Antenna Theory Propagation

The National Film Board of Canada for the Canadian Air Forces - Great explanation of Propagation

[@ethzero]

Why can't all modern day KZbin educational videos start with an epically uplifting orchestra?

[@connormagill4201]

Thank you Royal Canadian Air Force for creating such an informative and aesthetically pleasing video. Coming from a US Marine decades later, this presentation helped me understand the fundamentals of wave propagation.

[@schitlipz]

Back when Canada was great. Greetings all Canadian avionics folks here. Bob, if you're still around, thanks for the start in the career.

[@danwest7898]

In the mid-70's I used this as a training film (it was old, scratched 16mm celluloid film) when I was a USAF military adviser to the Imperial Iranian Air Force. Yes, Iran was an American ally at the time and the Shah was still on the Peacock Throne. So glad to find it online. For those who think this is crude compared to what you can create with today's technology, it was animated by hand, one frame at a time, just like Walt created Mickey in 1928.

[@PinkeySuavo]

thank you, interesting information

[@thorn9717]

For weeks I've been looking for a video describing WHY half wavelength is SOOOO important in every conductor carrying a varying current. All videos I could find described the standing wave you create at the half wavelength, but failed to describe WHY it radiates that specific frequency. This video does the simple and yet very effective way of doing just that! Thank you to the uploader of this video!

[@itsmetheghost4993]

Another feature of square bus bars would be to generate less rf?

[@artie5172]

I don't understand too? Can you explain

[@andrewknotts2798]

@@artie5172 To make the most efficient and simplest use of an antenna of any length, you want to push and pull the electrons along the full length of the antenna. To do this you’ll be switching the voltage from high (to pull them) to low (to push) whenever the electrons reach the close end of the antenna to the voltage source, and from low to high when they reach the far end. If you waited for the electrons to do this you would have a wave length that is double the length of the antenna (while on the antenna you get the first magnetic peak in one direction but not the comeback peak with the reverse curl [negative sine wave] until the electrons are on their way back. You often want a shorter wavelength and can do this by switching from low to high voltage (push to pull) at 1/3 the length of the antenna and swithching back at 2/3rds so when the electrons reach the end you’re in the same position to switch from push to pull. You can actually add any arbitrary number of full wavelengths after you add the one half wavelength switch. So you could switch at 1/5 of 1/7 and add 2 or 3 full wavelengths after respectively. You’re still in the efficient position of going from push to pull when they finally reach the end of the antenna.

[@sharkpowah]

the simple dipole (basic antenna) radiates at lambda/2 frequency since it's in half period of a sinusoid that you can see at least 1 "back and forth flow" of the electrons, therefore in half the period (half the wavelength) you can send a high quality signal

[@akashk961]

❤😎 Love & Respect to the whole team for making this effort long-long back! It still helps

[@VE9ASN]

I can't stress enough how this video helped this all finally make sense, just awesome.

[@simpleidea2825]

Even grade 10 students will be able to understand from this video. Hat off 🙏🏻🙏🏻

[@russellsteadele6518]

This is absolutely fantastic as a visualization!

[@-danR]

There's a far better, and even _older_ visualization at: "Radio Antenna Fundumentals Part 1 1947" , KZbin (Fundumentals*) Don't worry about the preliminary part. 16;28 will make the whole business of E and H field propagation crystal-clear, because of the particular visual viewpoint it gives. After seeing that, then I come back to the present video at 5:13 and can now see the point of view they are presenting. ________ *the youtuber's spelling, not the Air Force's

[@rtpfixit]

Perfectly straightforward and clear instructional video. Everything simply broken down to the basics and explained.

[@RosssRoyce]

If it’s clear then why they do show current and voltage both weak at the tips of the antenna? One of these is strong at the tips, don’t you think?

[@aliuyar8537]

The narration level is good for 12 intelligent year old boy. What a success to inform public masses

[@gastongonzalez221]

Wow, the polar diagram explanation starting at around 9:00 minutes blew my mind. Very clear explanation. Thank you.

[@johnishikawa2200]

Good explanation connecting the standing waves of current and voltage to the strength of the magnetic and electric fields that are produced by them, respectively. And an excellent description of how the radiation pattern is sketched by first measuring the field strengths at points away from the antenna.

[@udulamethsara1980]

This is the only one from whole KZbin could explain this perfectly 🎉

[@russ_vee_jr4199]

I just learned more in 12 minutes than I have in the last 50 years. Bravo Canada...........

[@gustavgnoettgen]

If you know about current and electromagnetism already, this is incredibly beautiful. Well made explanation what's going on!

[@frankbaron1608]

for such a short film, this is suprisingly informtive and easy to understand.

[@nivid01]

Very good. Thanks, now I learnt a lot more about antenna theory, but I need to keep learning and put the knowledge into action.

[@johnwest7993]

I spent a couple of weeks with headaches reading various textbooks about this until it all sunk in. This makes it perfectly clear in 12 minutes and 25 seconds, (with the exception of the voltage/current phase relationship of the radiated signal.) The only thing I should point out is something that I originally confused myself about from seeing all those sine waves. The field doesn't actually have the 'shape' of a sine wave. The sine only represents the intensity of the energy and its field polarity reversal. It actually physically 'looks' more like like fluctuating soundwave pressures, (if you can imagine them with 2 phases and a polarity reversal.) Recall that electromagnetic waves have wave/particle duality, so they can also be pictured as a stream of photons of fluctuating density. Good luck with that bit, but you get my point. :)

[@marcv2648]

I think you're wrong about this. Heinrich Hertz showed in the 1880s that radio waves are indeed 2 dimensional waves (transverse waves). Yes this may seem weird when you are forming a mental picture, but it is demonstrably true, and antennas depend upon this 2D physicality. Sound waves are longitudinal waves. They are indeed 3 dimensional.

[@PinkeySuavo]

Yeah I was ALWAYS confused with the sines regarding audio and em waves... The audio I understood by watching shockwaves. So I wanted to imagine EM waves the same. But I don't get this 90 degree between waves. I dont really understand these waves. I feel like I understand magnetic and electric field, but not a wave of them.

[@JenkoRun]

"Recall that electromagnetic waves have wave/particle duality" That's an inherent contradiction.

[@pharmapsychotic]

This video turned my life around.

[@Leela_X]

I tried to understand this many times.... Now I do!

[@companymen42]

I want a refund from my university. My instructor has his PhD in this and still couldn't explain it...

[@owen7185]

Sadly the tale of many universities today

[@bran_rx]

@@owen7185 facts... guy who taught me signals and systems is a fraud lmao

[@owen7185]

@@bran_rx I believe you 💯💯

[@moodflix5053]

🤣🤣

[@youtubeaccount7544]

You’re the one dumb enough to go to “college” for an “education” hahah.

[@naetuir]

This was a great introduction. Thanks for sharing!

[@crazyirishman121]

Amazing animation!

[@kevinrtres]

Brilliant explanation of the basics - thank you.

[@bigmackdombles6348]

this is phenomenal. thank you for posting.

[@mohanjayaraman3291]

Great 👌 Fantastic explanation Thanks to the lecturer

[@jonahansen]

Deusdat - I just received an email where you explained the incongruence regarding the phase of the electric and magnetic field, but it doesn't appear here. But it really does explain it - great thinking, thank you so much. I should have tried to think it through myself - but it needs to be here, so I'm going to copy and paste it from my email: Deusdat replied: My explanation: In fact, the accumulation of electrons at one end of the dipole is caused by the external voltage applied by an electronic amplifier. So it's this electric field that causes the crowding of the electrons, not the opposite. The current produced by these electrons is maximum at the beginning of their flow - and so is the magnetic field! Gradually the accumulation of electrons polarizes the dipole creating a secondary electric field that opposes the initial one. So there is a point when the total electric field is cancelled and the electron accumulation reaches its peak. The current is now zero - and the magnetic field is also zero. Conclusion: both fields are actually in phase, contrary to what is depicted in the video! The phase difference appears between the magnetic field and the polarization of the dipole (the secondary field), not the total electric field. Very well done, dude or dudette, as the case my be!

[@deusdat]

Thanks, I wish I understood other things too. Antennas are a tricky matter.

[@purbeshmitra9704]

That's a good explanation.

[@unclefrankindia]

Great work, simple explanation, had to watch it twice to grasp

[@jagabattunianand1284]

Thank you so much for the video. It really helped me a Lot in understanding fundamentals

[@nathanas64]

What a perfect explanation!!

[@deusdat]

Big flaw: when describing the dipole behavior, H and E are in time quadrature (H is max when E is zero). Later on, when describing the electromagnetic wave, suddenly E and H are in phase. This should have been explained...

[@jonahansen]

Very well said! This is the part that always confuses me, and prevents me from understanding antennas. I've yet to find a good explanation on KZbin. I get that the fields at the antenna are "near field", and the propagating part is "far field", the latter propagating energy independent of the device that launched it. But how does it go from space quadrature to space in-phase?

[@MarcelloZucchi91]

Good observation. The exposition in this video is clearly simplified. In the dipole behaviour, what is shown is only the reactive part of the field, which dominates in the vicinity of the antenna, being the dipole a resonant (reactive) structure. The energy of this field is stored near the antenna and does not propagate. Thus, E and H field are in quadrature. But there is also another contribution, the radiation field, which is smaller but propagates far from the antenna, in which the E and H fields are in phase. If you're familiar with AC circuits, that's exactly the same with voltage and current on a load.

[@jonahansen]

I had to add a separate comment since KZbin is messing up. See it above/below. Thanks - it is excellent...

[@aryamanmishra154]

I observed the same stuff

[@alanmalcheski8882]

watch it again. they say that the dipole antenna creates half a wave, not a full wavelength. It has only the peaks of the waves at each end, but it creates a whole wavelength, when it goes back and forth. The charge in the antenna is bouncing back and forth from right to left and each time it hits the end and bounces back, the wave conforms to the same wave pattern, bouncing energy in each direction equally, but the flow of the EMR is going in mainly only one direction... the radiation is not equal, as you see, it goes more to the right than left, because of the reflectors but also because of how it projects the signal into the air. The signal leaves the antenna as the charge in the dipole hits the end, or reflector, and because of the way the two wave vectors keep things spinning one way, the dipole continues to project the signal in that direction, just weaker as the electrons in it are going backward, in it. That's my first guess. The dipole only needs to create half a wavelength to transmit a full wavelength. But i don't know what a full wavelength making thingy dealy would look like.

[@RemoMass]

Really explained simple to understand, thanks for efforts

[@gnagyusa]

Brilliant explanation.

[@urosmil]

Great video!

[@mailamaila5918]

Great stuff , my cup of tea

[@xichen8267]

Very valuable information!

[@margaretdesser2376]

Great explanation.

[@MeMe-kq5xs]

Please post more videos. Much better explanation with the visualization than traditional textbook

[@anthonywstanton]

Thank you for posting! 73 de AC6GM!

[@EstevanRLima]

Great video

[@Regalert]

Man, old dudes must use 100% mind power and 100% effort, creating such billiant people.

[@samihawasli7408]

Screw it, I’m never calling the right hand rule again. Pun absolutely intended

[@uberdang830]

So the length is related to the frequency range you want to transmit and also the direction of propagation in your antana. You can build a quarter wave dipole that will propagate downward into a ground plane that pushes or reflects them. So you can build a directional antenna. I don't know how this works for a 3/4 wave antenna but. I'm trying to learn.

[@arjunmonga1054]

Amazing

[@user-tn4cf9be8o]

this is phenomenal. thank you for posting.. Really explained simple to understand, thanks for efforts.

[@victorb22622]

Wow,realy very excellent tuition

[@eggxecution]

great explanation

[@albertoolmos21]

The electrons do not flow, the energy wave does. Like water in the sea there's a difference between a sea wave and a sea current. For instance, an anchored boat keeps waving up and down but it is displaced by the current if the anchor is taken. In electricity this is known as displacement current (the actual electron movement from atom to atom which can lead to a different compound [electrolysis]) and conduction (wave) current.

[@ME-rv1pw]

If I can interject here: Electrons do, in fact, flow

[@PinkeySuavo]

soo dont electrons flow? Batteries work by moving charge from one terminal to another one.

[@JenkoRun]

@@PinkeySuavo Charge yes but not Electrons, they barely move and aren't even particles in the first place.

[@lalitthakur1360]

Superb !!

[@emake2394]

Меня всегда вводили в ступор эти картинки, где магнитное поле и электрическое поле находятся на пике. И все, кого не спрашивал просто говорили :. "а что тут непонятного". Хотя сами не понимали моего вопроса. Никто нам не объяснял, как зарождаются волны в антенне. А тут профессор объяснил, что когда электрическое поле на максимуме, то магнитное поле на нуле , и наоборот. В англоязычном интернете больше нужной информации, жалко. Но я рад что прояснил. У нас преподы постоянно пытались спрятаться за сухими формулами и формулировками, вместо того, чтобы объяснить на пальцах.

[@jorgezuni2818]

I’ve only know the sine wave form but never seen anything like this ..More visual dimension trough this video wow

[@HaibatAli]

Best to start, need more vedios on transient radiation from antenna if possible

[@to-tt7fc]

I think any length of the dipole from one end to the other still radiate but full/2 (half) wavelength give you the most and consistent radiation.

[@MarcelloZucchi91]

You're right. Any integer multiple of half wavelength will make the dipole resonate and therefore radiate at its maximum capability.

[@to-tt7fc]

@K8BYP _ you are genius better than Einstein. Your circuit issue is your problem, not anyone else 's fault. Antenna is an integral part of the RF and it does not affect its performance ? Read more on 1/2,1, 1/4 ... wavelength dipole antenna to educate yourself.

[@ryansanderson7023]

@K8BYP _ David, you come across sounding like a jerk here.

[@indridcold8433]

It is sad just how much the education techniques and materials have degraded over the decades. (I think the Roman numeral year, at the end, is 1959) Now, price goes up, content goes down, quality disappears. This video reminds me of why college is such a waste of money today. I even fell for the college lie. It all worked out at the end by getting an unrelated job to what I studied. I am making far more than I could ever have made in the computer field, which is the unfortunate field I studied. None of the content was as methodically explained as this antenna theory. At least I paid my tuition loan in full, using my current job.

[@breakingthemasks]

What kind of job did you get?

[@streaMania]

I think education material should be updated, especially in engineering fields. They are teaching too much irrelevant information.

[@indridcold8433]

@@breakingthemasks I am a glorified grease monkey. I serve, repair, reprogram, hydraulic equipment, lorries, freezers, assembly lines, even the sales fleet vehicles of Estes Logistics. All I do is work with machinery all day. Granted, some of the work is network and computer related. But that is in all fields today. Should I have been a programmer at Blizzard Entertainment, I would max out around 180,000 for the very highest possible pay, which I likely would not have obtained. Today, I make far more than their senior programmers, their IT experts, their hardware engineers, and the such.

[@willson8246]

4:42-4:52 Shows the E field and the H field is 90 degrees out of phase but at 5:54-6:00 when we combine the component of E and H fields together, why both fields are in phase?

[@puchwdface1781]

gothcha *E : 1 0 1 0 1 0* *H : 0 1 0 1 0 1* yet this Video was great thou

[@chancenorris3409]

Was thinking the exact same thing

[@awaludin98]

super awesome

[@satyavanu]

great video

[@arturboras6615]

nearly perfect !

[@burakapaydin9023]

At 4:42 it is said that E-field and H-field are 90 degrees out of phase. Then they end up being in phase. I don't get it. Someone please explain that.

[@swethachilveri4123]

thank you

[@shakiraakbar6072]

Thank you soooooooo much 🙏🙏🙏🙏🙏🙏🙏🙏🙏🙏🙏🙏🙏

[@OviedoSaul]

Awesome

[@vijay0861]

Thank you very much for this video...

[@nebula1100]

This is so intuitive I’m CONVINCED my EE degree was a total scam.

[@MelanieEdgal]

Excellent. I knew nothing about how antennae’s worked and I have a good grasp. I loved the repetition at the end.

[@nobodynowhere7163]

Best electromagnetics course ever.

[@Frohicky1]

I didn't think after that music it could get any better, but it did.

[@COMB0RICO]

Thank you from Texas!

[@roncho]

very nice this record looks very old but animations are great

[@KingsleyIjike]

This is simply awesome! I recommend that students see this video before reading any of those intimidating books! lol

[@RosssRoyce]

In this diagram animation BOTH the VOLTAGE and CURRENT (fields) are drawn as strongest in the middle of the antenna. As far as I know one of them should be stronger at the tips of the antenna and the other weak at the tips but strong at the feed points.

[@edreesalmansoori6051]

Appreciate your time in making the video. Thanks deeply from my heart!

[@northbetrue]

Pro job. Thanks. 73

[@reidshillingburg5658]

I was definitely thinking an episode of Tom and Jerry was about to start after that intro..

[@EvaTruve]

Beautiful! Isn't it!

[@eyalbaum1254]

why did the E vector switched directions when hitting a reflective surface but H didn't?

[@jonahansen]

A reflective surface is one with (ideally == totally reflecting) no resistance, so at the surface the solution to the wave equation, which is the sum of a forward traveling and reverse traveling wave cannot have an electric field (no electric field in a conductor). So to satisfy this boundary condition, the reverse traveling wave must have the opposite electric field so the sum at the surface is always 0. Hence, the exact impinging wave is reflected, inverted in polarity and summing with it. For a sine wave, this implies standing waves starting 1/4 wavelength from the surface and then at 1/2 wavelength intervals with nodes (no electric field ever) at the surface and then again at 1/2 wavelength intervals. Makes sense, eh? The magnetic field must stay the same for the Poynting vector to reverse, which identifies it as reflected, traveling the opposite directing. Just use the right hand rule for E x H for the impinging and reflected to verify this.

[@knife-wieldingspidergod5059]

@@jonahansen My brain just exploded.

[@nithya1747]

@@knife-wieldingspidergod5059 yeah me too

[@-danR]

@@jonahansen This explanation should start on a simpler basis. The reflector an electrical conductor. It is not a magnetic 'conductor' (what would constitute a "magnetic conductor" might be interesting, but needn't detain us here). *The E-field is reversed in polarity by simple counter-EMF, just as it is with any electrical conductor.*

[@tovshows]

Nice thanks : )

[@VR2WAX]

Good sharing! 73 de VR2WAX, over!

[@christopheroptimusprime2631]

Let's watch

[@shanwickramasinhe8270]

Thanks

[@atheistaetherist2747]

The so-called flow of so-called electrons in an antenna or in any wire is a secondary effect. There is a slab of transverse E by H energy current flowing along the outside of the antenna/wire. As explained by Heaviside, Ivor Catt & Forrest Bishop. There is no such thing as charge or voltage. Also, skoolkids should be told that radio waves (ie so-called em waves) are a different animal to photons. And any explanation should involve aether.

[@daviddickey9832]

Wait....at 2:47 are those field lines supposed to be going the other direction by the way the current is travelling and the right hand rule?

[@MateussCelioBR]

The right hand rule uses the conventional current flow, that is opposite the real flow of electrons. In the video, is showed the flow of electrons...

[@MrQuazar]

so how it can be visualisation in 3 demetions? I understand at each point of space there will be changes in the magnetic and electric field vectors according to the wave parameters, but it is difficult to imagine visually other than spherical propagation. We will always be able to see only the projection of a 3-dimensional wave on the 2D plane at each point without being able to appreciate all the beauty. As if in primitive 3D games to save resources some 3D objects are replaced by 2D sprites.

[@ThePtgautam]

Best

[@banjohero1182]

love the needlessly dramatic music on the credits

[@kiranchannayanamath3230]

How E and H fields which are out of phase near the antenna , attain same phase after a certain distance ?

[@rickwest2818]

My question exactly. No explanation anywhere that I've been able to find and I've looked.

[@AdeepaPalihawadana]

Great Video.. but is there a phase difference between E and H fields?

[@KingsleyIjike]

Yes. The E-field leads by 90 degrees

[@georgegillespie1]

In the antenna yes, but in the far field they are in phase.

[@powertube5671]

@@georgegillespie1 That is correct and that is what is misleading about the video. The immediate field or (Near field) is NOT the one that radiates. It is the Far Field and that is produced by ACCELERATING charges (not mentioned). Fields that are 90 degrees out of phase do not transfer power to space. They MUST be in-phase. The radiation phenomenon is left out. The rest of the video is correct.

[@janf.5510]

@@powertube5671 cool! Where can I find more about what you are saying?

[@vaibhavbhasin3861]

Where to find more videos like this ? Completely amazing , plz tell anyone

[@breakingthemasks]

Look for army training videos. There are some good ones frlm is army and navy

[@vaibhavbhasin3861]

@@breakingthemasks thanks

[@breakingthemasks]

@@vaibhavbhasin3861 ... kzbin.info/www/bejne/qWLMXpekdq1sj5Y Etc 👍

[@WR3ND]

1:04 - it should be noted that this visual representation is not a sign wave form but momentary pulses as it does not fade in and out. Indeed, radiating from one point wouldn't have the dynamic of traveling along a radiating element, so that doesn't mean it is necessarily incorrect, just not representative.

[@WR3ND]

1:43 While electrons do move it is not the electrons themselves that are moving this distance but rather their electrical field, similar you could say to how a wave travels across water though the actual specific molecules of water aren't traveling the full length of the wave's propagation.

[@erinlummis7109]

Hi Doug, I was wondering if you knew the date this video was made? Im doing a presentation on animation in the 1950s and would like to use it.

[@Bonkers01]

Hi Erin. archive.org/details/antennafundamentalspropagation Good luck!

[@werre2]

now all it needs is more title screens and dramatic music

[@stevedoe1630]

Does the digital broadcast change this principle at all? (e.g. HD radio, HD tv signal, etc.)

[@Bonkers01]

No. Simply put, The signal is encoded and added to the EM wave and then decoded at the far end.

[@stevedoe1630]

Doug LeBlanc Understand that the signal may be analog or digital, but the frequency (EM wave) carrying the signal stays the same. Thanks.

[@randomdude1053]

Damn as a Canadian signals soldier I never knew we used to make cool videos like this

[@HarryKhan007]

If you build an antenna half the length of a light wave and power it in the classical way by arc, will it send and receive light waves?

[@antonwang120]

what do you mean “arc”?

[@HarryKhan007]

@@antonwang120 Like at welding, or like the first dipole antenna was powered. For 1 micrometer, you need less than 1 Volt to create a sparkover.

[@vahagnmelikyan2906]

Why is the magnetic field coming out from the antenna not even at any point? As far as I know electricity flows evenly in the wire,so why would the center have stronger field than the edges?

[@petertwiss356]

Excellent video, but I think they showed (visualization) the E-field and the H-field in 180degress phase, when he stated 90-degrees.

[@samuelj5890]

look up your angles Pete

[@ThomasHaberkorn]

what's the difference betwwen near field and far field EM-physics?

[@parthenocarpySA]

My marriage was on the brink of collapse before this video cured my wife of wokeism. Thank you so much Canada

[@DominicGo]

this makes me want to take an engineering course

[@eknaap8800]

First learn how to use capitals and proper punctuation...

[@ganeshr3493]

@@eknaap8800 he is not writing an exam here he just wrote a comment.stop banging your english tutor.