This video acts as an impedance matching network between this topic and my brain. Perfect!

This film is a real gem. I'm an engineer (and used to be a professor) and the clarity of explanation in this film is exceptional. It is the best explanation of SWR that I've come across to date. This man would have been a favorite teacher had I had the opportunity to sit under him.

This dude has a very slightly evident grin that appears when he knows he's explaining something enlightening. You can tell he loves what he's teaching.

You can tell from his expressions that this guy is having a blast talking about this.

My dad worked at Bell Lsbs and I had a basement full of test gear and jars of vintage transistors to toy with as a kid, and consequently have always had electronics and radio close to my heart and am still learning the deeper aspects of those subjects. Bell Labs was an amazing place, there were actually two, one in Murry Hill, NJ, where the transistor was invented, and one in Holmdel, NJ, where my father had worked and did quite a bit of transmission cable work and later fiber work. There was a white water tower there at the campus in Holmdel with 3 support columns, which oooked suspiciously like an oversized transistor; the joke was someday someone would paint E, B, and C for emitter, base, and collector on the bottom of the tower to properly label the “leads” of the water tower. That kind of research is where it’s at, we need to get back to that collaborative multidisciplinary approach with a big center and a big budget to push the technology frontiers hard again. For example, the west needs workable fusion power, and the fragmented approach is perhaps costing more in lost time, than it is saving in dollars.

I have learned more about waveform in this 30 minute video than 7 years of being an amateur radio operator. Great explanation and video.

What an utterly gifted teacher Dr. Shive was, and what a gift Bell Labs gave us by preserving his work on film.

Maybe this has been commented earlier in this thread… About 5:30 into the film, John Shive talks about the termination of an electrical transmission line. At first, I thought John Shive was wrong, since I have truly seen the opposite in our lab. What I have seen on an oscilloscope is a wave that returns “upside down” from a short circuit termination, while an open circuit termination gives a reflected wave with the same phase as the incoming wave. But John Shive talks about a current while an oscilloscope measures voltage. At an open end, the law of conservation of energy results in the pulse having to return to where it came from (since it has nowhere else to go). Going back, a current would have to pass through an imaginary amperemeter in the opposite direction compared to its original direction, thus giving a current with the opposite sign. So, John Shive was right about the current. Why doesn’t the voltage change polarity as well? This also has to do with energy. The termination and the ideal wires do not “steal” (convert) or store any energy. Therefore, the sum of energy from the forward and the return wave must be zero, E(forward) + E(return) = 0 and E(forward) = -E(return). The minus-sign comes from the inverted current, therefor the voltage can’t be inverted. Anyone who agree with me?

I wish I would have had someone like him when I was studying to get my Amateur Radio license, I might have accidentally learned something instead of just memorizing the correct answer.

Amazing. So clear and direct. I find the further I go back in history, recorded science lectures seem to just make way more sense than today's classes. I'm not sure why. Maybe they weren't trying to teach so much at once then, and they had a script, so the material was presented in a very logical order, but this is definitely easier to understand for me than a lot of more modern videos that seem to just "wing it".

As an old-school extra-class amateur radio operator, I recommend this video as an aid to understanding feedline/antenna matching.

Information is sliding so pleasantly and efficiently into my brain! So much respect for this era of engineering.

From around the 21:00 mark, interstage SWR and it's importance is well demonstrated. Also, for anyone thinking that the diagrams around the 05:00 mark and onward are incorrect, they are not. The discussion is about current not voltage and is explained as the film progresses. This demonstrates the importance of paying close attention before drawing a conclusion.

This film is precious! The mechanical analogue equivalent is the perfect medium to explain concepts like impedance mismatch and standing waves. It is easy to see the mechanics by which a high SWR can destroy the output stage of a transmitter.

At 5:58, there is a mistake on the chalkboard. If the transmission line is shorted, the voltage reflected will be inverted. This is because the current will flow on the minus terminal momentarily during the return propagation time before the output is zero due to short circuit condition. Otherwise, this is a very informative video.

This has to be one of the greatest lectures of any kind that there can be.

This is so much more than clear, concise education: It's poetic. Absolutely amazing.

look at the smile on his face when he talks through the megaphone.

I have been getting into ham radio over the past three years and this video is one of the most helpful things I've found in my learning journey.

Multiple "aha!" moments, absolutley Priceless!!!!!!

This is gold. I am amazed how the concept of impedance can be applied to so many things at once and how waves are all similar in their nature. I went from having no deep understanding of waves to seieng patterns between different physics areas in one video.

We just don't have awesome professors like this anymore. I could listen to this guy for hours.

WHO WOULD DISLIKE THIS!?

7:30 is the visual demonstration of how a standing wave forms that I’ve been wanting for so long

A picture is worth a thousand words, it is said. This demo of SWR is worth a million. I am an amateur radio operator, and thought I understood SWR in transmission lines. I certainly understand it a lot better now.

This a great video .Truly a treasure. A slight correction would be that the free end of the mechanical system is analogous to an open circuit in an electrical system. While the restrained end in a mechanical system is analogous to a short circuit in an electrical system.

As I get into amateur radio, KZfaq brings up these beautiful old educational shorts that demonstrate concepts so succinctly and accessibly. I'm so lucky to live in this age for the accumulation of information that's been possible with the internet.

Absolutely fantastic description of waves, impedance matching and SWR! As a radio amateur, this explanation is wonderful. Thanks for sharing!

Fantastic video! Wave behavior mathematics are difficult to learn at the beginning, and it's not clear what is physically happening in, for example, radio or AC transmission, and why impedance matching is so important. This video makes the reason that is important and how it works clear. I love it!

I remember teachers like this as a child, pleasant, refined, disciplined, and often very conservative. They did not suffer fools lightly. It is a sad reality that the ability to calculate in mathematical terms is extremely difficult for so many people. The best way to counter this condition is through constant repetition. Practice practice practice from a young age, as soon as possible. The torture of that exercise will pay huge dividends later in school. So many geniuses become lost in this struggle, the old left brain right brain argument. Matching the imaginative dreamy brain with the analytical is another form of impedance resulting in miraculous new innovation. Happens every time.

I've known about most of these concepts for decades, but now I have a real understanding! This is an amazing film, and Shive is absolutely brilliant in his capacity for imparting knowledge.

This is so much better than any explanation I've encountered in many textbooks.

this video is so addictive, the more you watch, the more you like

The reflection formula at 18:15 made my head blow up. I am unable to continue learning wave behavior as my... well..... my head is gone.

actually the best impedance explanation I’ve seen👍

Wish I had this guy as my teacher! Great video!

I love the honesty and openess of practical demonstrations

I wish I'd seen this a few times at college! I could have progressed a lot farther a lot quicker in my career with this Gentleman teaching.

Watching this in 2022 and it's still extremely useful and clear with building an intuition of transmission lines.

Exceptional tuition and understanding by a most clever man.

Genius is making the complex simple. What an amazing guy. We are very fortunate a small piece of his knowledge was captured on film.

A very rare and exceptionally talented teacher.

I have been looking for this for 30 years. I went to the Navy Electronics Technician A School. It is the best visual demonstration of transmission lines.

Amazing Amazing Amazing !!! The examples by Dr. Shive are way better than today's 3D & digital simulations !

When AT&T was a great company to be admired.

It's a fantastic presentation - very clear, concise and to the point -

Wow-- what a terrific explanation. Every instructor could learn from his relaxed but deliberate pacing-- gives the student a moment to reflect on what he's saying. For anyone wanting to learn more about what an amazing place Bell Labs was, I really enjoyed Jon Gertner's book.

This video is one of the best that mankind has to offer.

Hi viewer's. Is there a mistake in the drawing on the black board at 04:52?.In an electrical transmission line the reflected wave is inverted when the line is shorted at the end. But its shown that the inverted reflection occurs when the line is open. Is my understanding correct? Viewers kindly clarify on this.

10:51 "impedance" being the ratio of "cause" to "effect" 21:00 It's true, our world is abound with these examples! 26:57 was an insightful remark from Dr. J.N. Shive, "Waves of all types behave alike."

Old True school of amazing physics it must be incredible to have such a fantastic teacher at least once a time in life, this can change the mind and the way of thinking physically for ever.

This video is a true gem

(May 2023) - This professor is a passionate GENIUS!! Why have I never heard of this teacher/clever demonstrator before?!

Best demonstration of wave behavior that I have seen so far.

Fantastic demo!! Great description of SWR!

Love the use of big fractions fractions at around 18:35. When I was in school, oh so long ago it seemed perfectly intuitive for me to use =>1 fractions. I was told that this was wrong, somehow -- though my work was accurate, correct, documented, and mostly legible, I tended to skip the needless reduction of fractions at every step that they expected it of me. Conferences were held, admonishment was dolled. I now feel vindicated by this verification that there is no shame in expressing a number as "seven halves," as everything presented in this film is perfectly cromulent and expertly explained. Thank you.

Very informative and well presented. But I think I noticed something possibly incorrect. At about 5:48, the speaker mentioned that in an electric transmission line, an open end results in a reversed polarity returning wave, and a short circuit end results in a same polarity returning wave. In another KZfaq video I viewed, "Tektronix - Transmission Lines", the opposite was demonstrated to be true using an oscilloscope. Which is correct?

this channel has become one of my favorites on all of KZfaq, and why youtube is so amazing. i'm one of those math-challenged liberal arts majors (lol right) but i found the UNIX video *really* cool as a backgrounder on computer science in general as well as UNIX, coding etc etc. this vid is incredibly educational as well. awesome stuff, ATT.

Brings back memories of the Newton's Cradle I had on my dresser as a kid. A visual reference of the physical characteristics of things that occur and can be seen throughout the natural world around us. I want to build one of these machines. It would be great at parties. BRILLIANT!

This video is gem. The best explanation of standing waves I've ever seen

Simply Brilliant.

This is a great video. Clear and well organized and the physical machine really shows off the concepts easily.

BEST VIDEO EVER teaches alot which universities cant teach in 6 months

surfs up Waves awesome dude. Maximum shear occurs at nodes in structural analysis. FEM today makes this much easier to calculate. Awesome film Thanks.Shalom

A guitar string has a standing wave ratio of infinity, and gears and levers are impedance transformers promoting the transmission of the energy of motion . Just two of the many things I've learnt in 26 minutes watching this lecture.

Thank You AT&T Channel

Un bijou à conserver pour les futurs intéressés aux ondes. On a envie de retourner à l'école.

A great explanation and a stylish presentation! Really enjoyed this.

Remarkable outstanding presentation! imho Very Thanks and Very Well Done to this exceptional teacher (to his memory of course).

Amazing explanation of SWR!

Really enjoyed ! Impedance matching looks so simple and effortless...

Best ever seen wave tutoriral

Absolute genius. Masterpiece

Excellent point about studying an area that deals with waves extensively allowing you to understand any other area that where waves are fundamental to the field; absolutely agreed. Particles and waves are what everything eventually comes down to.

Responding to +HitAndMissLab comment from a few years ago . . . This video also gets the acoustic wave reflection wrong (kind of). The reflection of a acoustic displacement wave from a free end is upright, while the reflection of an acoustic displacement wave from a rigid closed end is inverted. However, we don't typically measure displacement waves for acoustic sound waves. Instead our ears and microphones respond to pressure instead -- and pressure has phase quadrature (90 degrees out of phase) with displacement. So, the reflection of a pressure wave reflects from a free, open end is inverted, and the reflection of a pressure wave reflects from a rigid closed end is upright -- the opposite of what happens for a transverse mechanical displacement wave.

Wow, Thank you, Perfect demonstration ( Beautiful handwriting btw. )

Incredibly good explanation for how SWR works!

Wow, that was the best explanation of resonance and SWR I’ve ever seen or heard. Where’s the subscribe button.......

This is such a wonderful and very visual explanation of the basics of waves. Thank you for preserving this awsome content and making it accessible!

May you rest in peace. I deeply appreciate all the knowldge and the laugh. I needed both.

Beautiful handwriting and drawing.

This was freaking awesome.

I watched the entire video. I actually learned something.

I remember seeing this film ... High School electronics class I think. Great subject .... Goo d presentation!

One of the best videos /films I have ever seen in my life !

Nice demonstrations of mechanical 1/4 wave and taper matching elements.

thanks a lot for the perfect analogy. For years I was struggling to understand the propagation of highspeed currents in the circuit boards with different loads.

Damn, this guy is good. He did this all in one take?!?

this is a superb demonstration and lecture on the general topic

At 05:09, I think that load impedance is not correct: positive reflection happens on open circuit (not short circuit), and negative reflection happens on short circuit (not open circuit).

How is it that some video form before I was born is better able to explain all these concepts to me than my oh-so-modern schooling was? Very nice video.

The greatest video I ever watched...😇

Really thought provoking. Excellent.

Insanely helpful, no matter how old it may be (older than me by 5 years to be exact). ;)

This is so amazingly clear and easy to understand!

Best explanation of swr I've ever seen!

good advice! This is ehat I did as I work on shortwave frequency that I can only mesure with my oscilloscope I decided to experiment also with light and audible frequency as they all behave in the same way but it is easier to understand them when actually we can experience them by hearing or seeing (like sound or visible light) .

Forever great.

wtf i love at&t now thanks for the informational video

Thank you for posting this.