#276

Building upon the lessons in videos #274 and #275, this video describes how to design a 2-element L-Network to create an impedance match to the desired system impedance using series and shunt (parallel) inductors and capacitors. The design process is described, and then actual matching results are measured using a Smith Chart on a VNA. PDF of the show notes:
www.qsl.net/w2a...
Previous Smith Chart videos:
#274: Basics of Smith Chart - Impedance and Admittance:
• #274: Smith Chart Basi...
#275: VSWR and Transmission Line Effects:
• #275: Smith Chart: Z, ...

[@rodericksibelius8472]

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.

[@davidcohen5938]

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.

[@hankhamner3671]

Very gifted man !

[@ottoomen5076]

I agree.

[@ashishderhgawen]

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.

[@johnthompson5034]

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.

[@denelson83]

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.

[@CuriouslyWatching]

You've rescued my semester with your videos. I am forever grateful to you. Thank you so so much

[@w2aew]

You're welcome! Please share my videos/channel with your classmates and professors. Do you mind telling me what school you're attending?

[@sraiken]

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!

[@maxk4324]

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 :)

[@PixelSchnitzel]

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 . . .

[@johnwest7993]

This is EXACTLY what I wanted to know, and now I know it. And in under 11 minutes. That was wonderfully clear. Thank you.

[@George-gz5zm]

Brilliant series on practical applications of the Smith chart. Better than university.

[@acestudioscouk-Ace-G0ACE]

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!

[@boonedockjourneyman7979]

I am amazed. Someone got the whole thing right in less than 20 minutes. Thank you.

[@wk2w]

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.

[@w2aew]

I"m glad that this series of videos helped to shed some light on the subject for you!

[@jeffomundson8761]

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...

[@user-wi2vl7wd7p]

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

[@Luzt.]

Enjoy? Sir, you a rock star! I'm afraid I'll have to watch all you videos ;-). Thank you and good luck.

[@alanwolke6253]

Thank you!

[@ernieschatz3783]

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.

[@idontseeit]

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?

[@w2aew]

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.

[@TheMorningbirdFoundation]

Thank you for a very clear and concise explanation and example.

[@derosram9333]

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.

[@DavePKW]

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.

[@smgvbest]

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.

[@josegermanparra6064]

Thanks again for a brilliant video! Using your video on the RF bridge and this I successfully tune my RandomWire antenna. Thanks!

[@southernexposure123]

Thank you. I've been looking for this information for days.

[@JackZimmermann]

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.

[@martinusher1]

Outstanding video. All this stuff is very obvious -- once its explained.

[@availablenowonwards]

Excellent... he simply does a 'copy paste' to your mind..!

[@ruvalcabagonzalezgerardo6316]

De verdad disfruto aprender con tus vídeos Haces que temas aparentemente complicados luzcan tal cual son Muchas gracias y saludos desde México 🇲🇽

[@apostolosgeorgiadis]

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?

[@abrahamkennedy3016]

you are a magician, you are a magician. you saved me in midterm.

[@shidharthoroy4402]

Your videos are great to follow! And the touch you give with the practical approach really helps along the way. Nice!

[@vonzigle]

The best instructional video I’ve seen on the Smith chart-thanks!

[@Cptnbond]

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!

[@Nobody-ld7mk]

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 !

[@shabeesatsangi]

I wish you were my teacher. i would have been at some good places designing some crazy stuff by now

[@leonardpeters3266]

Thank you for this. Greatly appreciated.

[@danielzdanowicz6899]

Wow! Awesome! I NOW understand Smith Charts a bit better! Thanks.

[@soajpg]

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...

[@siamakdadras3825]

Very informative and comprehensive video on impedance matching of a network. Thanks a million!

[@rlamb51]

Great Smithchart video series. I will invariably play through them often

[@MichaelLloyd]

Outstanding! I've needed this series for years. Smith Chart sales probably spiked when you released this video :o)

[@garethm5kvk802]

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.

[@twong689]

The video says a lot about impedance matching. Excellent!

[@Scuba_Bro]

Really great practical explanation of the topic. Wish I had more videos like this when I started grad school. Thanks for sharing the knowledge!

[@bblod4896]

Great explanation. You should be an instructor. Thanks.

[@tohopes]

Absolutely great demonstration, Alan.

[@zoolkhan]

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.

[@philipyoung9002]

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.

[@stefanosmakris5641]

Thank you for explaining with such clarity !

[@gustavomatos7428]

Your videos are a fantastic supplement material for transmission lines courses!

[@diy-projects]

thank you * 1000. best video out there. this really helps me during my fields and waves class at college

[@octavmandru9219]

It is indeed magical how wonderful theory works. Thanks Alan

[@Andreasonline3]

you are a bloody legend

[@DarkNemesis25]

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

[@rcberry]

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!

[@michaellove7912]

your videos are always helpful. thanks a bunch

[@user-yr3qk1bx3w]

I appreciate your good explanation.

[@manishbarnwal9342]

Really helpful videos to understand practical implementation.. Thanks..!!

[@trollshavesouls]

Great video! Helped me understand these concepts I’m learning in school! Thanks!

[@sabahhadhood603]

Excellent lecture.Thank you so so much.

[@TheRadioShop]

As always Alan very nice presentation. Thanks for doing these tutorials.

[@johnwoodcock5090]

Very nice. I prefer clockwise/counter-clockwise for adding reactances.

[@supyrow]

Alan you outdid yourself yet again, talk to you soon!

[@volkerblock]

"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.

[@alfredocrn]

Awesome videos!!! keep making them. Very clear, concise and to the point!

[@JimNicholsMotorManiaGarage]

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

[@grantfullen9559]

GREAT video. Thanks for taking the time to make and share these videos

[@dus777]

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.

[@patrickohara9901]

Great job Alan! It would be nice to see how to match over a bandwidth rather than a single frequency.

[@w2aew]

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.

[@ornithopterindia]

👍Thank you sir.

[@tutortobey2139]

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!

[@w2aew]

Thank you - that error was noted a while back, and the downloadable PDF notes have been corrected.

[@ericthielking262]

This could be used to help predict settings for a transmatch, if one knows the antenna impeadance.

[@CH_Pechiar]

Excelente video como siempre! Gracias.

[@CuriousMarc]

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?

[@w2aew]

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).

[@tcarney57]

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

[@bunman2353]

you are a legend!

[@PelDaddy]

Great series. Thank you for all your hard work.

[@bloodedge]

Nice, i can finally understand and user Smith Chart. Thanks you.

[@EvgeniX.]

nice and detailed video! wonder what's the cons and pros of LC vs LL in this case?

[@TheGmr140]

Smith charts, I use online calculator or simple equation coded up in excel or matlab. Good to see this using microstrip traces

[@reedschrichte800]

Beautiful 🙂

[@mariofachinsky5639]

Super instructive and clear!!! thanks for sharing! 73 de LU2AW

[@tr3kn3rd]

Thank you for making this video

[@nuwanatthanayake]

Thank you Sir.Great work.

[@buffplums]

This is fabtantsitic given me the confidence to do some expirembtation

[@DavidGillooly]

Nice explanation and thanks for the mnemonics!

[@CodeJeffo]

@w2aew Alan, I would love if you could make a video about the complex impedance curve. Some practical applications. I believe there should be a way to do something like complex impedance fitting to equivalent circuit. Another topic would be how to do impedance matching to a range of frequencies. I can't find much information about this nor anyone covering this topic. Maybe it's an old art already forgotten. Thank you very much for any hints where one can find more information about this.

[@jonboro2000]

Can you do a video explaining conjugate matching? I haven't seen a good one on youtube explaining why, when, how. Just "this is the math of conjugate matching."

[@indigoskywalker]

Excellent video Alan, always wondered what these charts were called and what they represented

[@californiakayaker]

Very good groundwork theory . I'm trying to tell my friends that the VNA (NanoVNA) will remove a ton of fuzzy logic when trying to match something. The DYNAMIC NATURE of these smith charts when shown on a VNA is the secret sauce. I have a special smith chart labeled "RADIO TRANSMISSION LINE CALCULATOR" with instructions on the back , probably rather old, seems to only have what might be resistance circles. On the left side it is labeled on the top Positive reactance component , on left on bottom below resistance line it says negative reactance component. Around the outside of the primary circle it says Angle of Reflective Coefficient in Degrees. But, the unusual thing about my plastic smith chart is what I'm ceiling the primary chart is "mounted" on top of another plastic piece, and it has labeled numbers (ON THE OUTSIDE) , and near ZERO it says with arrows pointing to left "wavelengths toward load" and on the right of Zero it says "Wavelengths toward Generator". The two pieces of plastic can be rotated. It has a piece on top of everything , a straight plastic piece, which is labled on the outside on left "voltage or current" and on right "attenuation /dissipation reflection" and is pinned on the center of the entire chart. I've heard it called a Transmission Line Slide Rule. If I knew how to use it I would make a video, but at this time I'm studying from a beginners level. I think the theory was produced by Bell Telephone Laboratories. Manufactured by The Emeloid Company in N.J.

[@alaricsnellpym]

If anybody wants to play with this in simulation in their browser, I made a Javascript simulator for T-network impedance matchers with Smith-chart visualisation of the impedance at each stage - it's here: love.warhead.org.uk/~alaric/junk/impedance-matcher.html Take a look at the source if you want to know how it works, it's fairly readable, and improvements are welcome! The T network is really just two series-C L networks back to back with a common inductor, so that it can be adjusted to bring an impedance from anywhere on the chart to the origin in one step, so it's popular with ham radio folks who are attempting to match a rusty bucket to their 50 ohm transceiver.

[@43SunSon]

One important question, why there is power reflection if impedance are NOT matched ?

[@w2aew]

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.

[@DonDegidio]

Hi Alan, Great demonstration. Deserves more than a thumbs up. :-) 73 WB3BJU

[@tezlallc2900]

Really well done!

[@vk5fe943]

Thanks, Alan.

[@t1d100]

If you wanted to preserve the position of the windings on the DIY inductor, you might spray them with Rust-Oleum/American Accents/2x Ultra Cover/For Plastics. Care would be needed to keep the distance such that the air pressure does not move the windings. But, this method seems less likely to disturb the windings, than applying a glue. Just thinking...

[@elpechos]

Thanks very much. I love this.

[@ninadam]

Thanks for the awesome video! I was wondering will you ever do a video on wide band matching?

[@pratwurschtgulasch6662]

if the impedance is perfectly matched at the frequency of interest, that also implies that the frequency of interest is not being filtered out correct? nobody ever talks about the fact that there are technically an infinite number of matching solutions and depending on which you pick it is going to do some filtering. i know you touched on this subject very briefly, the way i see it is that impedance matching and filtering are basically the same thing and should be thought of as such.