I am reminded of one of my biggest aha moments as a child: at a big budget science fair they set up two (now extinct) 8 foot diameter satellite dishes facing each other across an enormous gymnasium, end to end. The receiver had been stripped and in its place was a simple piece of PVC pipe. Now the gymnasium was full of other exhibits, and hundreds of people were wandering around, playing with noisy gadgets, and laughing and talking. It was a cacophony of sound, like you can imagine. One person could stand at a dish at each end and YELL across the room, and the other person simply wouldn't hear it. I doubt even a bullhorn could cut through the din at that distance. HOWEVER! One person puts their ear to a tube, and the other person talks into the other tube, and with a slight delay you can have a clean conversation - and none of the "interference" from the noisy room mattered. Because the dishes were perfectly aligned (like in this video) only the 2 people at the foci were of significance.
They have something like this at Jodrell Bank a large astrophysics centre in the UK, I went there on a school trip many many years back and it's pretty much the same setup, except this is outside and the distance between the two dishes is maybe 200 meters, so cool!
The Oval Office of the White House actually is elliptical, and sounds made at one focus are clearly audible at the other focus. This is clearly intentional, although I'm not entirely sure what purpose it was intended to serve other than being impressive in the days before amplification.
In 2D a circle analogue would just be a line segment blocking the wave. I'm not sure, but I think the center spot would be brighter in 3D than 2D because in 3D the wave would have the entire circumference of the circle to diffract around compared to just the two ends of the line segment in 2D.
It's nice that the simulation also demonstrates signal loss as part of the wave doesn't bounce off the antenna, and how external noise influences the signal quality
Only if the feeder is omnidirectional :) If the feeder is directional and pointed towards the parabolic reflector, all the energy goes reflected to destination. That's why in some broadcast dishes, you find a small reflector in front of the feeder antenna, so to reflect all the signal to the main dish
@@MatteoGalet except that has nothing to do with what the op was commenting about. this was not a demonstration of the situation you described. and so it did infact demonstrate the signal loss.
@@darkracer1252 what he wrote is applicable both in case of the emitted signal (which I commented on), and the received signal. But in the latter, there is HUGE percentage of signal not bouncing off the antenna reflector... Much more than shown in the video
That was the part that interested me the most. I can easily visualize the focusing effect, but seeing how clutter repeatedly interrupted, distorted, and weakened the core signal was fascinating!
See how the primary "flat" wave from the antenna on the left winds up hitting the little dot on the right all at once after it's reflected? That dot's the receiver, meaning it got a vastly more powerful signal than if the transmitter (left dot) had sent the wave in free space without the reflectors. That way transmissions can be sent and received from much greater distances.
@André Bartels You are clearly educated enough to recognize the limits of your knowledge. With a mind open enough to assimilate new information. Congratulations 🎊 👏
You should do one showing waves going through different kinds of filter gates that effect different wavelengths to show the mechanics of hi-pass, lo-pass, noise cancelling, stuff like that.
@@atirutwattanamongkol8806 Signal waves you mean electrical signals? - If so then they are also waves, electromagnetic waves - either in medium or on surface of conductors...
I remember making my first parabolic antenna out of cardstock, glue, and aluminum foil. This was back when wifi routers had external antennas, it would really beef up the signal but it's highly directional.
And this is how we send and receiv information by waves... It is amazing that we can modulate the waves so the signal can transport information in detail to be recgnized and reconstructed on the other side. Science is amazing!
The scale of your colour coding apparently covers an immense dynamic range, because that repeated back-and-forth multiple reflections is never actually seen in practice (at least in radio communications). The dynamic range of radio communications is such that the secondary and tertiary reflections are lost in the thermal noise. If it were not, then the passband would show frequency dependant effects. Thankfully it's not actually a real world thing.
I think the colors cover about 40 to 50 dB. In a couple days there will be a simulation showing a log plot of the energy along a color plot like here, for a different geometry.
@@SimonBuchanNz They're not close !! Based on ~46s travel time at 'c', they're almost 14 million km apart. Of course this implies that they're each about 7 million km in diameter... ;-) !!
@@NilsBerglund Hmmmm... The colour starts out red, and strangely stays red - even as the initial circular wavefront from the feed point spreads out. Just spreading loss alone should have the wavefront changing colour in the first 10s of the video. Perhaps the colour scale has a flat-top section where it's constant colour over at least a magnitude of dynamic range. If the present colour is not log, then it's linear? If it was linear, then it would even more so fade away if the colour scale was distributed linearly. Beware Radio Communications vice Physics (especially Optics), as there can sometimes be confusion and/or miscommunication between 10*Log... and 20*Log... (power density vice field amplitude); almost if they're sometimes speaking a different language. :-)
You're right, I feed the energy into a flattening tanh() function because I don't know the range beforehand. Maybe I should decrease the contrast to get more range, or use a log scale. There will be a log plot for a different geometry in a couple of days.
Kind of like power being generated by the relative motion of conductors and fluxes, produced by the modial interaction of magneto-reluctance and capacitive diractance.
@@silas0403 moreover whenever fluorescence score motion is required it may also be employed in conjunction with a drawn reciprocation Dingle arm to reduce sinusoidal deplanaration. Which, goes without saying, is vital in the operation of Milford trunnions.
@@zombieregime you forgot about the malleable logarithmic casing Because without it the two main spurving bearings wouldn't be in a direct line with the panametric fan.
That's a pretty cool simulation - I like how you can see right where the focal point is and why the feedhorn / sensor sits in that exact position. This is also relevant to how a parabolic microphone would gather and amplify a wave. Great Stuff!
Nice simulation, the best way to experience it is to travel to some place that has an acoustic mirror installed. It is crazy how loud it can get near the focal point of a destination dish.
There's a theme park I used to go to as a kid that has those on either side of this huge hall. You could easily talk to a mate over all the other noise going on, they're proper trippy.
The human brain loves fractal patterns. Clouds, trees, water, moiré, doesn’t matter where it comes from. Fractals are brain food. Or at least yummy spice.
@@AlessioSangalli I would say it's somewhere in between, but mostly due to the size of the mirror and the fact that they diffract the wavefront. 1) There are some artifacts visible, for instance if you look at 0:13 you see that after the reflection on the left parabolic mirror, there are multiple dim circles present. This looks like it's coming from the sharp edges of the pixelated mirror, reflections coming from those should look like light emerging from point sources. It reminds me of the huygens principle stating that any wavefront can be described as the sum of distributed point sources. In our case the distribution is not 100% optimal, otherwise you wouldn't even see any residual circles. 2) The shape you are asking about looks to me like it's the resulting diffraction pattern of the mirror itself. The mirror is finite and the wavefront "sees" this a diffracting object (like an aperture/slit). In the simulation if the size of the mirror was much bigger but with the same curvature you would surely an interference pattern that is a lot less complex. In optics we have to think about this when using a lens to focus a beam. If the lens is too small compared to the beam, the lens will diffract the beam you will not obtain a nice focal spot.
@@mistathenicepersonthatwont2546 received power in milliwatts or dBm. Basically the strength of your signal, think of it like how many "bars" your cell phone has to a tower. Those bars on your phone translate to rssi or rsrq or received signal strength. This visualization shows color range, red meaning strong signal, to green to blue weak signal. The red strength could be something like -50 or better dBM, where the green in the -60's, and blue in the -80's. Closer to 0 is stronger, further from 0 is weaker. Not all wireless is same range. LTE or cell phones, -80 dBm is good, and -120 dBm is poor.
@@Wadmd I work with satellite communication and in our feild -120 is like the silence of space lol. -80 is hardly anything at all if there's something we work within an acceptable range of like -60 up to -5 or -4 depending on whats being measured. Edited for spelling error
Please forgive my ignorance on the subject as I'm brand new. Regarding the part of the initial wave that didn't touch the first parabola, once it arrives at the second parabola (around 0:33) is it received simply as noise? Would the other antenna, generally speaking, have a threshold filter that would filter it out? Thank you for making this.
That part of the wave would be received as a fainter and unfocused version of the signal. The longer the distance between the parabolic reflectors, the fainter this part would be. Real dishes use a directional emitter, to avoid this part of the wave altogether.
This is one of the most beautiful things I have ever laid eyes on. The interference patterns are beyond my conception and cognitive abilities (the maths behind this are astonishingly complicated and could only ever be done with a sophisticated computer algorithm) but I, at least appreciate the work and thought that has gone into this glorious animation. Thank you for the effort you've put into this.
Awesome, better than I hoped! Thank you for all the demonstrations you've been putting up. It's interesting how the wave doesn't seem to do any wrapping around the edges, is that due to them being sharp?
I think so, yes. There should be some diffraction on any edge, but it will depend on the angle at the edge. Also, I lowered the contrast a bit compared to some previous simulations.
I have been interested in point to point microwave for a long time and never has this connected with me in such an intuitive way. the color grading and seeing everything hit the focal point at the receiving end really did it for me.
University Astronomy Professor: Fluid Dynamics in all its magnificent splendor! The applications and implications of this beautiful simulation are Beyond far-reaching!! From the macroscopic universe to the world of quantum mechanics!!
For real, the fact that we can understand something as simple as this is a such a beautiful concept. Hope we all can find peace in our minds with our understanding of the universe.
Explanation: The node where the wave starts is at the parabola’s foci, a specific point where the wave can bounce perfectly to form a straight line coming out. When it hits the other parabola, it bounces directly into the opposite foci.
For anyone wondering, this is why satellite receivers are usually shaped like a shallow bowl. That bit sticking out in the middle is where the magic happens. Do not touch that bit, it gets insanely hot. Now if you want to see something really mind blowing, you should see a cross section of one of those middle bits. Different ones for different wavelengths have different amounts of spacing.
watching this on double speed while super stoned was a visceral experience. the swelling of the music sounded like throat singing to witness the perishing wave
The timings incredible and it's cool how it comes off flat with the curved surface hitting the curved surface and it seems to do something in the exact same spot at the dot on the other side and then it seems to terminate backwards started Pretty cool
I recall at school in science the teacher setting up two parabolas and creating a spark in one with a battery and that spark being copied in the other parabola although there was no power there. This was a great demonstration of how that could refocus the energy of the spark. Of course it is the basis of radio, and these days microwave transmission.
Thank you so much for posting the C code. I've been thinking recently about simulating wave propagation and interference/beam forming from various speaker drivers, while simulating cone break-up in 2D, among other things. Then this video gets randomly suggested... the mind boggles at the algorithm.
You're welcome! Keep in mind I used the simplest possible algorithm, so depending on what you want to simulate, it may be necessary to use an improved version.
@@NilsBerglund Yes, I will probably have to stare blankly at it for some time to even have a faint idea what its doing. Then figure out how to make a rough approximation of a driver...
@@lolerskatez My photographic eye is always looking for simmetries and reflections or for any geometric patterns and textures that can be spotted in natural or less natural landscapes. This is what motivated my comment. I love the human ability of generating works of art, either on purpose or not.
you actually can speed any youtube video to any value up to 16, if you are on computer type Ctrl + Shift + J, in the tab that opened copy and paste document.getElementsByTagName("video")[0].playbackRate = x where x is the speed you want, for example 3, then press enter, you can close the tab and play the video
I had a friend that made these two parabolic antennas in real life (around 2 meters high each) 10 meters from one another. When you whispered towards one of them, the person in the front of the other one could hear what you said. It was amazing and bizarre at the same time.
I think so, although I'm not completely sure. I'm using here a simple discretization on a square grid, which does not fit the parabolas. It would probably be better to use a finite elements discretization adapted to the parabolas, but that would be harder to code...
@@NilsBerglund i actually thought this was a finite element simulation, although the straigt line formed after the first bounce made me doubt it for a bit. This is great!! Thanks a lot!
The placement of the receiver transmitter in the parabolic formula escapes me right now but I completely understand why the emplacement is so important I knew that it worked I didn't know why it worked
A nice idealization of the "near field" solution set. We also see the far field diffraction pattern evolve as the first reflection travelling to the right approaches the right side reflector. I suspect COMSOL or that like was used here, and it is SO effective.
@@NilsBerglund This sounds like an example of an optical resonator. Lots of interesting math and physics to be visualized there with different configurations and stability conditions!
I love the esthetics and the music choice to your videos. I love how much you simplify the understanding of quantum wave to quite comprehensive animations. I imagine it takes quite a bit of effort for the code to work out. Your chanell could be used as an good example, and explantion in quite a few Univerities. I have a question for you tho: 1.Are you maybe planing to expand to 3D at some point? 2.Can you make a "presentation" on polarization? Keep up the good work, sadly your chanell is quite a nieche...
Thanks! Feel free to recommend this channel to any math/physics teachers/professors you think may be interested... 1. Solving real 3d wave equations would take too long at this point, roughly 1000 times longer to compute. What seems possible is to do 3d plots of the 2d wave equation, that is, the wave height z as a function of x and y. I'll have to refresh my knowledge of 3d OpenGL, though. 2. I'll have to look into what could be interesting and possible to do with polarization. I assume it would require a vectorial, 2d wave equation, e.g. a version of Maxwell's equations.
@@NilsBerglund I was thinking abbout that 3d thing. I'm no quantum scientist, nor programmer. BUT I was thinking about making two separate animations one for vertical axis, and one for horizontal. It seems like you could "hide" some of the data in the colour values, and maybe it would be possible to make the whole thing using just two separate animations... you would have to have some kind of dedicated compiler of some sorts to transpose the data to 3d... It propabbly would work if you would stick to "simple shapes" like well parabolic mirrors for example :x ... spheres, walls, cubes etc... like I said I'm no computer scientist but maybe some kind of X-Y axis shenanigans is possible if you could menage to use the colour values as some kind of medium, and since you already use it to represent the strength, phases, and other values... maybe that ain't that far off... dunno just thinking out loud :) Have a nice day and please do continue your good work
A really cool add-on calculation for simulation is: the wave decay from opposing waves passing through each other... To show the resistance & acceleration factors that shape the focal point
in the 1980's I went to a science exhibit at Balboa Park. There were tons of interactive displays and one of them consisted of 2 huge parabolic dishes mounted on walls about 50 yards apart. If you spoke facing one of the dishes your voice could be clearly heard on the other side of the room. It was very cool.
If you’ve ever been to the NEMO science museum in Amsterdam, The Netherlands, you may have seen this one thing where there are two concave shapes facing each other with a small-ish ring in front of each one, if a person sits in front of each one and places their head in the ring, when one person says something, the other one can hear them quite clearly, as if they are only a few feet away, mind you, these things are around 50+ feet apart, turns out those concave shapes are actually parabolas, and the rings sit in the focal points, this video shows very well what the sound is doing
from one professional to another, looks awesome, saw some grid artifacts at early times i.e. the initial spherical pulse isn't symmetric, loved how the pattern evolves and gives a sense of where the light goes in all of time and space :)
Many thanks! When I started making these simulations of the wave equation, I did not have much experience with hyperbolic PDEs, being more used to elliptic ones. So I'm glad if experts approve :)
Your simulation results are really interesting. I’d be quite interested to see similar images for a microwave cavity resonator field as I’ve long tried to visualize such. Thanks much!
Thanks! While I have not simulated microwave cavities as such, I have several sims of "parabolic resonators" that may interest you, they are in the playlist ua-cam.com/play/PLAZp3rbgWLo3VO2rqVKyL1T6DUmnDAaEN.html
After watching this i think that i now realize why most satellite dishes are parabolic. The dots near each antenna to me represent the receiver module as most of the energy gets reflected through one of the two points once it bounces off the antenna behind said point. Amazing simulation btw
idk why this showed up in my recommended but it just made me realize how we're able to pick up and send signals from and to spacecraft located as far away as the edge of the solar system. The beams spread out by the time they get to their destination, but you don't need to capture all of the radio waves to interpret the data, only a small portion. As long as the wave wasn't distorted too badly, the sequence of the bits will be preserved.
The first reflection gives a fairly coherent straight line segment. Unfortunately, pretty soon after the second reflection, the only visible effects are effects of the ends of the reflectors, i.e. the parts which are not parabolic.
For the pattern to repeat, one needs to put the reflectors closer to each other, so that they share their focal point: ua-cam.com/video/n19XjuK_Dgs/v-deo.html
So cool too see how the waves don't bump into each other, they just pass right through each other yet they can cancel each other out like waves in a jump rope.
It was interesting that the left antenna reflected the circular wave into a flat one, but the right antenna did not flatten the curve because it traveled farther and lost some of its curvature due to the increased radius.
What is the shape of the pulse in the time domain? Back in the nineties I did a simulation of the acoustic scattering from a rigid sphere, showing what happens when it is hit by the spherical wave emitted by a monopole source. After much experimentation I settled on a Hanning pulse as input to the monopole source. The main energy content was concentrated below 3kHz. It took ages to make the animations but they served us well. We had them put on to VHS tape (no s***, we even had a version in the format used in the US) and showed them at conferences around the world!
It's so interesting how the waves interact around the "trasmitter" or "receiver" part, idk what its called. whatever it's called, it's in the perfect focused spot. The math behind that precision is so interesting. People are capable of some really fascinating stuff.
this makes so much more sense now! in my city there’s an exhibit in a part where there’s 2 dishes far away from each other, but when you talk into them you can hear the other person very clearly, even if you whisper!
My school had a couple parabolic dishes on the roof specifically as a physical demonstration of doing this with sound. You could talk to the person at the other dish across the roof as if they were right next to you.
I NEED my advanced antenna engineering lectures to start as soon as possible. After RF circuits and microwaves I really want to understand how antennas work!
I am reminded of one of my biggest aha moments as a child: at a big budget science fair they set up two (now extinct) 8 foot diameter satellite dishes facing each other across an enormous gymnasium, end to end.
The receiver had been stripped and in its place was a simple piece of PVC pipe.
Now the gymnasium was full of other exhibits, and hundreds of people were wandering around, playing with noisy gadgets, and laughing and talking. It was a cacophony of sound, like you can imagine. One person could stand at a dish at each end and YELL across the room, and the other person simply wouldn't hear it. I doubt even a bullhorn could cut through the din at that distance.
HOWEVER! One person puts their ear to a tube, and the other person talks into the other tube, and with a slight delay you can have a clean conversation - and none of the "interference" from the noisy room mattered. Because the dishes were perfectly aligned (like in this video) only the 2 people at the foci were of significance.
that's so cool
Thats awesome
They have something like this at Jodrell Bank a large astrophysics centre in the UK, I went there on a school trip many many years back and it's pretty much the same setup, except this is outside and the distance between the two dishes is maybe 200 meters, so cool!
The Oval Office of the White House actually is elliptical, and sounds made at one focus are clearly audible at the other focus. This is clearly intentional, although I'm not entirely sure what purpose it was intended to serve other than being impressive in the days before amplification.
@@mal2ksc You think that would be intentional? Seems a bit of a security risk. *Whispers quietly to veep.
Guy on other end: "I can hear you..."
I’m now gonna call parenthesis “parabolic antennas”
I don't know why but your comment made me laugh really hard brah
I'm now going to call curved brackets as "parenthesis".
@@onepunchman1953 lmao
Hark, what men are these, that wear their legs in parentheses. 🙂
Antennae are for animals, antennas are for communication
Wave around a circle to show that the brightest point in a Shadow Is the centre
Thanks, I'll have to see if I can find parameter values allowing to demonstrate that...
@@NilsBerglund That'd be awesome
@@NilsBerglund It would be awesome
In 2D a circle analogue would just be a line segment blocking the wave. I'm not sure, but I think the center spot would be brighter in 3D than 2D because in 3D the wave would have the entire circumference of the circle to diffract around compared to just the two ends of the line segment in 2D.
You notice that if you have more than 2iq
It's nice that the simulation also demonstrates signal loss as part of the wave doesn't bounce off the antenna, and how external noise influences the signal quality
Only if the feeder is omnidirectional :)
If the feeder is directional and pointed towards the parabolic reflector, all the energy goes reflected to destination.
That's why in some broadcast dishes, you find a small reflector in front of the feeder antenna, so to reflect all the signal to the main dish
I thought the same one 👍
@@MatteoGalet
except that has nothing to do with what the op was commenting about.
this was not a demonstration of the situation you described. and so it did infact demonstrate the signal loss.
@@darkracer1252 what he wrote is applicable both in case of the emitted signal (which I commented on), and the received signal.
But in the latter, there is HUGE percentage of signal not bouncing off the antenna reflector... Much more than shown in the video
That was the part that interested me the most. I can easily visualize the focusing effect, but seeing how clutter repeatedly interrupted, distorted, and weakened the core signal was fascinating!
It shows really nicely how parabolic antennas keep a signal crisp between the antennas focal points.
It looks like a little ray gun shooting a beam directly at the foci
I don't have the education to see the benefits of this simulation, but it is beautiful.
See how the primary "flat" wave from the antenna on the left winds up hitting the little dot on the right all at once after it's reflected? That dot's the receiver, meaning it got a vastly more powerful signal than if the transmitter (left dot) had sent the wave in free space without the reflectors. That way transmissions can be sent and received from much greater distances.
Bro easily I can beat you in a foot race to 20 yards.
@André Bartels You are clearly educated enough to recognize the limits of your knowledge. With a mind open enough to assimilate new information. Congratulations 🎊 👏
@@ToastyMozart this is also how brittain made theyre first Way of detecting german bombers
@@fregtz735 those big ass antenas that would pick up the sound of i coming bombers?? Is that what you meant
truly one of the best uses of three minutes ever
You should do one showing waves going through different kinds of filter gates that effect different wavelengths to show the mechanics of hi-pass, lo-pass, noise cancelling, stuff like that.
you know those are different waves, right? Those filters deal with waves as a signal, not as physical waves.
@@atirutwattanamongkol8806 signal waves are physical waves.
@@MrMegaMetroid No? Physical waves travel through the air in 3d but signal waves are just fluctuations in the current
@@atirutwattanamongkol8806 Signal waves you mean electrical signals? - If so then they are also waves, electromagnetic waves - either in medium or on surface of conductors...
Are there physical filters? Or do you mean the ones we do with electronic components?
I remember making my first parabolic antenna out of cardstock, glue, and aluminum foil. This was back when wifi routers had external antennas, it would really beef up the signal but it's highly directional.
Aw the old pringle can days.
And this is how we send and receiv information by waves... It is amazing that we can modulate the waves so the signal can transport information in detail to be recgnized and reconstructed on the other side. Science is amazing!
The scale of your colour coding apparently covers an immense dynamic range, because that repeated back-and-forth multiple reflections is never actually seen in practice (at least in radio communications). The dynamic range of radio communications is such that the secondary and tertiary reflections are lost in the thermal noise. If it were not, then the passband would show frequency dependant effects. Thankfully it's not actually a real world thing.
I think the colors cover about 40 to 50 dB. In a couple days there will be a simulation showing a log plot of the energy along a color plot like here, for a different geometry.
I wouldn't be surprised to see the effects shown when the antennae are this close?
@@SimonBuchanNz They're not close !! Based on ~46s travel time at 'c', they're almost 14 million km apart. Of course this implies that they're each about 7 million km in diameter... ;-) !!
@@NilsBerglund Hmmmm... The colour starts out red, and strangely stays red - even as the initial circular wavefront from the feed point spreads out. Just spreading loss alone should have the wavefront changing colour in the first 10s of the video. Perhaps the colour scale has a flat-top section where it's constant colour over at least a magnitude of dynamic range.
If the present colour is not log, then it's linear? If it was linear, then it would even more so fade away if the colour scale was distributed linearly.
Beware Radio Communications vice Physics (especially Optics), as there can sometimes be confusion and/or miscommunication between 10*Log... and 20*Log... (power density vice field amplitude); almost if they're sometimes speaking a different language. :-)
You're right, I feed the energy into a flattening tanh() function because I don't know the range beforehand. Maybe I should decrease the contrast to get more range, or use a log scale. There will be a log plot for a different geometry in a couple of days.
That's really cool. The refraction pattern is like watching a macro scale double slit experiment.
Kind of like power being generated by the relative motion of conductors and fluxes, produced by the modial interaction of magneto-reluctance and capacitive diractance.
@@Synthwave89 Exactly! Gotta be careful though to prevent side-fumbling of the unsynchronised gramm-meter..
@@silas0403 moreover whenever fluorescence score motion is required it may also be employed in conjunction with a drawn reciprocation Dingle arm to reduce sinusoidal deplanaration.
Which, goes without saying, is vital in the operation of Milford trunnions.
@@zombieregime you forgot about the malleable logarithmic casing Because without it the two main spurving bearings wouldn't be in a direct line with the panametric fan.
Ya what he said in ten years when I understand it
2:19 put it on x2 speed and the music becomes drum and bass
That's a pretty cool simulation - I like how you can see right where the focal point is and why the feedhorn / sensor sits in that exact position. This is also relevant to how a parabolic microphone would gather and amplify a wave. Great Stuff!
Thank you very much! You may want to check out the new version ua-cam.com/video/PpKqNk_G2Hw/v-deo.html as well
If you put play back speed to 2x and skip to 2:30 the music is absolutely fire
Nice simulation, the best way to experience it is to travel to some place that has an acoustic mirror installed. It is crazy how loud it can get near the focal point of a destination dish.
Thanks! You also have that in some old buildings, such as the dome of St-Paul's cathedral in London, UK.
There's a theme park I used to go to as a kid that has those on either side of this huge hall. You could easily talk to a mate over all the other noise going on, they're proper trippy.
There is a set of parabolic acoustic reflectors on the side of a large hill at the space museum in Alamogordo NM. Surprisingly effective.
They are a lot of fun. I've never seen a good visualization of it before!
Science works melbourne has this very cool you can almost whisper into the dish and you mate on the other side hears it clear as a bell
Thought this was a Bill Wurtz video when I clicked on it
Still enjoyed it!
( )
My thoughts exactly lmao
Same lol
YES me too
Idk there is something so iconic on Bill wurtz style
a lot more beautiful than I was expecting. The interference pattern at 1:50 almost looks like some sort of plant growing
Wow yes
Is that actual interference pattern or an artifact of the simulation?
The human brain loves fractal patterns. Clouds, trees, water, moiré, doesn’t matter where it comes from. Fractals are brain food. Or at least yummy spice.
@@AlessioSangalli I would say it's somewhere in between, but mostly due to the size of the mirror and the fact that they diffract the wavefront.
1) There are some artifacts visible, for instance if you look at 0:13 you see that after the reflection on the left parabolic mirror, there are multiple dim circles present. This looks like it's coming from the sharp edges of the pixelated mirror, reflections coming from those should look like light emerging from point sources. It reminds me of the huygens principle stating that any wavefront can be described as the sum of distributed point sources. In our case the distribution is not 100% optimal, otherwise you wouldn't even see any residual circles.
2) The shape you are asking about looks to me like it's the resulting diffraction pattern of the mirror itself. The mirror is finite and the wavefront "sees" this a diffracting object (like an aperture/slit). In the simulation if the size of the mirror was much bigger but with the same curvature you would surely an interference pattern that is a lot less complex. In optics we have to think about this when using a lens to focus a beam. If the lens is too small compared to the beam, the lens will diffract the beam you will not obtain a nice focal spot.
At the two minute mark It kind of looks like the interference pattern seen in the double slit experiment.
Writing fea code for over 25 years for magnetics, I've never seen anything so beautiful. Thank you for the great work.
Seeing how messy that is gives me a new appreciation for what radio engineers have to deal with.
Messy but also controlled and predictable
very well structured
Would love to see a graph of the received power over time alongside it
what power
@@mistathenicepersonthatwont2546 received power in milliwatts or dBm. Basically the strength of your signal, think of it like how many "bars" your cell phone has to a tower. Those bars on your phone translate to rssi or rsrq or received signal strength. This visualization shows color range, red meaning strong signal, to green to blue weak signal. The red strength could be something like -50 or better dBM, where the green in the -60's, and blue in the -80's. Closer to 0 is stronger, further from 0 is weaker. Not all wireless is same range. LTE or cell phones, -80 dBm is good, and -120 dBm is poor.
@@Wadmd bro its me downloading 1 megabyte of big chungus meme
@@mistathenicepersonthatwont2546 lmfao
@@Wadmd I work with satellite communication and in our feild -120 is like the silence of space lol. -80 is hardly anything at all if there's something we work within an acceptable range of like -60 up to -5 or -4 depending on whats being measured.
Edited for spelling error
I never heard parentheses be called something as fancy as _parabolic antenna._
I never heard brackets being called something as fancy as parentheses
@@lucasc5622 I never heard curve bois be called anything as fancy as brackets.
@@WiseMasterNinja sideway eyebrows
@@WiseMasterNinja I never heard lines be called as fancy as curvy bois.
@@WiseMasterNinja I've never heard "c" be called something as fancy as curved bois.
Definitely my favorite one so far!
Yay! Thank you!
Please forgive my ignorance on the subject as I'm brand new. Regarding the part of the initial wave that didn't touch the first parabola, once it arrives at the second parabola (around 0:33) is it received simply as noise? Would the other antenna, generally speaking, have a threshold filter that would filter it out? Thank you for making this.
That part of the wave would be received as a fainter and unfocused version of the signal. The longer the distance between the parabolic reflectors, the fainter this part would be. Real dishes use a directional emitter, to avoid this part of the wave altogether.
@@NilsBerglundthank you so much for the reply. That's extremely helpful. I really enjoyed your video. Have a great day!
This is one of the most beautiful things I have ever laid eyes on. The interference patterns are beyond my conception and cognitive abilities (the maths behind this are astonishingly complicated and could only ever be done with a sophisticated computer algorithm) but I, at least appreciate the work and thought that has gone into this glorious animation.
Thank you for the effort you've put into this.
Awesome, better than I hoped! Thank you for all the demonstrations you've been putting up.
It's interesting how the wave doesn't seem to do any wrapping around the edges, is that due to them being sharp?
I think so, yes. There should be some diffraction on any edge, but it will depend on the angle at the edge. Also, I lowered the contrast a bit compared to some previous simulations.
Radio engineers sometimes use the edge effect to diffract radio signals to the other side of mountains.
I have been interested in point to point microwave for a long time and never has this connected with me in such an intuitive way. the color grading and seeing everything hit the focal point at the receiving end really did it for me.
and in phase too!
University Astronomy Professor: Fluid Dynamics in all its magnificent splendor!
The applications and implications of this beautiful simulation are Beyond far-reaching!! From the macroscopic universe to the world of quantum mechanics!!
I did not expect what I saw. Really thought-provoking video!
Those two focal points on each side of the parabolic antennas make it for a richer experience. Brilliant.
This is hypnotic ! Thank you ! I want to see it in a ten-hour looped version !
Maybe one day!
No you dont
For real, the fact that we can understand something as simple as this is a such a beautiful concept. Hope we all can find peace in our minds with our understanding of the universe.
The music makes me feel like the king of the world.
Explanation: The node where the wave starts is at the parabola’s foci, a specific point where the wave can bounce perfectly to form a straight line coming out. When it hits the other parabola, it bounces directly into the opposite foci.
Beautiful demonstration of the effectiveness of parabolic reflectors with recievers/transmitters
These animations have something so soothing and satisfying 💕
For anyone wondering, this is why satellite receivers are usually shaped like a shallow bowl. That bit sticking out in the middle is where the magic happens. Do not touch that bit, it gets insanely hot. Now if you want to see something really mind blowing, you should see a cross section of one of those middle bits. Different ones for different wavelengths have different amounts of spacing.
watching this on double speed while super stoned was a visceral experience. the swelling of the music sounded like throat singing to witness the perishing wave
This video needs 5x to 10x speed.
@@Linuxdirk you can go up to 16x on UA-cam.
@@islandcave8738 It shows 2x as maximum speed here.
The timings incredible and it's cool how it comes off flat with the curved surface hitting the curved surface and it seems to do something in the exact same spot at the dot on the other side and then it seems to terminate backwards started
Pretty cool
I recall at school in science the teacher setting up two parabolas and creating a spark in one with a battery and that spark being copied in the other parabola although there was no power there. This was a great demonstration of how that could refocus the energy of the spark. Of course it is the basis of radio, and these days microwave transmission.
Thank you so much for posting the C code. I've been thinking recently about simulating wave propagation and interference/beam forming from various speaker drivers, while simulating cone break-up in 2D, among other things. Then this video gets randomly suggested... the mind boggles at the algorithm.
You're welcome! Keep in mind I used the simplest possible algorithm, so depending on what you want to simulate, it may be necessary to use an improved version.
@@NilsBerglund Yes, I will probably have to stare blankly at it for some time to even have a faint idea what its doing. Then figure out how to make a rough approximation of a driver...
I love how the waves get the smallest exactly at the focus of the antennas
From the thumbnail, I thought there was a new Bill Wurtz video
This is actually very helpful for better understanding of radio waves. I would absolutely love to see more on the topic
There are many more like this in the playlist ua-cam.com/play/PLAZp3rbgWLo3VO2rqVKyL1T6DUmnDAaEN.html
This is an excellent visualization. That got a subscribe. Thank you.
From a different point of view, this video is a remarkalble proof of how science and digital art can coexist.
Is there a suggestion that they couldn't or don't already?
@@lolerskatez My photographic eye is always looking for simmetries and reflections or for any geometric patterns and textures that can be spotted in natural or less natural landscapes. This is what motivated my comment. I love the human ability of generating works of art, either on purpose or not.
me when i am a wave and i'm travelling between 2 parabolic antennas
This is one of those videos you wish they had 3x speed for.
you actually can speed any youtube video to any value up to 16, if you are on computer type Ctrl + Shift + J, in the tab that opened copy and paste document.getElementsByTagName("video")[0].playbackRate = x where x is the speed you want, for example 3, then press enter, you can close the tab and play the video
@@Rafael-pi4md *cries in mobile app*
@@LonnyH just press the 3 dots
I had a friend that made these two parabolic antennas in real life (around 2 meters high each) 10 meters from one another. When you whispered towards one of them, the person in the front of the other one could hear what you said. It was amazing and bizarre at the same time.
should some of the reflecting waves be cancelled out and/or bifurcate ? (1:30 onwards )
Is the light-blue trailing pattern at ~0.15 s due to interference from the distcretized parabolic surface?
I think so, although I'm not completely sure. I'm using here a simple discretization on a square grid, which does not fit the parabolas. It would probably be better to use a finite elements discretization adapted to the parabolas, but that would be harder to code...
@@NilsBerglund i actually thought this was a finite element simulation, although the straigt line formed after the first bounce made me doubt it for a bit. This is great!! Thanks a lot!
I just wonder what will happened if you have this same configuration, but antennas are closer and shares same focus point.
See my reply to Kram1032.
Damn, I wish we had graphics like this back in the '60's when I was doing acid...
The placement of the receiver transmitter in the parabolic formula escapes me right now but I completely understand why the emplacement is so important I knew that it worked I didn't know why it worked
This particular point is known as the focal point, or focus of the parabola.
A nice idealization of the "near field" solution set. We also see the far field diffraction pattern evolve as the first reflection travelling to the right approaches the right side reflector. I suspect COMSOL or that like was used here, and it is SO effective.
Thanks. The simulation software is my own creation, though: github.com/nilsberglund-orleans/UA-cam-simulations
Funny how it looks like an eye from different perspectives at different times.
what if the two mirrors share a focal point?
Then the wave should keep alternating between planar and circular. It could be fun to try it, thanks!
@@NilsBerglund This sounds like an example of an optical resonator. Lots of interesting math and physics to be visualized there with different configurations and stability conditions!
If the wave origin was also the focal point would it not have destructive interference with itself after the first reflection?
I love the esthetics and the music choice to your videos. I love how much you simplify the understanding of quantum wave to quite comprehensive animations. I imagine it takes quite a bit of effort for the code to work out. Your chanell could be used as an good example, and explantion in quite a few Univerities.
I have a question for you tho:
1.Are you maybe planing to expand to 3D at some point?
2.Can you make a "presentation" on polarization?
Keep up the good work, sadly your chanell is quite a nieche...
Thanks! Feel free to recommend this channel to any math/physics teachers/professors you think may be interested...
1. Solving real 3d wave equations would take too long at this point, roughly 1000 times longer to compute. What seems possible is to do 3d plots of the 2d wave equation, that is, the wave height z as a function of x and y. I'll have to refresh my knowledge of 3d OpenGL, though.
2. I'll have to look into what could be interesting and possible to do with polarization. I assume it would require a vectorial, 2d wave equation, e.g. a version of Maxwell's equations.
@@NilsBerglund I was thinking abbout that 3d thing. I'm no quantum scientist, nor programmer. BUT I was thinking about making two separate animations one for vertical axis, and one for horizontal. It seems like you could "hide" some of the data in the colour values, and maybe it would be possible to make the whole thing using just two separate animations... you would have to have some kind of dedicated compiler of some sorts to transpose the data to 3d...
It propabbly would work if you would stick to "simple shapes" like well parabolic mirrors for example :x ... spheres, walls, cubes etc... like I said I'm no computer scientist but maybe some kind of X-Y axis shenanigans is possible if you could menage to use the colour values as some kind of medium, and since you already use it to represent the strength, phases, and other values... maybe that ain't that far off... dunno just thinking out loud :)
Have a nice day and please do continue your good work
@@NilsBerglund Oh and also, a "time took to render" could be a nice touch for US THE INTERNET NERDS 🤓
Okay, I'll try doing it in future simulations!
It is striking and beautiful to see the waves focus on the receiver antennas like that.
Awesome! It shows why the dot with the sensor in front of both dishes is SO important.
This video is so motivational and inspiring
lol
Me to my gf: what you want??
Her: 0:12
1:05 it’s Wednesday my dudes.
Indeed it is
it's saturday
It's Sunday
2024 on a Wednesday
Best screen saver ever
A really cool add-on calculation for simulation is: the wave decay from opposing waves passing through each other... To show the resistance & acceleration factors that shape the focal point
I felt like god was going to show his face...
( 🌊 )
This actually cleared a few things up for me, thank you.
Glad it helped!
in the 1980's I went to a science exhibit at Balboa Park. There were tons of interactive displays and one of them consisted of 2 huge parabolic dishes mounted on walls about 50 yards apart. If you spoke facing one of the dishes your voice could be clearly heard on the other side of the room. It was very cool.
If you’ve ever been to the NEMO science museum in Amsterdam, The Netherlands, you may have seen this one thing where there are two concave shapes facing each other with a small-ish ring in front of each one, if a person sits in front of each one and places their head in the ring, when one person says something, the other one can hear them quite clearly, as if they are only a few feet away, mind you, these things are around 50+ feet apart, turns out those concave shapes are actually parabolas, and the rings sit in the focal points, this video shows very well what the sound is doing
As a student who never listen and gets bored in science class, just watching this made me question my existence. Its too beautiful
Oh you sneaky B. I just thought I was clicking on a Tom Scott video because of your red shirt in the profile picture xD
What’s the medium here?
It can be several kinds of medium, but is most realistic for sound (pressure) waves in air.
Am I supposed to be cheering for something like this the way I am right now?
A lovely demonstration of focus, dispersion and attenuation.
from one professional to another, looks awesome, saw some grid artifacts at early times i.e. the initial spherical pulse isn't symmetric, loved how the pattern evolves and gives a sense of where the light goes in all of time and space :)
Many thanks! When I started making these simulations of the wave equation, I did not have much experience with hyperbolic PDEs, being more used to elliptic ones. So I'm glad if experts approve :)
Changed my life forever.
This is like one of those things I see when I'm sleep-deprived and hallucinating in a dark room.
Your simulation results are really interesting. I’d be quite interested to see similar images for a microwave cavity resonator field as I’ve long tried to visualize such. Thanks much!
Thanks! While I have not simulated microwave cavities as such, I have several sims of "parabolic resonators" that may interest you, they are in the playlist
ua-cam.com/play/PLAZp3rbgWLo3VO2rqVKyL1T6DUmnDAaEN.html
After watching this i think that i now realize why most satellite dishes are parabolic. The dots near each antenna to me represent the receiver module as most of the energy gets reflected through one of the two points once it bounces off the antenna behind said point. Amazing simulation btw
Thanks. This is indeed precisely the role of the focal points.
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so cool. I have stood at the receiving end of a parabolic antenna and it is unreal the smallest sounds from a large distance that you can hear clearly
idk why this showed up in my recommended but it just made me realize how we're able to pick up and send signals from and to spacecraft located as far away as the edge of the solar system. The beams spread out by the time they get to their destination, but you don't need to capture all of the radio waves to interpret the data, only a small portion. As long as the wave wasn't distorted too badly, the sequence of the bits will be preserved.
The first reflection gives a fairly coherent straight line segment. Unfortunately, pretty soon after the second reflection, the only visible effects are effects of the ends of the reflectors, i.e. the parts which are not parabolic.
For the pattern to repeat, one needs to put the reflectors closer to each other, so that they share their focal point: ua-cam.com/video/n19XjuK_Dgs/v-deo.html
never Admired my calculus lessons related to focal point of parabola until my teacher explained its usage in dish antenas.
So cool too see how the waves don't bump into each other, they just pass right through each other yet they can cancel each other out like waves in a jump rope.
Very cool! Did a simulation of GPR in college bouncing off an object in a medium and could see the evanescent waves in the simulation.
It was interesting that the left antenna reflected the circular wave into a flat one, but the right antenna did not flatten the curve because it traveled farther and lost some of its curvature due to the increased radius.
This is all I needed to understand how point to point antenas work, thanks 👍🙏
You're welcome!
That's a LDE. Long Delay Echos are pretty sweet.
I remember in school when they would draw a parabolic curve and these perfect reflection lines.
What is the shape of the pulse in the time domain? Back in the nineties I did a simulation of the acoustic scattering from a rigid sphere, showing what happens when it is hit by the spherical wave emitted by a monopole source. After much experimentation I settled on a Hanning pulse as input to the monopole source. The main energy content was concentrated below 3kHz. It took ages to make the animations but they served us well. We had them put on to VHS tape (no s***, we even had a version in the format used in the US) and showed them at conferences around the world!
The initial state is radial, with a radial dependence given by a Gaussian times a cosine. I have not tried using a Hanning pulse.
Electrodynamic simulations are hard af. Props man.
Thx!
This is incredible. Wow. And beautiful. Thank you.
Thank you too!
It's so interesting how the waves interact around the "trasmitter" or "receiver" part, idk what its called. whatever it's called, it's in the perfect focused spot. The math behind that precision is so interesting. People are capable of some really fascinating stuff.
this makes so much more sense now! in my city there’s an exhibit in a part where there’s 2 dishes far away from each other, but when you talk into them you can hear the other person very clearly, even if you whisper!
Yes, these kinds of demonstrations are always impressive!
Woah, I want this on a T-shirt!
My school had a couple parabolic dishes on the roof specifically as a physical demonstration of doing this with sound. You could talk to the person at the other dish across the roof as if they were right next to you.
I NEED my advanced antenna engineering lectures to start as soon as possible. After RF circuits and microwaves I really want to understand how antennas work!
Hi! Thanks for posting this. Great concept for a UA-cam channel.