Impedance Matching Basics

Learn the basics about impedance match and how impedance matching networks works.

Impedance matching is an important topic in RF and Microwave electronics. In this video, Gregory shows how an LC impedance match network was designed to match a 150ohm load to a 50ohm system.

The designed network is demonstrated using time domain signals and measurements of S11 with a directional coupler.

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[johndavis]

The problem is that this does not work for wideband applications.

[yakovdavidovich]

What a wonderful video, thanks for making it the way you did. I kept track of everything, but a few of your explanations were much better than I usually find in textbooks, and helped clarify some things for me.

[wnekuu]

Seems interesting vid but I just can't watch it due to all that quick cuts in the middle of sentence, it's so annoying it really makes it unwatchable :/

[td]

Helpful. My knowledge base does not include much about impedance, yet. Your video was helpful, because 1) you explained why matching is important/necessary, from the prospective of transferring power between two devices and 2) you showed how a) the matching network is constructed and b) how it works via plotting/calculator. I know that I need to learn more about impedance. However, it is easy to get lulled into just throwing an op amp into the circuit design to dance around the challenges of actually learning about impedance.

[therfnoob]

great video!

Could you also make a comment about the difference between a transformer approach and a Capacitor/inductor network for matching impedance? What is to be preferred?

Also, you have an amazing assortment of components in your lab! :D
Could you comment of what you have there, and make a lab tour?

Keep up the great work!

[watson]

Hi, great work on this content. It's good timing for me as I'm trying to design a linear amplifier for 70 MHz (4m Ham band). I am using MRF101an and hoping for 20 dB gain, 1w in 100w out. I have the 1 watt sorted (-;
I have been using smith chart software to calculate the necessary values to match the output of the device ( I am being lazy and using 6 dB PI attenuator for the input so the preceding circuit sees a good match). I found NXP provide some reference circuits (closest is 50 MHz, and one at 81 MHz), they also give some values of Z load and Z source, I discovered I could use just series inductor and shunt capacitor. Why did you use an extra series capacitor? Maybe to give more flexibility for tuning, also I guess it works to decouple AC/DC?
Anyway, again, thanks for this video.

[Akshay-fgyn]

I voice searched for impedence matching of physiology and i found this 💀

[loretti]

Are you Brazilian, I suppose? Great content! Do you have any channel in Portuguese also? Or any books, material or blog?

[iwbnwif]

Great video - thank you!! Please can you say why you choose 5 as the Q factor?

[like_cabezon]

The best impedance video i´ve ever seen, very useful the distinction of power and voltage and current and even better the simple explanation of how to use the smith chart in a basic way now I can use this In a problem that I found the other day testing an oscillator because I wanted to connect the oscillator to an RTL-SDR to check the SDR and the oscillator and the problem was that the SDR has an input of 50 ohm and my oscillator had another output impedance luckyly I found on the internet some methods to compute the output impedance of a circuit and now with this knowledge I can transform the 700 ohm output to 50 ohm. Keep going with the channel beause not much channels talk about this topics and yours its one of the best of youtube in this area.
P.D.: I´m very intrigued about the new update with the new design of the bpsk transceiver.

[pierfrancescograzioli]

Ciao bel video, ma tu sei italiano? Nel video si vedono libri in italiano dietro di te? Complimenti bravo👍👍

[cyrillehasdenteufel]

Hello Gregory i would like to ask you about your directional coupler which you are using in the video ... could you please share the reference and where i could buy one .. the goal is to measure the output impedance of an small RF signal amplifier Parameter S22 .. thanks in advance .. Greetings from France

[TheSudiptheory]

For mini FM transmitter it's required 50 ohm antenna and cable. RJ 58 and RJ 174 both are 50 ohms. If I use RJ 174 cable, It would be perfect for transmitter or not? Could you please tell me this?

[omsingharjit]

how to kno that wire is 50 oh and it also depands the thickness and legnth of the cable just in dc ohm law ?

[andrewverran]

Hi, i have an old Marconi Step attuator which has 75ohm input and output, i would like to convert it to 50ohm input and output..i will only be using it with cb radios, ie up to 30mhz.
Can i use this approach?
Much appreciated

[enriquegonzalez]

what about low frequencies as in the audio range....

[waterfuel]

Help needed! How do I match impedance of inverter16v AC output SOURCE
to 16vAC isolation transformer primary, that I have to hand WIND, for 4
ohms load of 32v AC 6 amps secondary ? Do I use the ohms of primary 16v +
12 amps division or the resistance .06 ohms of inverter output contacts
terminals at 20khz frequency? Voltage and turns ratio same as 1:2. The
online formula for inductance value of turns requires reactance value in
ohms, at the frequency of source.

[thegill]

batteries typically have an internal impedance much lower than 1 ohm, so why do AC sources have such high impedances as 50, 75 ohm, isn't that a lot of Joule loss ?

[robertohernandezsannchez]

Does anyone know how to match the impedances of some EMG electrodes to an AD620?
The circuit always saturates or does not amplify anything

[Marg]

I'm doing the IEEE IMS competition for this year and this video helped a ton. Thank you!