Why is the Smith Chart one of the scariest charts in electrical engineering? Sponsored by Incogni - use code veritasium at https://incogni.com/veritasium to get an exclusive 60% off your annual subscr
Honestly I am watching veritasium since 2018 and I am 18 now. The way it turns my curiosity on is still unmatched.❤❤ I believe the teaching philosophy of this channel is what makes one think clearly. Thank you veritasium for teaching stuff we rarely used to notice.❤
I'm an RF engineer. This field can be really difficult for people to get into, so it's great to see someone trying to take this topic to a larger audience.
I had a few things I wanted to add here:
1. When discussing recieved power at around 7:00, you say dB but the label says dBm. These are two different and distinct terms. This distinction matters a lot because dBm is the absolute power (dB relative to one milliwat), and dB is a ratio. We talk about power levels in dBm and signal quality (i.e. SNR) or losses/gain (insertion loss) in dB. You can add/subtract dB from dBm.
2. The smith chart is not the only way to check an impedance match. We can use a VNA to measure the S-parameters (magnitude of reflection for multiple ports) over a wide frequency range. We will typically use S-parameters instead of a smith chart if we are not trying to match impedances. Most modern RF chips already have a 50ohm match on the input/output, so you only have to match the transmission lines into and out of the component.
3. There's certain critical aspects of transmission line matching that were left out of this video (likely for brevity). Substrate thickness/material, tx line thickness/material, skin
Ah yes the infamous Smith Chart. I'm a retired EE and I remember vividly at my undergraduate days at Purdue this thing scared the bejesus out of me. I graduated and my first job was working at the Motorola Government Electronics division in Phoenix. (Now General Dynamics). My first 6 months there were spent in a training class all EE grads went through to work there. Nobody does this anymore, which is really a shame. In the training class all of us new hires were exposed to every type if electrical engineering they did at that facility. On 2 week session was on RF amplifier design. It was there, working with a very seasoned RF technician I finally understood the magic of this chart. The tech made it so simple to understand it floored me and got me wondering why in the world did my Purdue professors make it so complicated. I ended up being a semiconductor chip designer not an RF engineer but I still remember the shear beauty of this chart and how wonderful it solves impedance matching in RF design.
Looked at this chart three times to understand. This is the most amazing, straight forward way to understand how to match impedance there is. Wonderfully simple and straight forward.
S
Sofia from Daily JunctionHost16 Jul 2026
That Smith Chart looks like a total nightmare to decode at first glance! I love how this breaks down the chaos into something actually understandable. For those of you who've survived these in class, did it finally click or are you still haunted by them?
I love how even a simplified veritasium explanation of transmission line concepts gets very complicated. And this is coming from someone with 12 years of electrical engineering experience.
I love how every other branch of science uses charts to show data, but Electrical Engineering just uses a chart that looks like a transmutation circle to summon a demon.
This is the first Veritasium video where I have a difficult time understanding everything discussed in it, even with the simplified examples. Respect to all electrical engineers out there, literal wizards
Physicist and high power RF/Microwave Design engineer here. Truly a brilliant attempt to simplify this subject in a 30 minute video. Kudos for trying. For the past 30+ years I have been using the Smith chart not only to match transmission line elements into systems but also to teach electrical engineers how to think about RF. At high power, to practice RF Design engineering requires an integration of a few engineering disciplines: Mechanics, Electrical, Thermal (same as RF just different frequency), Materials science and even fluid Mechanics into the physics of waves. Time varying and spatially varying voltages and currents all traveling down a transmission line.
A few nuggets to add to the video
1. Characteristic impedance of any transmission line whether it’s coaxial, microstrip, CPW, strip line waveguide etc. (Z= R+jX) is really geometry dependent, which drives everything in this discipline. Similarly physics is also all about geometry especially gravity.
2. Look up George Gamow’s island treasure puzzle. Alternate way to look at the complex plane.
3. A short circuit that is a quarterwave long actually looks like an open circuit. And vice versa. This RF magic can be used to desi
My professor told us to not make photocopies of the Smith chart, because by buying an official Smith chart, Philip Smith’s widow would get royalties. Buying fresh charts might have cost me a few bucks, but it helped the old widow in some small way. Impedance matching never felt so honourable.
Within the Electronics world, RF electronics engineers are widely considered to be magicians who may in fact be sacrificing goats to make sure their impedances match.
A lot of recent exposure to this graph has been the incredible democratisation of high performance low cost rf tool. The nano VNA and lasmux active probe are incredible tools.
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I had a few things I wanted to add here:
1. When discussing recieved power at around 7:00, you say dB but the label says dBm. These are two different and distinct terms. This distinction matters a lot because dBm is the absolute power (dB relative to one milliwat), and dB is a ratio. We talk about power levels in dBm and signal quality (i.e. SNR) or losses/gain (insertion loss) in dB. You can add/subtract dB from dBm.
2. The smith chart is not the only way to check an impedance match. We can use a VNA to measure the S-parameters (magnitude of reflection for multiple ports) over a wide frequency range. We will typically use S-parameters instead of a smith chart if we are not trying to match impedances. Most modern RF chips already have a 50ohm match on the input/output, so you only have to match the transmission lines into and out of the component.
3. There's certain critical aspects of transmission line matching that were left out of this video (likely for brevity). Substrate thickness/material, tx line thickness/material, skin
A few nuggets to add to the video
1. Characteristic impedance of any transmission line whether it’s coaxial, microstrip, CPW, strip line waveguide etc. (Z= R+jX) is really geometry dependent, which drives everything in this discipline. Similarly physics is also all about geometry especially gravity.
2. Look up George Gamow’s island treasure puzzle. Alternate way to look at the complex plane.
3. A short circuit that is a quarterwave long actually looks like an open circuit. And vice versa. This RF magic can be used to desi
A lot of recent exposure to this graph has been the incredible democratisation of high performance low cost rf tool. The nano VNA and lasmux active probe are incredible tools.