L-Network Impedance Matching

[@philhooper5769]

Electrical engineering student at Georgia Tech here. I couldn't stop laughing when you pulled out the RF circuit design book because I already had it on my desk!

[@Fatkuh]

And again a really well done and informative video - I especially like how your english gets better over the time of the video as you stop thinking about your words and start ranting on about what you like - RF Electronics. I really enjoy your channel! Keep up the good work!

[@BalticLab]

Thanks for your feedback. Yes, I can feel that transition myself. In my first video I re-shot entire scenes when I thought I said something wrong. Now I correct myself on-the-fly and just let it flow.

[@Starbuckin]

Thank you SO much for making this video, you may have indeed unlocked the secrets of impedance matching for me. After years of reading books I find that an instructor demonstrating the practical application of theory is what teaches me. I'm subbing you, please make more. -73 from KJ4JAE.

[@andrzejpl9897]

Pleasure to watch that video . RF is my love too. Thanks .

[@wk2w]

Appreciate your work. Very helpful and informative.

[@BalticLab]

Thank you so much. I intend to talk about it once I have some other topics covered and a solid subscriber core.

[@BalticLab]

Yes, you can build an antenna tuner with an L-Network. Traditionally, however, T-Networks are used. 5.8 GHz is really not that bad. Try it. And if you have difficulties, ask in forums for help. Amateur radio operators are also always good contacts.

[@markhenderson9069]

Great presentation, but i'm not quite understanding how he got the answer to the product over sum impedance problem @ 7:00 minutes-on. I got 221 ohms for the answer here. Where does he get the 75 ohms - j263 for the answer here? What is he doing? Can someone help me here? Thanks.

[@BalticLab]

Hey Mark, check out my text-blog article on the subject: baltic-lab.com/2013/04/l-network-impedance-matching/

[@ysvsny7]

Thanks. Best explanation

[@BalticLab]

Glad it was helpful!

[@DragonFlyy123]

Thanks for the very nice video!

[@BalticLab]

Glad I could help you!

[@wk2w]

Remarkably well explained. I was wondering if you could discuss the approach if the load impedance was complex, not a pure resistance. And, is there any chance you would be discussing Smith charts in the future? Thanks

[@cosimonisi5016]

many thanks for your video. very easy to understand. this was to calculate when the antenna has a high impedance (LC) can you also make a video to calculate when it is in low impedance (CL)? 73 dl3mim

[@senakawijayakoon]

Thank you very much about your useful video. I have a project to make a my own RF amplifier using a transistor. Then I need to make matching network for input and output of transistor. Please could you advice me whether you have a video lesson for such a project or suitable reference for that. Thank you

[@jlpeng9036]

this video is a very clear-explain! many thanks, bud=)

[@jfernandmy]

Hi! Great video, very interesting topic, I have always wondered whats all that impedance matching stuff and your video was really helpful. The only thing is that, even though we can search for the book you pointed out, the camera didnt focused on the ISBN, so we couldnt see it. Could you please put it in the video as a tag? Thanks!

[@wolfgangkemptner8702]

question: can useing waveguide connections compensate for lack of AC-coupling and grounding of ports?

[@linhnguyen-cz6dd]

Hello, Thank for your support, but now I am design a impedance matching circuit for chip CC2650 of TI. And the impedance between tow PIN P and N of that chip is Zs = 45.070 + j*42.709. So how to calulate matching. I see your example Zs just like a resgistor. I hope your reply as soon as possiable!

[@linhnguyen-cz6dd]

processors.wiki.ti.com/index.php/CC26xx_Optimal_Load_Impedance it is application that I want to do.

[@mru_33]

Very nice explanation. Could you do a video on frequency band matching or Chebyshev transformers please?

[@dino5199]

Thanks for the great video, just a question: In what case would the voltage across the load resistor be greater than the source voltage? & why. Thank You

[@wagsman9999]

brilliant - thank you

[@Master_zzz]

at 07:00 you calculate the total impedance of r and c in parallel (z = (Xc * RL) / (Xc + RL). your answer is 75 -j263. How did you calculated that? I get a different answer (221ohm).

[@mike65535]

+Vincent B I got the same answer as KF5OBS, but it took me a few tries.

[@Nikkuuu69]

Thank you so much for demonstrating this! There is one thing that I have no experience with, and that is calculating the complex impedance of a resistor and capacitor in parallel. I checked your web page and was surprised by the answer. Do you know where I can find an explanation on these calculations? I have not worked with complex numbers a lot, but I have a book here I can use as a reference. Another small question, let's say the resistor in your demonstration was not purely resistive, and also had +j10 ohms in series with it (inductive), could you ignore that value, and just subtract the j10 from the final series inductor to make it j253 instead of j263?

[@alfietankokleong]

(-284j*1000)/(-284j+1000)-> (-284000i) / (1000-284i) Multiply numerators and denominators by (1000+284i)/(1000+284i) = (-284000i)*(1000+284i)/(1000-284i)*(1000+284i) = (-284000000i+80656000)/1080656 = (80656000-284000000i)/1080656 = 74.6361469-262.8033343i

[@mpgorans]

Is it possible to receive voltage gain purely from passives (a pi-matching network specifically)? I'm trying to amplify a signal from my antenna, but an RF amplifier is too power-hungry for my system.

[@BlueMonster78]

Can you show how it's done when the source impedance is higher than the load? Say from a QRP perspective. Say you have a colpitts xtal oscillator driving one stage in class A, depending on the transistor/the bias you may have 200-300 milliwatts out with an impedance of 200 ohms or so, that you wanna match to 50. I don't exactly follow this: Update (04/06/2013): I previously wrote that one can not match a high impedance source to a low impedance load. That is incorrect. Naturally, it works perfectly fine the other way around. One only has to switch the position of the load and the source. Switch all source and load in all equations? :) Thanks much!

[@enaviasky]

OH! Thank you. That finally clicked.

[@jagadeesh103]

Is the Q formula same for complex source and load?

[@VERGIS92]

what if you have an inductive load antenna, say 5+J100, do you need to add inductor, or just a capacitor in parallel?

[@BalticLab]

+VERGIS92 Capacitor in series.

[@JackSquat54]

I don't understand subscriber questions like, ' How do i get into RF '. It is too vague a question. What is meant by ' get into '. Is that similar to ' How do DO RF '? It sounds like a comment by a college freshman who hasn't done any reading on RF.

[@mohammedlokhandwala3295]

Fantastic!

[@josepaul2000]

How much does a directional coupler like that cost?

[@mike65535]

+Jose bfy.tw/3zT7

[@brenth5052]

Thanks bro!

[@BalticLab]

Done and done. ISBN-13: 978-0750685184

[@engeng741]

Thanks a lot

[@yoda8693]

The best way to "get into RF" is by reading a basic electromagnetics engineering textbook, like the one available on www.ece.rutgers.edu/~orfanidi/ewa/ which is freely available for personal and educational use, and then probably continuing with a RF/microwave engineering textbook, like the one by Pozar. But yeah, the free one above should let anybody get a first impression of this amazing field. Shortcut ways may be a short cut, but in the end may cost months and years of time wasted on playing with stuff that ends on a level far sub par with the one you'd end up with investing that half year to dig through the above mentioned book, and ending up "a wizard" that actually understands the stuff behind. With RF background, the formulas used in this vid are easily understandable, but without that, I do not really know how anybody would use this theory to anything else than a "cookbook" approach to a L-section. Even the basic complex maths needed here is not entirely obvious for someone not used to the stuff, but still takes only two weeks worth of study to master at the level needed in most, even advanced, RF (basically rehearsing trigonometry and exponential function properties, complex numbers and arithmetic, de moivres and eulers formulas, phasor notation and then some problem solving for practice)!!

[@KelvinLeUT]

good stuff

[@SilntObsvr]

"What people built at home" a hundred years ago will earn you a nasty email from the FCC amateur police if you put it on the air now. Harmonics, chirp, drift -- all built into those primitive radios, all banned. Pick a circuit diagram from 1919, and you'll have to quadruple the number of components just to meet current spectral purity regulations -- if you can even find a way to make it legal. Not saying don't experiment -- but you need to do your experimenting with a dummy load and o-scope, not on the air, if you want to stay legal.

[@karaboga5038]

great video but fan noice kills it