#208

This video illustrates how RF (radio frequency) standing waves are created in transmission lines - through the addition of the forward (transmitted) wave and the reflected wave that results from improperly terminating the line or matching the load or antenna to the transmission line impedance. I have done several videos that relate to transmission lines, terminations and reflections - all of which tell a piece of the story. This video is another piece, and I hope it helps you to understand how standing waves are formed and what the "look" like. This wikipedia link has some great graphics (shown in my video):
en.wikipedia.org/wiki/Standin...
Here's my video on transmission lines and terminations:
• #143: Transmission Lin...
Measuring the length and impedance of coax:
• #37: Use a scope to me...
How a directional coupler works:
• #196: How a Directiona...
Measure velocity factor of coax:
• #162: How to measure c...
RF Detector Probe used in this video:
• #161: Circuit Fun: a s...
Brilliant mechanical explanation and demonstration of wave propagation and reflections, courtesy of Bell Labs:
• AT&T Archives: Similia...
...and if you read this far, here's a challenge...
Brownie points to you if you can tell me how I created the "sliding" waveforms and displayed the static standing wave in the first half of the video.
Update: This video got posted on Hackaday!
hackaday.com/2015/08/06/visual...

[@AppliedScience]

That is so cool! I've never seen RF power measured at different positions along a transmission line like that. I guess it's no surprise that it works, but it's always nice to see theory shown with an oscilloscope probe and a steady hand.

[@MichaelOlsen-Engineer]

Brilliant demo and explanation. Thanks for sharing!

[@fdutrey]

Applied Science Ben and Alan, you guys should meet up and do a video.

[@w2aew]

Frédéric Dutrey I would *LOVE* that - too bad we're at opposite sides of the country!

[@TheMrTape]

***** If only there was a means by which you could collaborate and share data in real time over long distances. I long for the day when that becomes reality.

[@w2aew]

Yeah, maybe when someone figures out this inter web thingy ;-)

[@softwarephil1709]

Outstanding demonstration of standing waves!

[@Thesignalpath]

Thanks Allen. I remember when we did this experiments when I was an undergrad during one of my courses in the lab, I had a "WOW!" moment which changed my perspective forever. :)

[@w2aew]

The Signal Path Blog Yes, there's nothing like "seeing" things like this - really makes it "click!" Thanks for the comment!

[@EETechs]

***** Can you make a video explaining type 1 through 3 op amp compensation networks used for switch mode power supplies? Also, what does the "s" mean in (s+1) term in control theory for compensators and what does the H(s) function stand for?

[@w2aew]

EETechs H(s) is the transfer function of the loop expressed using LaPlace transforms. This would be a more complicated topic and would likely have to encompass a few videos. I'll put it on the list though.

[@bryceroberts581]

This video is the absolute gold standard for demonstrating standing waves. A wiki page is one thing, but seeing the RF power minima and maxima being measured on an actual transmission line is quite another. Fantastic work W2AEW! 73 de W6PGS.

[@yurikvelo]

one more animated visualization from me (made in HFSS) for coax line ypylypenko.livejournal.com/42947.html

[@Parirash123]

Wow, I never thought that I'll ever witness RF Standing wave so practically.

[@MichaelLloyd]

You are very good at explaining somewhat hard to understand "things" in a way that makes them understandable. Thank you.

[@bain5872]

Michael Lloyd I agree. I've never saw anyone else do it as good as he does.

[@hineko_]

I'm starting to think that utube is much better form of education than the universities. They never explained it this good at my U. In my case it was like here take this bunch of formulas, plug in numbers, calculate, congrats here's your bachelor's.

[@w2aew]

You just have to find youtube instructors that explain things in a way that works for YOU! I'm glad that my videos do that for you.

[@schwinn434]

Unfortunately, I wasn't a very good student (and that's my fault), but I do think Alan's videos are much more educational than any lectures I received in my EE baccalaureate degree program; my lab classes didn't even use real oscilloscope probes (and, I had no knowledge what additional influences a home-made probe would have introduced , when high frequencies were used in a circuit- besides, we didn't have the equipment to generate anything over 200 megahertz, anyway, if my memory serves me well). We just used coaxial cables, stripped to the conductor on one end, with a BNC connector on the other end. It's embarrassing for me to admit, how much basic electronic science I've learned from Alan's videos - that I should have already know from my formal education as a EE student. I sure hope my university does a better job today educating future engineers - but, I doubt they do, since I can't imagine the lab classes having expensive modern electronic test equipment in them (too expensive). It blows my mind to think of the money wasted in education, when they could just buy some decent test equipment, and pay the correct people to demonstrate how to properly use the test gear - and what the equipment is measuring, and why; And I do believe in the idea of public education, and consider myself to be very much a liberal. However, just today I was reading, in our local paper, about our local convention center receiving an education award for educating children middle school and high school children- not sure of the exact grades; this convention center puts on these very silly plays, which are supposed to be comical (I guess), for which they bus in thousands of kids to watch, during the school day, and call this science education. I started watching one of the plays concerning science, and it was a joke (truly a joke), IMHO.

[@patrickbouldinkm5l143]

@@WECB640 I think Walter did a great job with the pendulum explanation.

[@ernieschatz3783]

Your organized thought, visual aids and practical application is spot-on to me. So many You Tubers want to race through a subject without coming up for air. Also, you don't seem to have the tendency of diving down rabbit holes to the point where I feel I've been through a spin cycle! I rarely have to pause your videos either. I revisited this vid because memory is always the first thing to go!

[@rameshbabu2704]

Greetings from India, Alan you are my greatest RF guru

[@jmartin9865]

This was fascinating. As a newish ham I never really got SWR until watching this. Thanks!!

[@BMRStudio]

Best RF teacher on the planet!

[@jmex46]

Thank you for taking the time to demonstrate standing waves. Great work!

[@grantgiesbrecht2236]

Wow, I've never been able to see the effects of impedance matching as directly as you measured it here. It's very cool that you were able to measure the nodes and antinodes. Time to break out some PCBs and give it a try!

[@paulp1204]

That was a terrific visualisation of an effect I understand, but had never witnessed so clearly. I've watched many of your fabulous videos, Alan, but this one has somehow eluded me. Glad to see it today. Thank you.

[@Aemilindore]

Thanks for letting me see this phenomena. Although yuur previous video spoke of it, it was tough to believe it. This video gives the edge. Thank you so much.

[@daic7274]

Best demonstration of standing waves so far, and a useful function of persistence on a digital scope. Thank you.

[@stpaulji]

Thumbs up! Great video to visualize standing waves on TML. The first time that I have seen such a kind of visualization.

[@borayurt66]

Great video! SWR explained without getting drowned in formulas and theory etc. Loved every moment of it. Thanks!

[@naftilos76]

That is the coolest thing i have ever seen. Illustrating standing waves with this trick was just amazing. Great thinking! Bravo!

[@_egghead]

Thanks man. This does not only made me understand standing wave, but i now visualize the concept of transmission

[@RocketRoberts]

So great to see someone who knows the material explaining it well!

[@martinhodge921]

In 10 minutes you've completely demystified standing waves for me. Thank you!

[@KB9DKA]

Amazing demo on Standing waves. Actuall measurement of the standing wave pattern on the live transmission line is absolutely unique. Much appreciated W2AEW !

[@pentachronic]

Brilliant!! Never really understood this. Now I do !! You definitely have a gift for breaking apart the complex and showing us what is really going on.

[@RedlabsTV]

Wow, your visualization methods help a lot to understand. Thank you!

[@octavmandru9219]

You are a teacher that can do magic. Thank you for the effort you put in these teachings. Have you considered a teaching career?

[@w2aew]

Maybe I'll teach after I retire...

[@Avionics1958]

I dont think any body can explain this any better and any clearer than you have Alain. You've nailed it.

[@ve6kk]

Thanks so much again Alan. I wish I had your vids and ideas for test fixtures when I was teaching Engg. Techs. Standing waves are one of the hardest ideas to grasp so I sent this link to my basic ham class. And so happy that the classic Similarities of Wave Behavior is on KZbin too. Cheers

[@erikchen8897]

amazing, really helped me understand standing waves

[@RohanSingh-py5cv]

So awesome!! I'm studying about Transmission Lines right now and it's so cool to actually see all the theory presented in the books!

[@MichaelShaw_vk2hms]

This an excellent demonstration of VSWR. Thank you!

[@insightfool]

This is such a great intuitive explanation of things. Thanks so much!

[@yaghiyahbrenner8902]

Fantastic video. so much knowledge compressed in only 10 mins.

[@JustSomeGuy1967]

Your videos are always great. I'll be waiting for the next one !

[@PapasDino]

As usual you make a complex topic so much easier to visualize in real life! 73 - Dino KL0S

[@gerrysweeney]

Thanks Alan, every time I watch one of your vids I know more about RF theory, I really like your practical illustrations of this sort of thing.

[@w2aew]

Thank you Gerry!

[@wa9kzy326]

Fantastic presentation. Back in the day, we saw similar demos using "Letcher" wires. Nothing can be more informative than actually seeing the reality of the electric waves in their natural habitat, so to speak. Well done. In all of your videos, you have proven yourself to be a great teacher.

[@rylanbrowne5658]

You make it so much easier to understand transmission line theory. It's pretty hard to visualise it just by reading about it.

[@07kandarp]

Amazing video as always, I was having a discussion with a friend of mine as to why the normalized impedance would repeat itself on a transmission line every half wavelength. This proves it. Also that is true for any termination except matched termination aka 50 ohms in most cases. Sits really well with the smith chart also. Alan you are true genius.

[@RatedA4Aliens]

Simply the best, this should be the supplementary video material for any transmission / Power related EE course

[@jonka1]

Beautifully and perfectly illustrated.

[@CalebDiT]

Great video! It's so nice to see things come together in reality after studying this stuff on paper.

[@SnowyTurtleXD]

Great video! Really helped me in understanding transmission lines for a project I'm completing for my PhD. Much appreciated!

[@jspencerg]

Excellent practical demonstration of SW. I used to have students experience wave additions in the floor with 'super' slinkies. Similar wave behavior in different wave mediums makes understanding wave behavior so interesting.

[@TheBdd4]

Just saw saw this excellent video. I hope you are compensated in some way for all of your vauable videos! I have learned so much from you.

[@mattkarlgaard1310]

Thanks for sharing! I watched this video with my 9 year old and it got him excited to break out his littlebits.

[@DonzLockz]

Amazing to actually see it in action! TY

[@forestfolks]

Incredible! I've been struggling to understand SWR and this helped me a lot!

[@acestudioscouk-Ace-G0ACE]

To be able to "see" practically what the text books teach, is just amazing. It really helps to take the information on board. Thanks. You have so much content, I'm working my way through. Watch one, think and absorb, watch another... I could be half educated by the end of this! LOL

[@Impedancenetwork]

Ohhh man! That was awesome to see. I am literally learning about standing waves in my electromagnetics class right now. My brain started hurting so I stopped to watch some youtube. I just happen to type in standing waves and got this video. So nice to see what they are talking about in my EM book. All the equations and derivations just make you blind. This really helps me understand what is going on.

[@makerspace533]

Nice demo. I have a large slotted line and an HP 415E I use to demonstrate SWR. If the crowd is very large, I hook a small amp and speaker to the amp output of the 415E so the 1000Hz tone can be heard around the room. I usually get some comments about the archaic equipment. Then I like to point out that this is the type of network analyzer that was used to design the equipment that brought back TV signals from the moon walks.

[@fjs1111]

Awesome visualization of standing waves as well as a description of constructive/destructive wave interference.

[@dank8981]

This is really awesome. Really appreciate the demo.

[@OscarJimenez-qo8go]

Fantastic video. Please continue making these informative videos on RF!

[@hubercats]

Another awesome demonstration, Alan. - Thank you! - Jim

[@ekobbl2011]

Best explanation and practical demonstration ever! 4 thumbs up.....

[@UberAlphaSirus]

I don't know how you do it. I could read for a week on all this voodoo magic, and you Sir, sum it all up in 10 minutes. Your channel is one of the best I have have subbed.

[@moustaphamuhammad7013]

Yes, yes exactly!

[@ae6850]

I've been following whenever; your way and material of explaining things is it. Thank you Sir. ae.

[@Resonant87]

thank you so much for these videos you make understanding electricity sooo much easier.. you're doing amazing work

[@moustaphamuhammad7013]

I can't stop watching that video over and over again. you are the master of desk experiment.

[@VintageLabSilvioPinheiro]

Genius again. The best video i saw about stand waves. Clear, direct and simple. Sorry about my rusty english. Huge 59 S9+40 73 DE pu2srz

[@DAVET38]

Another very interesting video Alan. Thank you.

[@cyberphox1]

That is an excellent video on standing waves.

[@SteveTjiang]

Awesome video. The visualization really helped me understand SWR

[@EigenA]

Great job on bringing my Emag class to life. Thank you.

[@DucatiMTS1200]

Magic explanation and demo!

[@robertcalkjr.8325]

Thanks Alan. Another great lesson.

[@LarsBerntzon]

Very nice and clear to see how it behaves

[@sherwintiongson8197]

This is a fantastic video.

[@gurgen_a]

Really good demonstration!

[@karlfell3768]

Another fantastic and informative video. Keep them coming. Karl

[@DenysSene]

really great way to explain SWR.

[@RoboGenesHimanshuVerma]

So enjoyable and clean

[@radiofun232]

Perfect demo, 5 stars (cannot be explained better).

[@alucardt3hvampireguy]

I've had great trouble in the Electromagnetics course because while using Smith charts, we never went over what the transmission and reflection coefficients, nor the VSWR actually represented visually. Thanks so much for clearing this up.

[@davidgmos]

Great demostration!

[@sergiogarza8933]

Phenomenal video, thank you so much.

[@davidcasement1296]

Nice Video. I clicked like and shared with some coworkers who are learning about this for FM Broadcast (Low power).

[@TheStoneWhisperer]

Well I feel like an infant listening to their first words! OMG! Some cool stuff here! I understood about 50% of it, but I took what I could from your words of wisdom! Thanks!

[@alperenalperen2458]

A very clever demonstration

[@andrewlamoureux2251]

Great demonstration!

[@dannybeckett01]

Extremely good demo

[@davidausterman5915]

Brilliant video

[@bgroisma]

very clear and didactic video, congrats !

[@yoramstein]

Another great video .

[@nlo114]

Excellent demonstration. This would have been good at my tech-college. It took me ages to understand this straight off a blackboard, in a class of semi-interested students.

[@tank618]

Excellently done!

[@CoversTavo]

Wow dude... Excellent explanation! :)

[@williamwalker8107]

I like this practical literal demonstration of SWR stuff.

[@larrywiniarski1746]

Very very very very nice video. Thank you so much.

[@dougpeterson1925]

Great video.

[@rkdehury]

excellent . great way of explanation.

[@lupojacobo9892]

Thanks for sharing your knowledge

[@annacersongor8553]

So beautiful ! Thanks sir, thanks a lot.

[@kevinobrien8803]

Fantastic video

[@saarike]

Absolutely great!

[@EVERY.CIRCUIT]

I like your video, thank you so much for this video😊

[@kieranj67]

Thank you for this excellent video

[@wuftymerguftyguff]

Thanks Allen, very useful

[@robv3872]

amazing channel!