I took a Microwave Electronics Technician Class for 9 months at Microwave Training Institute taught by Alan Scott who owned the school in Mt. View, SILICON Valley, California, way back in 1985, and we had PhD's and practicing employed Electrical engineers as was our INSTRUCTORS from companies in the Silicon Valley designing MICROWAVE microstrip amplifiers and learned the use of the Smith Chart, Vector Network Analyzers, antennas, klystrons, magnetrons, etc... etc.. and many other unique subjects about the history and current state of the art of Microwave Engineering. I am now retired and watching this VIDEO made me have great admiration and RESPECT that this SHORT video less than 12 minutes has given be QUICK REFRESHER COURSE of the the applied knowledge and practical computational skills that can be applied in the REAL WORLD of Design. THANK YOU for a WELL THOUGHT OUT Presentation, SIR!, You deserve a MILLION SUBSCRIBERS FOR THIS! ~ Retired Engineering Technician.
There are instructors and there are teachers. You Alan are a gifted teacher, and you make the world a better place. Your ability to convey knowledge and understanding is truly a gift. Please keep it up.
I just designed an L match network using a Smith chart. Seeing the impedance move to the center seemed like magic. This is such a powerful tool. Your video is excellent. Can't thank you enough.
As a Radio Amateur (in more than one sense) this is the first time I've seen such a straightforward and practical explanation of impedance matching using a Smith Chart. No doubt these days there are ways of computing the values of components required but this method is just so satisfying and helps gain an understanding of what is actually involved in the process.
Very impressive. I wish I had seen this about 10 years during an antenna design and testing project. I did all you did but much more trial and error. At least I had a VNA and a good supply of passive components. One thing I learned is: RF system design is all about impedance matching!
I spent a considerable amount of time poring through Caron's Impedance Matching book, but never quite understood it as well as I did after watching this short video. Seeing the initial problem with a complex load impedance, the calculations, the Smith chart plots, and the immediate results on the VNA made all the difference in the world. There is enough information in these videos to work through any matching problem. This Smith Chart series is invaluable. So glad you were willing to devote time to making the videos. I imagine the prep time to create these was very substantial. Thank you once again, Alan.
Really well and clearly explained. You have a great gift for teaching. Your calm way of talking the student through, works really well for me. Thank-you!
Thank you a thousand times! The light has clicked on and I finally get it. Now to sit down with my VNA and do some hands-on to really sink the lesson in . . .
I study mechanical engineering, so you can imagine I am starting from scratch when it comes to RF circuitry. Yours is the first video out of SOOOOOOOOOOOOOOOOOOOOOOO many that I have watched about impedance matching that actually helped me understand the a practical approach to designing matching networks without getting bogged down with a textbook's worth of electrical engineering terms that a mech such as myself has no schooling in. Thank you so much for your hard work, and looking forward to watching more of your stuff :)
Thank you for putting this series together! You have clarified working with the smith chart, a subject I never really understood completely. It is really helpful to watch you work through an example. You are an Elmer to many...
This stuff is captivating to me. The graphical representation makes it so much easier to stay 'pointed in the right direction' when you are solving problems related to this.
I really enjoy this presentation. I come back and watch it ever so often just to refresh. Such an eloquent job. Thank you so much for all the fine work that you do.
incredible video. two things that would be great to elaborate on, you mentioned you CAN do it with two caps or two inductors but you say you dont want to, i dont think you ever mentioned why you wouldn't want to if you could. also, it would be nice to know what specific component and spec for those components would be key to look out for, when searching for inductors i see many notes on the components Q value and q frequency, self resonant frequency and dc resistance, all of which im scratching my head at. incredible video once again helped so much
Hey there, I know this is an older video but your teaching methodology is brilliant. Clear, encouraging, patient, deliberate, etc. You ever thought about writing an RF textbook?
Wow, that was great. the RF and Smith Charts are new to me and I've had a major problem understanding them. while I won't say things are crystal clear this certainly moved me in that direction. Love your teaching style very much.
Hey, this was SO helpful. So glad I found it! But, quick question, at 6:44, your Zload I think is a little off. It looks like you drew it along -j, not along -.51j. I'm confused, is that on puporse?
It was a typo on my handwritten normalized impedance. It should read 0.66 - j1.02. The PDF copy of the notes has this corrected. See page 5 of the PDF: www.qsl.net/w2aew/youtube/Smith_Chart_L-Network.pdf
Your capacity in delivering such well-structured and detailed tutorials, covering both the theoretical and experimental aspects is truly amazing. We are really grateful. Would you consider making a video on demonstrating and measuring the characteristic impedance of a transmission line and/or coax cable and its dependence on frequency?
Wow, as a german electrical engineering student I enjoy your perfect practical-orientated Videos. Would be great to have a Video about RF-Oscillator design, especially good quality VCOs with low harmonics for QRP projects.
I'll probably sound like a parrot, but your videos always keeps me amazed! Deep into RF now, and I'm actually thinking of getting a HAM license thanks to you. I find that I go back to your videos as reference again and again. If you're ever in Sweden, I'll buy you a beer.
I've only just found this channel, Alan, and I'm very glad I did. I was looking for some videos to refresh my 40+ EE education on Smith Charts and came across it. As others have said on here, learning about Smith Charts at university or to pass Ham exams tends to be mainly theoretical, though I did design a couple of fixtures for early ham antennas, but your approach has the benefits of being theoretically sound and very engaging. I will be looking for others and have subscribed.
Great stuff! Gonna look up more of your videos on Smith Charts! Do you have a more in depth Back to Basics video on why impedance matching is so important and the theory behind it? Could not find anything
Fantastic channel, really enjoy your clear and instructive style of presentations. I do have an electrical engineering exam, but boy I wished my teachers have been as good as you!
Fantastic series of crystal clear Smith chart videos (I’m binge watching). So now all of the power of the transmitter goes into the nicely matched line, but I suppose there is no miracle, it still does not all go to your mismatched load after the L adapter at the end. Is this correct? The extra power not going into the load is then dissipated by the matching network components I suppose? Being returned to ground by the inductor?
power can only be dissipated by resistance (line resistance, antenna/structure resistance, resistance in the tuner components, and radiation resistance). Thus, the bulk of it is indeed going to the radiation resistance (thus being radiated).
you are wonderful man. you found the truth in this world, you helped many people. may you find the truth in the afterworld, thats the least advice/help i can give to you in return...
Alan, very nice. I just purchased a NanoVNA. They are only $80.00 at Amazon and look pretty accurate for ham use. Check them out. Every ham can afford a VNA now. Amazing!
That was awesome! I could never find any information on how to build a matching network. Haha now I know why no one knows... It's math!! This was very informative and really something I've searched for many times. Thank you for the time you put into these videos. I'm a fan and new subscriber! 73, ke0eyh
I understand the schematic diagrams and what they mean and how they work but where I'm confused is to how to apply this theoretical knowledge to an actual antenna system. Do you have any videos or books that you could recommend of how to actually attach a parallel inductor or capacitor to an antenna or it series inductor or resistor to an antenna or combinations thereof would appreciate any recommendations that you have
Question: If you only have a Smith Chart with resistance circles for impedance, and you're Z_L is outside the 1+jX circle, can I simply move along the resistance circle until I reach the 1 + jB circle, find the inverted Y_L, and then move along the 1+jB circle to the center of the smith Chart? I find it slightly confusing when you have a series jX and then a shunt jB moving from Z_L to Z_in Oh, and one more thing. Do you have a link to somewhere we can find a Smith Chart with both impedance and admittance resistance circles? I have "The Complete Smith Chart" by Black Magic Design, but it's not so complete!
Does the Smith Chart have anything in common with a Nyquist plot? I sort of understand the basics of a nyquist plot but only use a bode plot in practical applications.
I watched videos of yours then practiced impedance matching for my 2.4Ghz antenna with my liteVNA (50Khz - 6Ghz), and I failed. It's hard to find the right components with small values, and the moving point on the smith chart was strange. Any tips for high-frequency antennas? 2.4Ghz is very common in life, hope there are some tutorials for 2.4Ghz.
Dear Alan, thanku so much for this wonderful demonstration. I am new to RF. I would like to ask you some doubts. You showed impedance matching for a single frequency(single point). How will we do impedance matching for a band of frequencies? Say I want to connect an antenna to a power amplifier board which operates for frequencies from 100 -200 MHz. Output impedance of my board is 50 ohm and I want to design a matching network to connect this amplifier output to an antenna ( impedance is not 50 ohms). What are the parameters that help me choose which configuration should i use? ( single LC section or multiple lc section, Lowpass or band pass). Like in a filter design we specify parameters like passband frequency, stop band frequency, passband stop band attenuation, how much variation we can afford in passband and stop band, with these paramaters we choose filter order and type of filter. Like this, which are the parameters that influence a matching circuit design. Can you suggest me any reference ( article or video)?
This is very nice and clear. However, I know not much about RF stuff, and I'm wondering under what circumstances you need such an impedance matching network, given that your calculations are aimed at a single frequency. Is this device only useful if you have, say, a transmitter connected to an aerial via a transmission line, and where you will only transmit at 14.2 MHz? If so, that seems rather restrictive to me. Or is this network useful over a wider bandwidth, but with less effect?
Impedance matching networks are often needed in RF circuits in order to obtain maximum power transfer. Some loads/antennae are only resonant at certain frequencies, necessitating the need for impedance matching circuits. These matching circuit typically operate well over a certain bandwidth or frequency range - depending on the design of the network.
Thanks, Alan. It's never been clear to me why transformers--in particular, Ruthroff 1:4 transmission-line types--are used in place of simpler L-networks when matching, say, 50 ohm IF amps to each end of a crystal filter. I think I understand why a transmission-line transformer is preferred over a conventional one, but why does one see almost no use of L-networks in that application? For use in an IF chain, impedance matching doesn't need to be broadband, and with an L-network the match can be fine tuned and not a fixed ratio. --Todd K7TFC
Quick comment, At around the 6:30 mark you have Z_l = 0.66-j0.51 but it should be Z_l ~0.66-1j since 51/50~1. This is also where you put your starting point on the smith chart. Good video though!
"Where were you when I was in school 30 years ago?? Excellent job! Keep the channel going. There is so much cool stuff to learn!!" Ha, 50 years ago and now I understand it. Age 75.
Maybe in future videos. That's one of the downsides of an L-network. The Q of the tuned circuit is pre-determined by the Z0 and load impedance. Other tuned circuit types (PI and T, and others) allow you to adjust for Q (bandwidth) somewhat.
I have a question that's troubling me for a long time about your SMA connectors, don't they also shift your smith chart? You can't "calibrate" them so how do you do to "remove" their effect and only observe what you are plugging?
The amount that the SMA connectors will rotate the impedance on the smith chart is really a function of frequency. If you feel they're adding too much after calibration, you can apply a port extension (called electrical length on the NanoVNA) to "move" the reference plane to the end of the connector. I have a video on this...
Why is it that adding inductor or capacitor doesn’t give me the movement along the circles like in theory and what you showed? I’m matching a 2.4ghz antenna fed by cpwg or microstrip line but the load doesn’t go where I want. I’m also using 0402 smd components that have fairly high SRFs around 3ghz.
Several things will cause this. You would have to have a calibration performed *directly* at the point where you're installing the matching components, thus establishing the measurement plane at this point. If this isn't done, then the transmission line leading to this point will cause the impedance to rotate around the chart (as well as any components you add). You may want to review my video that shows the transmission line effects. Also, at these frequencies (2.4GHz, etc.), components are far from ideal, even if their SRF is >>2.4GHz, so they won't necessarily follow the theory of an ideal component.
Please help me understand the following issue. I "get" that you have matched everything outside of the signal source to the ideal 50-ohm output impedance of the signal source. But the energy is not all going into the antenna. You are dissipating energy through the capacitor and inductor of your pad. So how does the pad help get power from the signal source into the antenna? Seems to me all you achieve is to get the power all the way down the coax with fewer reflected energy... but the energy doesn't all go into the antenna. Obviously, I'm missing something. Just cannot figure out what it is. Or do those extra pad components act as a tank and the energy simply "swishes" back and forth?
Reactive components like capacitors and inductors do not dissipate power, because the voltage across them and the current thru them are out of phase. Ideally, they are lossless - although in reality they have a "little" loss. So, in a sense, the power is recirculated - "swishing" back and forth.
Maximum power transfer only occurs when the load impedance matches the source impedance. Think about the extremes: A shorted load dissipates no power, and an open load dissipates no power. Thus the energy delivered down the transmission line is reflected back to the source.
Fantastic video.....A tough topic. Looking to create a little diy pcb for matching some stuff up to 2.485GHz....Was gonna use 1/2 oz cu (easier to cut with exacto). Most likely will work with 0.031" FR4. Do you recommend building this with single or double sided Cu?
Thank you for this very helpfull video. Is there a way to use Smith Chart (or other method) for matching to complex impedance instead of charateristic impedance? (I'm new to this all) I want to compensate for reflective impedance in transformer like setup.
Great explanation. I learn and understand a lot thank to you, master. However, I think there is a mistake in your paper @6:20 Zload = 33 - j 51 but when you normalize it should be ZL = 0.66 - j 1.02 ? Am I wrong ? Cheers from France :)
You are correct. I had plotted the correct point, but wrote the wrong point. I found this error earlier and corrected the PDF notes pages that are available here: www.qsl.net/w2aew//youtube/Smith_Chart_L-Network.pdf
You always have the cool toys! That LCR meter is an awesome tool! And, which software are you using that produces the smith chart through the device your using? De kd5smf
Hi, Thanks for another great video. I'm wondering is there way to match load to multiple freq? For example match antenna to GSM modem, that use multiple freq bands?
Outstanding! A key part in allowing a transmitter's power to make it out the antenna! Question: After you determine the component values for a chosen network, what is the process/calculation to ensure that the network will handle the transmitters output power?
If you use a tool like SimSmith, you can have it tell you the voltage and current that appears across and thru the reactive component do you can size them appropriately.
If for example you were designing an oscillator using an opamp. Would you only need to match the output impedance of the opamp to the resonant network. Because the input impedance to the opamp is very high?
Low power circuits like op amp oscillators, etc. don't need impedance matching - since you aren't generally concerned about maximizing *power* transfer, and you don't have transmission line effects, reflections, etc.
This at the base of an antenna, instead of at the antenna, would reduce SWR across the transmission line between the transmitter and antenna, right? It always makes sense to place these things as close as possible to the antenna?
Is it always going to be possible to balance a load to a source impedance? I'd like to get an idea on any limitations this chart has and if there's going to be scenarios where the impedance mismatch is too far apart to properly balance. I've been working toward a big loop at UHFs and everytime I find the inductive reactance plot lands all the way on the far far right near the real impedance axis and the values for components I've been finding have been infeasible ie. 228 attofarads. These videos have been extremely helpful, you're a better teacher than many I've had at my university.
Hello Alan, This is a great tutorial, with a unique approach I have not seen before, thank you for sharing! According to "RF Microelectronics" book, by Behzad Razavi, shunt element facing ZL can only be chosen when Zin < ZL. In the case of the chose example in this tutorial, RL(33 Ohm) < Rin(50 Ohm), which according to Razavi, should follow shunt at the input and series at the load. Please, comment on the above and how do you explain your reasoning. Regards, Eugene
Razavi's statement is correct, but is not the only way to go. The Ying-Yang diagrams give a more complete picture of which networks can be used. Often times there are two or three different options you can choose.
I took a Microwave Electronics Technician Class for 9 months at Microwave Training Institute taught by Alan Scott who owned the school in Mt. View, SILICON Valley, California, way back in 1985, and we had PhD's and practicing employed Electrical engineers as was our INSTRUCTORS from companies in the Silicon Valley designing MICROWAVE microstrip amplifiers and learned the use of the Smith Chart, Vector Network Analyzers, antennas, klystrons, magnetrons, etc... etc.. and many other unique subjects about the history and current state of the art of Microwave Engineering. I am now retired and watching this VIDEO made me have great admiration and RESPECT that this SHORT video less than 12 minutes has given be QUICK REFRESHER COURSE of the the applied knowledge and practical computational skills that can be applied in the REAL WORLD of Design. THANK YOU for a WELL THOUGHT OUT Presentation, SIR!, You deserve a MILLION SUBSCRIBERS FOR THIS! ~ Retired Engineering Technician.
There are instructors and there are teachers. You Alan are a gifted teacher, and you make the world a better place. Your ability to convey knowledge and understanding is truly a gift. Please keep it up.
Very gifted man !
I agree.
I just designed an L match network using a Smith chart. Seeing the impedance move to the center seemed like magic. This is such a powerful tool. Your video is excellent. Can't thank you enough.
You've rescued my semester with your videos. I am forever grateful to you. Thank you so so much
You're welcome! Please share my videos/channel with your classmates and professors. Do you mind telling me what school you're attending?
As a Radio Amateur (in more than one sense) this is the first time I've seen such a straightforward and practical explanation of impedance matching using a Smith Chart. No doubt these days there are ways of computing the values of components required but this method is just so satisfying and helps gain an understanding of what is actually involved in the process.
Very impressive. I wish I had seen this about 10 years during an antenna design and testing project. I did all you did but much more trial and error. At least I had a VNA and a good supply of passive components. One thing I learned is: RF system design is all about impedance matching!
Ohm my goodness...
I think I am starting to understand Smith charts a lot more, giving me a lot more insight when it comes to impedance matching.
I spent a considerable amount of time poring through Caron's Impedance Matching book, but never quite understood it as well as I did after watching this short video. Seeing the initial problem with a complex load impedance, the calculations, the Smith chart plots, and the immediate results on the VNA made all the difference in the world. There is enough information in these videos to work through any matching problem. This Smith Chart series is invaluable. So glad you were willing to devote time to making the videos. I imagine the prep time to create these was very substantial. Thank you once again, Alan.
I"m glad that this series of videos helped to shed some light on the subject for you!
Really well and clearly explained. You have a great gift for teaching. Your calm way of talking the student through, works really well for me. Thank-you!
Thank you a thousand times! The light has clicked on and I finally get it. Now to sit down with my VNA and do some hands-on to really sink the lesson in . . .
I study mechanical engineering, so you can imagine I am starting from scratch when it comes to RF circuitry. Yours is the first video out of SOOOOOOOOOOOOOOOOOOOOOOO many that I have watched about impedance matching that actually helped me understand the a practical approach to designing matching networks without getting bogged down with a textbook's worth of electrical engineering terms that a mech such as myself has no schooling in. Thank you so much for your hard work, and looking forward to watching more of your stuff :)
This is EXACTLY what I wanted to know, and now I know it. And in under 11 minutes. That was wonderfully clear. Thank you.
Thank you for a very clear and concise explanation and example.
I am amazed. Someone got the whole thing right in less than 20 minutes. Thank you.
Brilliant series on practical applications of the Smith chart. Better than university.
Thank you for putting this series together! You have clarified working with the smith chart, a subject I never really understood completely. It is really helpful to watch you work through an example. You are an Elmer to many...
Thank you. I've been looking for this information for days.
This stuff is captivating to me. The graphical representation makes it so much easier to stay 'pointed in the right direction' when you are solving problems related to this.
Thank you so much for sharing your knowledge Alan! You are an excellent teacher!
Enjoy? Sir, you a rock star! I'm afraid I'll have to watch all you videos ;-). Thank you and good luck.
Thank you!
I really enjoy this presentation. I come back and watch it ever so often just to refresh. Such an eloquent job. Thank you so much for all the fine work that you do.
incredible video. two things that would be great to elaborate on, you mentioned you CAN do it with two caps or two inductors but you say you dont want to, i dont think you ever mentioned why you wouldn't want to if you could. also, it would be nice to know what specific component and spec for those components would be key to look out for, when searching for inductors i see many notes on the components Q value and q frequency, self resonant frequency and dc resistance, all of which im scratching my head at. incredible video once again helped so much
Hey there, I know this is an older video but your teaching methodology is brilliant. Clear, encouraging, patient, deliberate, etc. You ever thought about writing an RF textbook?
I've thought about it, and have even been asked about writing several times (RF, basic electronics, etc.), but just don't have the time.
Wow, that was great. the RF and Smith Charts are new to me and I've had a major problem understanding them. while I won't say things are crystal clear this certainly moved me in that direction. Love your teaching style very much.
Hey, this was SO helpful. So glad I found it!
But, quick question, at 6:44, your Zload I think is a little off. It looks like you drew it along -j, not along -.51j. I'm confused, is that on puporse?
It was a typo on my handwritten normalized impedance. It should read 0.66 - j1.02. The PDF copy of the notes has this corrected. See page 5 of the PDF: www.qsl.net/w2aew/youtube/Smith_Chart_L-Network.pdf
Your capacity in delivering such well-structured and detailed tutorials, covering both the theoretical and experimental aspects is truly amazing. We are really grateful. Would you consider making a video on demonstrating and measuring the characteristic impedance of a transmission line and/or coax cable and its dependence on frequency?
Your videos are great to follow! And the touch you give with the practical approach really helps along the way. Nice!
Wow, as a german electrical engineering student I enjoy your perfect practical-orientated Videos. Would be great to have a Video about RF-Oscillator design, especially good quality VCOs with low harmonics for QRP projects.
AEW's video tutorials keep the knot's off your head. This one helps put the L/C icing on the cake. "Crazy Good" Circa 1939" Wow !
I'll probably sound like a parrot, but your videos always keeps me amazed! Deep into RF now, and I'm actually thinking of getting a HAM license thanks to you. I find that I go back to your videos as reference again and again. If you're ever in Sweden, I'll buy you a beer.
The best instructional video I’ve seen on the Smith chart-thanks!
Excellent... he simply does a 'copy paste' to your mind..!
I didn't know about L circuit before i watch this video
But now, thanks to ur explanation, i understood
thanks for helping me :)
From south korea
I've only just found this channel, Alan, and I'm very glad I did. I was looking for some videos to refresh my 40+ EE education on Smith Charts and came across it.
As others have said on here, learning about Smith Charts at university or to pass Ham exams tends to be mainly theoretical, though I did design a couple of fixtures for early ham antennas, but your approach has the benefits of being theoretically sound and very engaging.
I will be looking for others and have subscribed.
Great stuff! Gonna look up more of your videos on Smith Charts! Do you have a more in depth Back to Basics video on why impedance matching is so important and the theory behind it? Could not find anything
De verdad disfruto aprender con tus vídeos
Haces que temas aparentemente complicados luzcan tal cual son
Muchas gracias y saludos desde México 🇲🇽
Fantastic channel, really enjoy your clear and instructive style of presentations. I do have an electrical engineering exam, but boy I wished my teachers have been as good as you!
you are a magician, you are a magician. you saved me in midterm.
Very informative and comprehensive video on impedance matching of a network. Thanks a million!
Outstanding! I've needed this series for years. Smith Chart sales probably spiked when you released this video :o)
Great Smithchart video series. I will invariably play through them often
Fantastic series of crystal clear Smith chart videos (I’m binge watching). So now all of the power of the transmitter goes into the nicely matched line, but I suppose there is no miracle, it still does not all go to your mismatched load after the L adapter at the end. Is this correct? The extra power not going into the load is then dissipated by the matching network components I suppose? Being returned to ground by the inductor?
power can only be dissipated by resistance (line resistance, antenna/structure resistance, resistance in the tuner components, and radiation resistance). Thus, the bulk of it is indeed going to the radiation resistance (thus being radiated).
The video says a lot about impedance matching. Excellent!
you are wonderful man. you found the truth in this world, you helped many people. may you find the truth in the afterworld, thats the least advice/help i can give to you in return...
Beautifully done! Love the presentation with actual hardware being used for me to get a feel of what's going on. Thumbs up, up , up.
Really great practical explanation of the topic. Wish I had more videos like this when I started grad school. Thanks for sharing the knowledge!
Absolutely great demonstration, Alan.
Thanks again for a brilliant video! Using your video on the RF bridge and this I successfully tune my RandomWire antenna. Thanks!
Outstanding video. All this stuff is very obvious -- once its explained.
Your videos are a fantastic supplement material for transmission lines courses!
It is indeed magical how wonderful theory works. Thanks Alan
greetings from Finland. i am very grateful for your teachings. i am a big fan and i hope you will never stop with your videos. 73 de oh8xat.
Alan, very nice. I just purchased a NanoVNA. They are only $80.00 at Amazon and look pretty accurate for ham use. Check them out. Every ham can afford a VNA now. Amazing!
Thank you for explaining with such clarity !
Great explanation. You should be an instructor.
Thanks.
Awesome videos!!! keep making them. Very clear, concise and to the point!
As always Alan very nice presentation. Thanks for doing these tutorials.
That was awesome! I could never find any information on how to build a matching network. Haha now I know why no one knows... It's math!! This was very informative and really something I've searched for many times. Thank you for the time you put into these videos. I'm a fan and new subscriber! 73, ke0eyh
nice and detailed video! wonder what's the cons and pros of LC vs LL in this case?
Alan you outdid yourself yet again, talk to you soon!
I understand the schematic diagrams and what they mean and how they work but where I'm confused is to how to apply this theoretical knowledge to an actual antenna system. Do you have any videos or books that you could recommend of how to actually attach a parallel inductor or capacitor to an antenna or it series inductor or resistor to an antenna or combinations thereof would appreciate any recommendations that you have
Question: If you only have a Smith Chart with resistance circles for impedance, and you're Z_L is outside the 1+jX circle, can I simply move along the resistance circle until I reach the 1 + jB circle, find the inverted Y_L, and then move along the 1+jB circle to the center of the smith Chart? I find it slightly confusing when you have a series jX and then a shunt jB moving from Z_L to Z_in
Oh, and one more thing. Do you have a link to somewhere we can find a Smith Chart with both impedance and admittance resistance circles? I have "The Complete Smith Chart" by Black Magic Design, but it's not so complete!
Does the Smith Chart have anything in common with a Nyquist plot? I sort of understand the basics of a nyquist plot but only use a bode plot in practical applications.
why do plasma machines use 2 capacitors for matching if their regime to match is low? 4:05
Great video! Helped me understand these concepts I’m learning in school! Thanks!
thank you * 1000. best video out there. this really helps me during my fields and waves class at college
Wow! Awesome! I NOW understand Smith Charts a bit better! Thanks.
GREAT video. Thanks for taking the time to make and share these videos
I watched videos of yours then practiced impedance matching for my 2.4Ghz antenna with my liteVNA (50Khz - 6Ghz), and I failed. It's hard to find the right components with small values, and the moving point on the smith chart was strange. Any tips for high-frequency antennas? 2.4Ghz is very common in life, hope there are some tutorials for 2.4Ghz.
Dear Alan, thanku so much for this wonderful demonstration. I am new to RF. I would like to ask you some doubts. You showed impedance matching for a single frequency(single point). How will we do impedance matching for a band of frequencies? Say I want to connect an antenna to a power amplifier board which operates for frequencies from 100 -200 MHz. Output impedance of my board is 50 ohm and I want to design a matching network to connect this amplifier output to an antenna ( impedance is not 50 ohms). What are the parameters that help me choose which configuration should i use? ( single LC section or multiple lc section, Lowpass or band pass).
Like in a filter design we specify parameters like passband frequency, stop band frequency, passband stop band attenuation, how much variation we can afford in passband and stop band, with these paramaters we choose filter order and type of filter.
Like this, which are the parameters that influence a matching circuit design. Can you suggest me any reference ( article or video)?
This is very nice and clear. However, I know not much about RF stuff, and I'm wondering under what circumstances you need such an impedance matching network, given that your calculations are aimed at a single frequency. Is this device only useful if you have, say, a transmitter connected to an aerial via a transmission line, and where you will only transmit at 14.2 MHz? If so, that seems rather restrictive to me. Or is this network useful over a wider bandwidth, but with less effect?
Impedance matching networks are often needed in RF circuits in order to obtain maximum power transfer. Some loads/antennae are only resonant at certain frequencies, necessitating the need for impedance matching circuits. These matching circuit typically operate well over a certain bandwidth or frequency range - depending on the design of the network.
Thanks, Alan. It's never been clear to me why transformers--in particular, Ruthroff 1:4 transmission-line types--are used in place of simpler L-networks when matching, say, 50 ohm IF amps to each end of a crystal filter. I think I understand why a transmission-line transformer is preferred over a conventional one, but why does one see almost no use of L-networks in that application? For use in an IF chain, impedance matching doesn't need to be broadband, and with an L-network the match can be fine tuned and not a fixed ratio. --Todd K7TFC
I just happen to be working on a project in the 20m ham band, and the load just happens to look similar. And, now I understand what to do and why.
Quick comment, At around the 6:30 mark you have Z_l = 0.66-j0.51 but it should be Z_l ~0.66-1j since 51/50~1. This is also where you put your starting point on the smith chart. Good video though!
Thank you - that error was noted a while back, and the downloadable PDF notes have been corrected.
"Where were you when I was in school 30 years ago?? Excellent job! Keep the channel going. There is so much cool stuff to learn!!" Ha, 50 years ago and now I understand it. Age 75.
Great job Alan! It would be nice to see how to match over a bandwidth rather than a single frequency.
Maybe in future videos. That's one of the downsides of an L-network. The Q of the tuned circuit is pre-determined by the Z0 and load impedance. Other tuned circuit types (PI and T, and others) allow you to adjust for Q (bandwidth) somewhat.
I wish you were my teacher. i would have been at some good places designing some crazy stuff by now
I have a question that's troubling me for a long time about your SMA connectors, don't they also shift your smith chart? You can't "calibrate" them so how do you do to "remove" their effect and only observe what you are plugging?
The amount that the SMA connectors will rotate the impedance on the smith chart is really a function of frequency. If you feel they're adding too much after calibration, you can apply a port extension (called electrical length on the NanoVNA) to "move" the reference plane to the end of the connector. I have a video on this...
Why is it that adding inductor or capacitor doesn’t give me the movement along the circles like in theory and what you showed? I’m matching a 2.4ghz antenna fed by cpwg or microstrip line but the load doesn’t go where I want. I’m also using 0402 smd components that have fairly high SRFs around 3ghz.
Several things will cause this. You would have to have a calibration performed *directly* at the point where you're installing the matching components, thus establishing the measurement plane at this point. If this isn't done, then the transmission line leading to this point will cause the impedance to rotate around the chart (as well as any components you add). You may want to review my video that shows the transmission line effects. Also, at these frequencies (2.4GHz, etc.), components are far from ideal, even if their SRF is >>2.4GHz, so they won't necessarily follow the theory of an ideal component.
Please help me understand the following issue. I "get" that you have matched everything outside of the signal source to the ideal 50-ohm output impedance of the signal source. But the energy is not all going into the antenna. You are dissipating energy through the capacitor and inductor of your pad. So how does the pad help get power from the signal source into the antenna? Seems to me all you achieve is to get the power all the way down the coax with fewer reflected energy... but the energy doesn't all go into the antenna.
Obviously, I'm missing something. Just cannot figure out what it is. Or do those extra pad components act as a tank and the energy simply "swishes" back and forth?
Reactive components like capacitors and inductors do not dissipate power, because the voltage across them and the current thru them are out of phase. Ideally, they are lossless - although in reality they have a "little" loss. So, in a sense, the power is recirculated - "swishing" back and forth.
Thank you.
Excellent video Alan, always wondered what these charts were called and what they represented
One important question, why there is power reflection if impedance are NOT matched ?
Maximum power transfer only occurs when the load impedance matches the source impedance. Think about the extremes: A shorted load dissipates no power, and an open load dissipates no power. Thus the energy delivered down the transmission line is reflected back to the source.
Fantastic video.....A tough topic. Looking to create a little diy pcb for matching some stuff up to 2.485GHz....Was gonna use 1/2 oz cu (easier to cut with exacto). Most likely will work with 0.031" FR4. Do you recommend building this with single or double sided Cu?
Double sided so you can get better shielding and 50 ohm lines.
A big thumbs up as usual Allan, do you have any tutorials on how to figure out the operating range of an unknown toroid with tests and some math?
Not yet...
Thank you for this. Greatly appreciated.
Thank you for this very helpfull video.
Is there a way to use Smith Chart (or other method) for matching to complex impedance instead of charateristic impedance? (I'm new to this all)
I want to compensate for reflective impedance in transformer like setup.
Yes, the Smith Chart can be "normalized" to any desired impedance. I don't have any examples of doing this however.
@@w2aew Thank for the answer, now I know it's possible so I can look further into it.
Thanks for the awesome video! I was wondering will you ever do a video on wide band matching?
Great explanation. I learn and understand a lot thank to you, master.
However, I think there is a mistake in your paper @6:20
Zload = 33 - j 51 but when you normalize it should be ZL = 0.66 - j 1.02 ? Am I wrong ?
Cheers from France :)
You are correct. I had plotted the correct point, but wrote the wrong point. I found this error earlier and corrected the PDF notes pages that are available here:
www.qsl.net/w2aew//youtube/Smith_Chart_L-Network.pdf
Very nice. I prefer clockwise/counter-clockwise for adding reactances.
Nice, i can finally understand and user Smith Chart. Thanks you.
You always have the cool toys! That LCR meter is an awesome tool! And, which software are you using that produces the smith chart through the device your using? De kd5smf
your videos are always helpful. thanks a bunch
Hi, Thanks for another great video.
I'm wondering is there way to match load to multiple freq?
For example match antenna to GSM modem, that use multiple freq bands?
It is possible, but is most often done through the antenna design itself.
Thanks.
Outstanding! A key part in allowing a transmitter's power to make it out the antenna! Question: After you determine the component values for a chosen network, what is the process/calculation to ensure that the network will handle the transmitters output power?
If you use a tool like SimSmith, you can have it tell you the voltage and current that appears across and thru the reactive component do you can size them appropriately.
Thank you!
Great series. Thank you for all your hard work.
Nice explanation and thanks for the mnemonics!
If for example you were designing an oscillator using an opamp. Would you only need to match the output impedance of the opamp to the resonant network. Because the input impedance to the opamp is very high?
Low power circuits like op amp oscillators, etc. don't need impedance matching - since you aren't generally concerned about maximizing *power* transfer, and you don't have transmission line effects, reflections, etc.
w2aew thanks Alan
This at the base of an antenna, instead of at the antenna, would reduce SWR across the transmission line between the transmitter and antenna, right? It always makes sense to place these things as close as possible to the antenna?
Yes, always a good idea to place the matching network at the antenna - minimizes loss on the feedline.
Is it always going to be possible to balance a load to a source impedance? I'd like to get an idea on any limitations this chart has and if there's going to be scenarios where the impedance mismatch is too far apart to properly balance. I've been working toward a big loop at UHFs and everytime I find the inductive reactance plot lands all the way on the far far right near the real impedance axis and the values for components I've been finding have been infeasible ie. 228 attofarads. These videos have been extremely helpful, you're a better teacher than many I've had at my university.
Hello Alan,
This is a great tutorial, with a unique approach I have not seen before, thank you for sharing!
According to "RF Microelectronics" book, by Behzad Razavi, shunt element facing ZL can only be chosen when Zin < ZL. In the case of the chose example in this tutorial, RL(33 Ohm) < Rin(50 Ohm), which according to Razavi, should follow shunt at the input and series at the load. Please, comment on the above and how do you explain your reasoning.
Regards,
Eugene
Razavi's statement is correct, but is not the only way to go. The Ying-Yang diagrams give a more complete picture of which networks can be used. Often times there are two or three different options you can choose.