Gates BC-1T AM xmitter, I came across this presentation. Could not have been more perfectly timed as I began the pi network rebuild and connection to my balanced doublet antenna. It demystified some RF challenges along the way and helped me enjoy a successful finish to my 800 lb (literally) project. In fact, your library of videos are a wonderful gift to the amateur radio community and anyone desiring to go a bit deeper into electronics. Thank you.
I'm following along with the NanoVNA hooked up to an antenna. Great stuff Alan. Thanks, Scott W0KU.
Excellent information, thank you so much for producing these videos.
My Smith Chart training was decades ago so I wanted a refresher. This is excellent. Thanks!
As an Electrical Engineer, and Ham Radio Operator, I have must say, this was one of the best videos I have seen on this subject. I wish it was available when I was taking my electromagnetism courses.
Hi, the example at the end was the key to bringing it all together. An excellent presentation. Thank you for all of your videos!
Thank you for this very instructive video! I was thinking that in the old days (1960s-1970s) we had publications like Popular Electronics that often made me think, and then I realized that channels like yours provide a similar experience today. Thank you!!
This is one good lecture and lecturer . Appreciate it.
Hello Alan, I have watched approximately 60% of your videos. Soooo much information and so easy to understand the way you tell it. I am going to be joining the Ham Radio World thanks to you. Just wanted to thanks!
This has got to be your best videos great jobs. I’m surprised you didn’t mention the Sim Smith software
Thanks Alan. I'm still trying to understand all of this, however this chart is a HUGE help through visualization. Keep up the great videos. 73's.
All your videos are superb. Your laid back, pleasant yet concise and undistracted presentation style is supremely easy to stay engaged with. This one in particular was/is extremely useful to me. It laid to rest some of the questions I've been unable to resolve from the many online sources that sometimes seem to offer conflicting and confusing information, dispelling much of the doubt I had about some concepts and correcting some misconceptions by lucidly explaining ideas with your self-assured and very credible explanations.
In short, you are an outstanding teacher. Thank you so much.
Thank you, that is very kind of you to say. I'm very happy to hear that you got a lot out of this video.
To help with YT popularity algo I am commenting. I used to think I was smart and could capture quickly almost anything at a glance, but Smith charts repeatedly humiliated me and pretty much corrected me. They seemed bizarrely complicated but here you show the way. Thank you so much. You are an excellent teacher! Wonderful! The yin/yang charts at 40-42 minutes with circuits are truly special standouts in an extraordinarily clear teaching video. I love ALL your videos. They are all great examples of your clear-minded teaching excellence - but amongst your especially good videos - this one is even more especially good! TY 🙂
This is the charm of good engineer, make things easier to understand. Cheers Alan!
Thank-you Alan. very informative great video. I really like your teaching method.
Like the previous commenter said, this is pure gold. Love your videos!
Excellent presentation. Just getting into this field (after trying to avoid it for years) to improve my DIY IoT sensors. Had seen a couple of other videos, but you brought it all together in a way that perfectly matched my poor understanding. I learned so much in just one hour!
This was outstanding ! I picked up Walt Maxwell's ( W2DU) book a few years back. He changed the way I think about and work with transmission lines and antennas forever .The only trouble I had with the book was putting his Smith charts to work. You have just made it so simple for me to understand. I guess I will have to dive back into the book now. Thanks and 73 !
Excellent practical explanation. Very neat to see how it all adds up. 20 years ago I had the Smith chart as part of the education for electronic engineer, but used a vector network analyser only in a few occasions. Never worked with Smith chart in this way. Very nice to be able to calculate your way to match the network in a few clear steps. Very interesting. I will watch this video at least one more time 🙂 Thank you for your effort! I have bought a nanoVNA H4 recently and will start to use it.
Fantastic presentation! Great mix of fundamental and practical info presented in a manner that even I can understand. Well done!
Thank you. You are such a great teacher- understanding both the mathematical and practical side of Smith charts really helps.
Agree with the comments - fantastic content - a must for amateur experimenters - aren't NanoVNAs just the best piece of cheap test equipment for the shack!! 73, Justin, VK7TW
It frightens me that I think I understood a fair bit of that! I'm not a amateur radio'er; I always feel like I'm getting on someone else's bus when I watch your radio-oriented vids. :) Nicely done.
And the production values of this session... excellent. As much as I prefer Actual Humans, I guess there is an advantage to preparing a talk for online, in that you can scale it up to any size audience!
I enjoyed it too. A mountain of valuable info. Thanks
I agree Your videos are Pure gold Always needed for a refresher course with practice applications.
Thanks much for sharing this. I know how to use my VNA however I'm not great at explaining it to others. You've done a great job here!
Well done! Rather than just saying, "match by attaching the complex conjugate of the impedance". So that's what is going on in my antenna tuner! And all the radio's matching networks. -K3JDD
Great job explaining antenna tuning!
Hi Alan Excellent stuff as always. I've been licensed since the early 70s doing quite a bit of construction and building. I have known that altering feedline length can change SWR but was at a loss to explain why. Your explanation struck me as basic and even embarassed me. Now I know why. For others that want to delve down deeper into this subject, and there is much more, Larry Benko W0QE has his own RUclips Website which deals with the subject. It references a Computer Program "SimSmith" that is a powerful tool itself. For those interested just put W0QE in the youtube search engine. But be forewarned this is a deep subject. Larry like Alan is a Degreed and Highly Experienced EE. His videos are not as easy to follow as Alan's.
John Boy Utah, if I had a teacher like you early on I would be an EE rather than a AAS in EE!😎🇺🇸👍🏻
Thank you. Learn a lot from your videos. My teachers look like idiots now.
Always a great presentation...
Excellent beginner video. Bravo.
Sir, you have the gift! Please use it more for good of humanity! Make more videos like this!
Many thanks ,and 73's.
I had this question last night for the 2-meter round table. Google is scary sometimes, but this was great.
Great video, very informative!
Another excellent video. Thanks! 73 de Jon
Excellent. Might do one showing how multiple matching stages have wider bandwidth because they have lower Q, which on a Smith chart are arcs above and below Z = 0 and intersect R 0 and infinity.
Brilliant, thanks so much for a wonderfully clear explanation, really helpful. Mortimer R-T G4BSK
Great video
What an incredible video Alan. Your teaching ability is amazing. Is there a particular NanoVNA that you would recommend? It seems that there are a number of them on the market. And just searching NanoVNA is very confusing. Thanks WB7DUO
It's tough to recommend one, there are a lot, and a lot of different sources. I mainly use a NanoVNA-H4 and a NanoVNA V2plus4.
great lesson!
Very nice!
Brilliant.
Great video, Alan, as usual. Thanks very much. To close the loop on antenna matching networks, would you consider making a video talking about how to choose the right L and C components? I know inductors can be homemade, but how do I determine wire diameter, core material, number of turns, etc.? What types of capacitors are suitable? Cheers!
Comment for the RUclips popularity algorithm. Excellent video though.
Thank you! Concise and clear!
Great presentation - thank you so much! BTW, Smith charts are a powerful graphical way of solving the impedance matching problem, it would be interesting to learn more on analytical solutions to the matching problem. Most ATU:s sounds like a spanish castanets player on drugs when optimizing but surely there must be analytical solutions? If one turns the solution sought by the ATU into a two dimensional random walk optimization problem, I guess one would also be at risk of ending up in local minima?
The benefit to an L-network is that there is only 1 minima. A T or PI network have have multiple solutions. The downside is that you have to pick the right L network topology. There are analytical solutions, but they require a vector measurement, not just a reflected power measurement which is typical in auto tuners.
Bringing It to life in 2D! (that's as many D's as my brain voltage can cope with). 73, M0YZT
Excellent compilation - KF6GG
Great video for the rest of us dummies(me)
Long but informative video.some jargons are difficult to understand clubbing all at a time.but got the essence if video.i understood that adding coax does not effect vswr except the coax is part of Antenaa (knowing or unknowingly!) that is need to clarify further as it change impedance but not vswr!
I have an automatic tuner (LDG Z-817) that requires an antenna connection, a connection to the transceiver and a serial connection to the transceiver to function. I know I can use a NanoVNA to tune the antenna itself, but I'm not quite sure how I would break out the connection to see what exactly the tuner is doing or if it would even be possible since the transceiver goes into a PKT transmit mode so the tuner can figure out what to do. Not sure what that would even do to the NanoVNA or if it can even pass signal through the SMA ports. I suppose I could connect the NanoVNA to the antenna and adjust it as good as I can, connect the antenna to the tuner and have it do it's thing and then connect the NanoVNA to the tuner and note the change. Thoughts? Great video by the way. Took what appeared to be a difficult subject and made it very easy to understand.
Unfortunately, you can't "watch" what the tuner is doing since it needs the transmitter signal to do it's job. But, assuming the tuner holds its setting once tuned, you can disconnected the radio and connect the NanoVNA to see the result that the tuner came up with. You'll also be able to sweep over a frequency range to see how broad the tuned result is (i.e. how far can you tune the radio from the original tuned frequency and still have a decent SWR).
I thought you were starting your own club? Lol. Where do I sign up?! Lol
How much do you charge to speak for a group?
I don't charge to speak for a radio club, of course.
Hi Alan, thank you very much for the great explanation. Your videos are the real treasure! I have one doubt, and I would be grateful if you can help me to clarify. If we have an external antenna (for instance flex antenna) that is attached to the PCB via coaxial cable and u.fl connector, and the matching circuit is placed on the PCB (let’s say before u.fl connector, if it has sense), how to perform impedance measurement/find the right measurement plane? If we attach VNA at the matching circuit, should we also somehow include the length of the antenna coax cable (actually the distance from the matching circuit to the antenna) because, as you mention in the video, its length changes the way how the impedance is seen from the other side (rotating on constant VSWR circle)? I am a little confused about this. Thank you!
You would apply the concept of Port Extension. I have a video on this: ruclips.net/video/bEPUePy_buM/видео.html
Adjusting the amount of delay or port extension can be done experimentally. You'd start (after calibrating at whatever point you can) by estimating how much you need to move the measurement plane from the calibration location. If it is possible to solder/attach a temporary short at the desired measurement plane, you can then use either the phase plot or the Smith chart and watch the result as you tweak the delay / port extension value until the phase plot goes flat (or the Smith chart goes to dot at 9 o'clock).
Do other visual people visual learners like me look at this and see the inside of a tube that bends to the right and gets smaller in the distance?
Thank you very much for those videos. I was trying to understand how to make a Pi matching network to design a PCB for one ESP32-S2 soc. It has an outuput impedance of 35ohm+0j and I need to match it to a 50ohm MIFA trace antenna at 2442MHz. I kow there are some web applications bit I would love to see a video about that using Smith Chart. Thank you very much.
The process of using a smith chart for designing an L-network for impedance matching starts at 39:00 in the video. Do you really need a Pi network where an L-network will do?
One like is not enough!
👍🙏👍
73! 88!
Hi I really appreciate your teaching style this was so helpful I was curious do you know if it's possible to get blank notepads of Smith charts
A quick search uncovered this: www.amazon.com/Smith-Chart-Graph-Paper-Electronics/dp/170265169X
and
www.amazon.com/Smith-Chart-Notebook-transmission-Electronics/dp/179862737X/
When I move antenna during measurement, the VNA display different SWR and impedance. And difference could be radical. So how do I determine which result is the correct one???
Antenna impedance can be greatly affected by their surroundings. So, if you move the antenna, the distance to ground and surrounding objects (even your body) will change, and this can affect the impedance of the antenna. So, the answer is *all* of the results are correctly showing you the impedance of the antenna in that particular position. It is best to measure an antenna in the location where it will be used.
@@w2aew Thanks for reply! However I am designing tourist antenna, which means no fix to particular position. Seems need to carry NanoVNA along my trips to find proper impedance at each stop-station.
@@sugarvenom2189 Very common with VHF/UHF antennas. You just have get them close and not sweat it.
Great content. Forgive the stupid question, but I am analyzing / tuning a cobweb antenna. Feed line is about 100' from transceiver. Do I connect NanoVNA right were my transceiver is and calibrate with the short / open / load at the antenna feed point (100' away)? I originally calibrated the NanoVNA with the shot / open / load right on the Nano itself, then did analysis with 10' of RG8U right at / near the antenna. Now with feedline attached to antenna and NanoVNA at transeiver end, things look totally different. I am not sure what to trust. So back to my original question I guess: "Do I connect NanoVNA right were my transceiver is and calibrate with the short / open / load at the antenna feed point (100' away)?"
In the end - what is most important is "what is the transmitter seeing". Replace the transmitter with the NanoVNA, calibrated at the VNA ports, will then show you what the TX sees by establishing the calibration plane at the TX end of the cable.
@@w2aew - Thanks! for closure, I found an issue with the remote antenna switch that was causing the difference!
🌟🌟🌟🌟🌟🌹
I recently obtained a NANOVNA H4 and I have this question for you.
I wanted to take a 9:1 unun and look at the secondary winding which should be 450 ohms. I've only seen videos where they are looking at the primary side (50 ohm feedline side) which is easy enough to accomplish.
For looking at the secondary, 450 ohm antenna feed point on the unun, I reset the H4 to read 450 ohms on the Smith Chart 1.0 system impedance point to normalize it. The H4 now displays "PORT-Z: 50 -> 450 Ohms". The results look very good. Is this the proper way to have accomplished this, or should I have left it at 50 ohms and divided 450/50 and located that point on the 9.0 horizontal prime access line?
I believe what you did is correct. I haven't played with that feature yet. But, if you terminate the 50 ohm side into 50 ohms, and the smith chart is shown (near) bullseye center on the S11 on the 450 ohm side, then I say you are doing it right.
@@w2aew Yes, I did terminate the primary feedline side with 50 ohms. Thanks for your reply. Your videos are extremely helpful to me.
Is it best to probe the antenna with little to no transmission line? If you wanted to figure out the impedance for a multiband antenna, how can you best figure out the matching circuit?
The important thing is to establish the calibration / measurement plane at the same point where you intend to apply the matching circuit.
👍👍73s