I wrote over 20 papers on metamaterials 18 years ago, and then switched my career to teaching maths and engineering to teenagers. I am still very interested in the research of metamaterials and after following your lectures in the past six years you have helped me make sense of the theoretical understanding of some crucial parameters. I wish I had those understanding 18 years ago when I had more time to consolidate the knowledge and practise it. Please continue to share your lessons or lectures, because it is making an impact for people like me who are still trying to understand metamaterials properties. Your delivery approach is very unique and accessible for beginner level into the subject, and not limited to MIT boffins.
Thank you! You have made my day!!! My metamaterials information is quite old now. I have learned more and better graphics skills. I need to redo and improve those materials! I am curious what you researched.
@@empossible1577 I researched on reduced sized unit cell elements. I thought by increasing capacitance and inductance of a single unit cell would reduce the resonance frequency or band gap frequency, so I applied Hilbert curves and convoluted elements while still keeping the vias. I then assisted in the practical development of wire medium.
@@sbu6thengineering At that scale, coupling short circuits the elements. I think that is why ideas like fractal antennas fall short of what we think should be possible. We are working on using the dielectric to effectively stretch space (think transformation optics) to reduce the mutual coupling in fractal-ish designs. So far, the idea has failed miserably. LOL
@@empossible1577 What frequency are you testing your ideas? While I love to endure THz and upwards as it seems is a trendy thing to do, I simply preferred 60GHz or lower to avoid plasmonic territories which is an area I don't have the capacity for. Also, imaging me going to my school headteacher asking for a funding for a 2nd hand THz VNA of USD 90000 for our 16 to 18 years old school projects, he must think I am having a laugh. As I don't have an anechoic chamber, much of my work now is mainly CST simulation and S11 measurement up to 6GHz. I get the teenage students to model antenna and unit cell on CST. They measure the bandgap frequency using two monopole antenna edge to edge of a 2D metasurface, I prefer the term high impedance surfaces back in Sievenpiper's days. I used to use FR4, now I get my students to 3D print the substrate using PLA filament of epsilon 2.2 to 2.9 depending the infill settings. I am having fun to try and develop metamaterials using standard classroom machines as I don't have hundreds of thousands of dollars funding, instead I get USD3000 school budget to spend on teaching consumables. I am working on developing a small size near field to far field computer controlled system using some left over stepping motors from an obsolete 3D printer. Do you have a working measurement setup to detect band gap of 2D or 3D metamaterial?
Dear Professor, I think there is a slight mistake in the animation where the speed and wavelength change (around 9 minutes). Since the refractive index of medium 2 is higher than medium 2, the speed of the wave in medium 2 should be less, in that case the wavelength should increase instead of decreasing, since the frequency remains constant. Please correct me if I am wrong. Best regards, Arnab
The speed v, frequency f, and wavelength lam are related through v = f * lam Based on this, speed and wavelength will either both increase or both decrease. They will not do opposite things as frequency is changed. I tend to think of the frequency as how fast the wave at a fixed point is moving up and down. If the wave is travelling slower, the wave does not travel as far before the wave cycles. This places the peaks and valleys at closer points (i.e. short wavelength). Give this some thought until it becomes intuitive. Thank you for pointing out a potential mistake!
@@empossible1577 Dear professor. I understood my mistake that day itself but I forgot to delete my comment. It was a very silly mistake of understanding on my part, I am so sorry. I think of it now in this way, the wave will travel the maximum distance (max wavelength) in a medium where the speed is the fastest, that is in vacuum (well, technically vacuum itself is not a medium), the wave travels 3*10^8 meters in 1 second. In any other medium, the wave will have less speed, so it will travel less distance in 1 second and hence the wavelength will always be shorter than that of vacuum, provided that the frequency always remains constant. Thank you so much professor.
@@ARNABBHOWMIK-y6n No worries about silly mistakes or questions you think are dumb. If I had a nickel for every dumb thought or question I had, I could buy a new house! I highly recommend asking any question regardless of how dumb you think they are. You may be missing something significant and big. One "dumb" question I had was what is the difference between D (electric flux density) and E (electric field intensity), as well as H and B. Those field quantities are talking about so commonly I thought it much be obvious so I never asked. When I finally figured it out, the answer was quite profound and gave me a whole new level of understanding of electromagnetics and optics. I hindsight, I don't think many EM instructors really know the difference so it is rarely taught. Keep at it and ask all questions!
It is a nice job you have done here, but you have to modify the orientation of H (180 degrees) in your last animation, because ExH is in the k direction (Right hand rule)
Thank you for pointing this out! Here I incorporated a phase shift, but too dramatic of one and it mostly looks 180 degrees away from where it should be. I noted this and will revise next time I edit this video.
Q) An unpolarized EM wave of 1 GHz frequency is incident at normal from air on to an unknown medium. If the standing wave ratio is 3, what is the impedance of medium 2? Assume that both mediums are lossless?
This is a standing wave problem. Below is the course website where you can see all of the videos and notes organized, as well as get links to many other learning resources. empossible.net/academics/emp3302/ Standing waves are covered in detail in Topic 7. There really is no such thing as an "unpolarized" electromagnetic wave. Since your wave is incident at normal incidence, polarization will not matter assuming the mediums are linear, homogeneous, and isotropic. Watch the videos up to standing waves and I think you will have all the information you need. This should be a relatively easy problem for you once you learn the information.
I wrote over 20 papers on metamaterials 18 years ago, and then switched my career to teaching maths and engineering to teenagers. I am still very interested in the research of metamaterials and after following your lectures in the past six years you have helped me make sense of the theoretical understanding of some crucial parameters. I wish I had those understanding 18 years ago when I had more time to consolidate the knowledge and practise it. Please continue to share your lessons or lectures, because it is making an impact for people like me who are still trying to understand metamaterials properties. Your delivery approach is very unique and accessible for beginner level into the subject, and not limited to MIT boffins.
Thank you! You have made my day!!! My metamaterials information is quite old now. I have learned more and better graphics skills. I need to redo and improve those materials! I am curious what you researched.
@@empossible1577 I researched on reduced sized unit cell elements. I thought by increasing capacitance and inductance of a single unit cell would reduce the resonance frequency or band gap frequency, so I applied Hilbert curves and convoluted elements while still keeping the vias. I then assisted in the practical development of wire medium.
@@sbu6thengineering At that scale, coupling short circuits the elements. I think that is why ideas like fractal antennas fall short of what we think should be possible. We are working on using the dielectric to effectively stretch space (think transformation optics) to reduce the mutual coupling in fractal-ish designs. So far, the idea has failed miserably. LOL
@@empossible1577 What frequency are you testing your ideas? While I love to endure THz and upwards as it seems is a trendy thing to do, I simply preferred 60GHz or lower to avoid plasmonic territories which is an area I don't have the capacity for. Also, imaging me going to my school headteacher asking for a funding for a 2nd hand THz VNA of USD 90000 for our 16 to 18 years old school projects, he must think I am having a laugh. As I don't have an anechoic chamber, much of my work now is mainly CST simulation and S11 measurement up to 6GHz. I get the teenage students to model antenna and unit cell on CST. They measure the bandgap frequency using two monopole antenna edge to edge of a 2D metasurface, I prefer the term high impedance surfaces back in Sievenpiper's days. I used to use FR4, now I get my students to 3D print the substrate using PLA filament of epsilon 2.2 to 2.9 depending the infill settings. I am having fun to try and develop metamaterials using standard classroom machines as I don't have hundreds of thousands of dollars funding, instead I get USD3000 school budget to spend on teaching consumables. I am working on developing a small size near field to far field computer controlled system using some left over stepping motors from an obsolete 3D printer. Do you have a working measurement setup to detect band gap of 2D or 3D metamaterial?
Brilliant. I have just had a penny-dropping monent watching this.
Thank you. What is a penny-dropping moment? I've never hear that expression.
@@empossible1577 If the penny drops, you suddenly understand something:
@@williamnelson4968 Thank you!
Fantastic stuff!
Thank you so much
Dear Professor, I think there is a slight mistake in the animation where the speed and wavelength change (around 9 minutes). Since the refractive index of medium 2 is higher than medium 2, the speed of the wave in medium 2 should be less, in that case the wavelength should increase instead of decreasing, since the frequency remains constant. Please correct me if I am wrong.
Best regards,
Arnab
The speed v, frequency f, and wavelength lam are related through
v = f * lam
Based on this, speed and wavelength will either both increase or both decrease. They will not do opposite things as frequency is changed.
I tend to think of the frequency as how fast the wave at a fixed point is moving up and down. If the wave is travelling slower, the wave does not travel as far before the wave cycles. This places the peaks and valleys at closer points (i.e. short wavelength). Give this some thought until it becomes intuitive.
Thank you for pointing out a potential mistake!
@@empossible1577 Dear professor. I understood my mistake that day itself but I forgot to delete my comment. It was a very silly mistake of understanding on my part, I am so sorry.
I think of it now in this way, the wave will travel the maximum distance (max wavelength) in a medium where the speed is the fastest, that is in vacuum (well, technically vacuum itself is not a medium), the wave travels 3*10^8 meters in 1 second. In any other medium, the wave will have less speed, so it will travel less distance in 1 second and hence the wavelength will always be shorter than that of vacuum, provided that the frequency always remains constant.
Thank you so much professor.
@@ARNABBHOWMIK-y6n No worries about silly mistakes or questions you think are dumb. If I had a nickel for every dumb thought or question I had, I could buy a new house!
I highly recommend asking any question regardless of how dumb you think they are. You may be missing something significant and big. One "dumb" question I had was what is the difference between D (electric flux density) and E (electric field intensity), as well as H and B. Those field quantities are talking about so commonly I thought it much be obvious so I never asked. When I finally figured it out, the answer was quite profound and gave me a whole new level of understanding of electromagnetics and optics. I hindsight, I don't think many EM instructors really know the difference so it is rarely taught.
Keep at it and ask all questions!
It is a nice job you have done here, but you have to modify the orientation of H (180 degrees) in your last animation, because ExH is in the k direction (Right hand rule)
Thank you for pointing this out! Here I incorporated a phase shift, but too dramatic of one and it mostly looks 180 degrees away from where it should be. I noted this and will revise next time I edit this video.
Q) An unpolarized EM wave of 1 GHz frequency is incident at normal from air on to an unknown medium. If the standing wave ratio is 3, what is the impedance of medium 2? Assume that both mediums are lossless?
This is a standing wave problem. Below is the course website where you can see all of the videos and notes organized, as well as get links to many other learning resources.
empossible.net/academics/emp3302/
Standing waves are covered in detail in Topic 7.
There really is no such thing as an "unpolarized" electromagnetic wave. Since your wave is incident at normal incidence, polarization will not matter assuming the mediums are linear, homogeneous, and isotropic.
Watch the videos up to standing waves and I think you will have all the information you need. This should be a relatively easy problem for you once you learn the information.
@@empossible1577 thank you so much