Hello! My expertise is Antenna Design with more than 40 years experience and more than 50 US Patents granted. I also give lectures on the subject; specifically on the Maxwell Equations and how they are used to design antennas. Keep up the good work!
Great video. As for the length, no need to apologize. I find the amount of information presented was great with the right amount that doesn't overwhelm us. Thanks and will be watching part 2.
8:20 No, an electric field can indeed exist without an magnetic field, and vice versa. The time term in Maxwells 3. and 4. equations just tells you than when one field is changed over time, the other is induced.
Yeah. I was shouting at the screen a few times during this vid, and this was one of those times. The other was during the clumsy attempt to explain how moving charges in an antenna create a propogating signal. GUYS. Moving charge creates a changing E field, which creates a changing B field, which creates a changing E field, etc. An experienced guitarist knows this better than these guys, just by knowing how pickups work. Yikes.
@@patrickmestabrookNo that is incorrect. Moving charges create a magnetic field. To be more precise a steady current creates a magnetic field. A changing current, charge being accelerated causes an EM/RF field, photon(s) which comprises a magnetic field component, an electric field component and propagating away from the wire at the speed of light. An electric field is created by the presence of charge. That charge can be stationary or moving.
as a physicist I was looking for this comment 👍 Edit: for those confused, a good example is a bar magnet. It has no electric field, but induces one of moved, so moved through a coil means you can measure an electric output from the coil
As a former Amateur Radio Operator (Technician II), I really enjoyed this. I’ve made all sorts of antennas, but I never really understood the math behind what I was doing.
One of my uncles was an Amateur Radio Operator. He introduced me into the world of electronics and antennas. May he rest in peace. Greetings from Panama 🇵🇦
@mikesmith1290 Cool, I'm a general class. I took a close pass at getting licensed when I was 11 or 12, but didn't quite get it done. I git my license (both tech + general) during the pandemic. Thinking about getting an extra class license in the next few years, also. I haven't done any DX yet, I'm working on getting that set up. If you have math questions I'll take a shot at them. I have a phd in engineering however this is not my area at all. I do optimization and estimation and machine learning and some statistics/ probability theory. I have other friends and connections though that are super solid at these topics though.
I hope you take this as a constructive comment because I think it's cool that you make these videos. Consider your audience when getting into technical stuff like Maxwell's equations. There are two kinds of viewers. Ones who are already familiar with the material and are protesting the inaccuracies like the claim that an electric field cannot exist without a magnetic field. The other is someone who hasn't learned (note i didn't write "studied") physics or electrical engineering. Do any of those viewers develop a better understanding of Maxwell's equations or electromagnetics by watching? They might be better served by an equation-free discussion of how moving charges create magnetic fields and how changing magnetic fields create electric fields. Discuss how when that induced electric field causes charges to move, that moving charge counters the magnetic field. People need to understand the fundamentals before you start throwing mathy looking stuff at them.
Few corrections on Maxwell's Equation - 1. 8:15 *Electric fields can exists without a Magnetic field.* There are actually two types of electric field - Electrostatic field and Induced Electric field. One is due to stationary charge distribution(Gauss law) and other one is due to a changing magnetic field(Faraday's laws). 2. 8:41 J is not displacement current. *J is the CURRENT density.* Displacement current is actually the other term in Ampere's Law which is ε(δE/δt).
~7:30 When speaking of the mathematics behind Maxwell's Equations: '∇' is the nabla symbol; however, when used in mathematics it is called the "del operator". When the ∇ is used on a scalar, e.g., ∆f, "del f", is called the "gradient of f." Used in a dot product on a vector, e.g., ∇ • B⃗ "Del dot B⃗ is called the "Divergence of B⃗". Used in a cross product it is called the Curl. "Del cross B⃗", ∇ x B⃗, is the Curl of B⃗. 73, W1JP
I thought the name del was commonly used to distinguish Nabla and the partial derivative symbol, so we would call the pd ‘del’ and the triangle ‘nabla’. After all, it’s just called grad without vector multiplication. Maybe I misunderstood or is different in physics
In three dimensions with Cartesian space, the operator can be interpreted as a shorthand for the column vector (d/dx, d/dy, d/dz). This gives you the three usages: gradient: compute partials (R^3 to R^3, elementwise), gives direction of steepest ascent and maximum rate of change for all directions at a point divergence: inner product (sum of partials, R^3 to scalar, or L1-norm of gradient), measures convexity of a scalar field at a point curl: outer product (R^3 to R^3), measures revolution of a vector field around a point, direction determines axis/direction of revolution (RHR) and magnitude determines total revolution
8:13 What can never understand is that the signal must propagate down the pipes of the antenna at the same speed its being received, instead of the arms sharpening the signal, would it not blur it? the build of antenna appears to assume that the signal is fed across the arms of the antenna instantly.
Thanks Derek for sharing. Antennas have always been captivating and fascinating. As hams, they are perhaps one of the best parts of the hobby to experiment and laarn from, and I encourage ALL to build their own when they can. 73
The discussion of the transition from separate E and M fields in the nearfield to an EM field in the farfield was a little muddled. The discussion in wiki is pretty good. One picture that is missing is the transition from either a high characteristic impedance at the antenna-free space interface from a dipole, or the low characteristic impedance from a loop antenna to 120 x pi (377 Ohm) free space impedance. This is shown in Henry Ott's book on EMI...
What I don't get is that the rf transmitter and reliever devices that we get online like NRF24l01 this are only able to transmit the signal up to 1km max. How does the mobile phone is able to transmit the signal to the cell tower which in some cases 10 km away from it
Hello, Thank you for your video. One question I have regarding maxwells equation 1 and 2. You used the sink and source analogy to equation two ( electric displacement) but I had learned in the past that for magnets being monopole (equation 1), this was a reminder that magnet are not monopoles and hence no source and sink. So, just wondering if I had it wrong or this was a typo on your side? Thank you!
I qualified in both Electrical & Mechanical Engineering at the National University of Ireland back in the early 1960ies !!! That means I’m eighty now !!!! I assume that your intention is to get youngsters interested in the field of radio frequency transmission & reception. A very noble enterprise indeed. Might I suggest that to begin with you omit all the Maxwell, Faraday etc stuff & just focus on a composite wave which can be transmitted & received over a range of frequencies depending primarily on the aerial. Then explain in simple, preferably non technical terms how this works . Once you’ve achieved this you can step slowly into the simple equations which in turn give a more comprehensive understanding of what’s going on. Only a suggestion. !!!
Thank you for this video. Please correct the very prevalent error also seen in so many otherwise fine textbooks and other illustrations of wave phenomenon. The zero crossing points of the electric and magnetic fields do not occur at the same time or place in space but are offset by 90 degrees. You too show propagating waves with E and B fields arriving at the zero point at the same time and place.
I've always wondered. How, with all the RF energy signals whatever that pervade our modern environment, how do you separate the thousands of signals that make up the soup of signals how is ONE particular signal able to be seperated.
Always found this topic fascinating. Often times I wonder how is an antenna capable of picking up and interpreting electric and magnetic fields impinging upon it and turning it into intelligence?
You graphical display of the electric and magnetic fields are incorrect.... The one is a derivative of the other, which is equivalent to a 90degree phase shift. Think of the two components E, B being kinetic and potential energy, and exchange from one to the other resulting in the two fields, and thus 90 degree phase shift (as per Hilbert transform)
I would like to ask you for help on measuring rf field strength. Is there an accurate way to measure the rf field where the location is inside of one wavelength? I would like to measure frequencies that are in the hf amateur radio bands starting at 1.7 mHz and going up to 30 mHz. Do I want to measure the e-field or the h-field? I think that the e-field would be easier to measure. The equipment I have is a Siglent spectrum analyzer which I believe to be accurate and I have an older field strength meter, EFS-1, which works but I am not sure about the calibration. I read a paper from Keysight Technologies which describes how to use a spectrum analyzer to measure the e-field. (859xE: How Do You Measure Electric Field Strength with an Antenna and Spectrum Analyzer?) I'm not sure about what they call the antenna factor which gives volts/meter in terms of dB's. I checked into buying an accurate rf field strength meter that can measure lower hf frequencies. I found them to be very expensive. What is driving this project, is the FCC requirement to measure rf exposure around the amateur radio station. The ARRL has an online rf exposure calculator. I have several unknown factors at my station and I would like to be more accurate. I also want to learn more about rf fields. Thank you.
At about 11 min, the physics that you are looking for is simply that accelerating charged particles emit photons… except bound electrons. It is described by the classical Larmor relationship.
I always viewed transmitters as giant lamps and the RF is the light and as long as a radio can see the light it can pick up the station. I know it’s not super accurate to see it that way and much more complicated than that but it simplified it for me so it kinda helped
There are so many types of antennas. Folded dipoles are the simplest. But vertical, Yagi, and Quads. The real question is who is still on 80, 40, 15 and 10 meters? When hams have moved to 2 m and 6 m. And just how good are tiny built in antennas on newer compact SW radios. K6AGE.
Photons are just the dualistic particle equivalent of an electromagnetic wave. So every physics in the vid is all about photons - just in the wave state.
@@SRJDPO that doesn’t really make sense. Photons are discrete unidirectional quanta. This video talks about omnidirectional propagating EM waves. I don’t see how the two can be drop in equivalents, which is why I’m asking the question. I want to understand what the relationship is and when you would use photon math instead of EM math.
Photons are quantum mechanical constructs. Maxwell's Equations are classical (not quantum mechanical) constructs. One does not require using the concept of a photon to perform antenna design and analysis nor describe electromagnetic wave propagation. The concept of photons was developed to explain observed phenomenon that Maxwell's Equations could not solve, i.e. the photoelectric effect.
@@garymiller6151 thanks. I get that it’s not needed for the common application. I’ve seen my question asked in quite a few places and “QED is not needed” is always the handwavey response, which is very unsatisfying. QED is supposed to be a more accurate replacement for classical models. So in theory, although it’s not necessary, it should be entirely possible to describe antenna physics using QED, and therefore answer the question of how photons fit in and how discretised unidirectional quanta get created and absorbed.
I have watched all of Andrew McNeil wifi videos and build a bunch. The biquad with parabolic reflector is my most powerful build. I have some documentation and videos if your interested. It was a dual element 5.8ghz biquad with parabola.
Haven't heard of any such phenomenon. The antenna's performance depends on whether there is an obstacle in between the transmit and receive antennas as it attenuates the EM wave and on the radiation pattern of the antenna. Some antenna radiate more EM waves in one direction, for example the dish antenna which connects to your TV and communicates with the satellite. In my opinion, a magnet placed very close to an antenna will disrupt the EM wave and you will get an even weaker signal from the antenna on your receiving device. But, that's just what I think would happen. I don't have any proof for it.
@AmRad Podcast There is also an error in the equation 8:28 - there should be no factor 1/c^2. This factor, or epsilon0*mu0, is to be found in the wave equations derived from Maxwell's equations: (1) Nabla^2*E-epsilon0*mu0*(de^2_E/de_t^2)=0 for electric field and (2) Nabla^2*H-epsilon0*mu0*(de^2_H/de_t^2)=0 for magnetic field. Because there is formula epsilon0*mu0=1/c^2 for the speed of light in vacuum we can also write Nabla^2*E-(1/c^2)*(de^2_E/de_t^2)=0 and Nabla^2*H-(1/c^2)*(de^2_H/de_t^2)=0. Greetings from Poland!
@@JensenPlaysMC Oh yes, you're right, excuse me. But I know different form of the equation (that is in a Polish book for students of electronics) which I mixed up with that of 8:28. The version is: Nabla x H = J + de D / de t where there are different vectors: H which is B / mu or B / mu0 in vacuum and D which is epsilon * E or epsilon0 * E in vacuum. This form is more clear in my view and it corresponds well with the previous Maxwell's equation: Nabla x E = - de B / de t . I also found a form: Nabla x B = mu * (J + epsilon * (de E / de t)). If we factorize this we achieve mu * epsilon or mu0 * epsilon0 which is mu0 * J and (1 / c^2) * (de E / de t) as in 8:28 because mu0 * epsilon0 = 1 / c^2.
The simple reason why antennae produce rf is that the driving signal is accelerating electrons in the aerial conducting material. accelerating electrons radiate electromagnetic radiation.
Minute 03:03: “Assumes your earth is spherical in nature”: is that a reference to flat-earthers? That thought came to my mind immediately and then I couldn’t stoop laughing 😂
@@slayerdrum wait an a second.. but waves can bounce the same way between earth atmosphere even if the earth is flat sooooo.. You just lighted up the flat earthers ideas 😂
@@albyboy4278 You‘re absolutely right. My comment really only was about that one sentence. In particular, the „assume your earth is spherical…“. That just made me laugh because…well… I think we can treat that as a fact by now :D
If some smarter than myself knows the answer to this: Those perpendicular magnetic and electric fields are always represented with waves that have the same phase. My understanding is that antenna though generate them with quarter-phase phase difference? Have I understood this correctly, and if so is there some natural instance where the have the same phase? I would like some certainty on this as this has lived rent free on my head for few decades.
i just learned this today, light and radio waves reflect the same, it seems obvious now, but if you put a reflective material on a rf reflecting dish you can make a light focusing fire hazard.
I like the speaker/antenna analogy. The math is over my head, so the analogy helps. I think more of the energy being moved around. For a speaker, some energy is used to move air molecules while other energy creates heat at the voice coil. For antennas some energy is radiated away from the antenna while other energy is bounced back to the transmitter.
I wish you guys were around 55 years ago when I was trying to absorb the concept of divergence and curl after failing differential and integral several times 😢. (Not that I do now.)
@@LeoFreemanAUST I think, in that case, we have a sink or source of an electric field like an electron. However the electron has also a magnetic moment with an angular spin (i.e. also changing magnetic field) - however just guessing (I may be wrong)....
At 9:25 Derek asks for an explanation for antenna radiation and Sterling gives him Maxwell's equations instead of an explanation. Welcome to Science. Consider this: There is a massless medium of the galaxy that moves at c, and is made of matter and energy, but not normal baryonic matter. Any transmitting antenna that is correctly tuned for its environment (the medium's environment) acts (inducts) like a transformer as it matches the wave speed of the signal to the wave speed of the medium.
Simply while talking pressure waves move in free space , similarly the spinning electrons create magnetic field and moving electrons creates electric field when there is positive voltage a.c wave these are applied on the rod and in a fraction of a second they are again taken out which are electrons taken out from the system making the magnetic field field converse because magnetic field is a closed loop every time, so with magnetic field is perpendicular to electric field in propagation they form em wave this is what closed loops and the way they propagation is done is by pushing one wave like the constant water when stone is thrown one wave pushes other in front they push each other "waves push each othere and electrons push each other" this is fundamental how they push is Maxwell law😊
That depends on whether or not you believe he invented radio truly. There were others, such as Tesla, Popov, Nathan B. Stubblefield, and Reginald Fessenden all laid groundwork. I could even argue that Heinrich Hertz discovered radio. Marconi made it well-known...and profitable. Don't forget the decades of legal litigation on this matter.
@@W8RIT1 That is always the way wit new developments and major projects, a lot of people have inputs but sometimes only one or two have the vision, motivation and financial support to make it work. The inventors often don't have the commercial knowledge or charisma to sell the idea to others.
9:30 Think the simple explanation you're looking for there is that the quantum field is already there it's already wobbling about a near zero state, you're giving it a jiggle 👍 so the field being present to be jiggled is what allows it to propagate..... Or that is how I picture it, like ""empty"" space is full of jelly.
Hi sir good day to you where ever you are i just want to ask a question about my ssb 710 icom why does the power supply flactuate whenever it transmit? Even other devices turn off suddenly whenever i talk.
![Lp. Сердце Вселенной #60 РОЖДЕНИЕ ЛОЛОЛОШКИ [Финал] • Майнкрафт](http://i.ytimg.com/vi/YoR0pAV9FVQ/mqdefault.jpg)
Watch the full interview with Sterling Mann and ask Derek questions on the element14 Community! bit.ly/3IIVEKl
So much to learn here. Looking forward to part 2!
Hello! My expertise is Antenna Design with more than 40 years experience and more than 50 US Patents granted. I also give lectures on the subject; specifically on the Maxwell Equations and how they are used to design antennas. Keep up the good work!
You need your own channel!
I'd be very interested to watch videos you could put out just discussing any aspect of antennas from your perspective.
@@robhill5732 planning on doing some videos? I'll be thrilled to hear you
dayum
Hello sir, is there a way to contact you? I am starting my research journey...
Great video. As for the length, no need to apologize. I find the amount of information presented was great with the right amount that doesn't overwhelm us. Thanks and will be watching part 2.
8:20 No, an electric field can indeed exist without an magnetic field, and vice versa. The time term in Maxwells 3. and 4. equations just tells you than when one field is changed over time, the other is induced.
Yeah. I was shouting at the screen a few times during this vid, and this was one of those times.
The other was during the clumsy attempt to explain how moving charges in an antenna create a propogating signal. GUYS. Moving charge creates a changing E field, which creates a changing B field, which creates a changing E field, etc. An experienced guitarist knows this better than these guys, just by knowing how pickups work. Yikes.
@@patrickmestabrookNo that is incorrect.
Moving charges create a magnetic field. To be more precise a steady current creates a magnetic field.
A changing current, charge being accelerated causes an EM/RF field, photon(s) which comprises a magnetic field component, an electric field component and propagating away from the wire at the speed of light.
An electric field is created by the presence of charge. That charge can be stationary or moving.
But can you say that a static elektric field is existing... not much of an existence if it couldnt even create itself in time.
as a physicist I was looking for this comment 👍
Edit: for those confused, a good example is a bar magnet. It has no electric field, but induces one of moved, so moved through a coil means you can measure an electric output from the coil
This should be the top comment.
As a former Amateur Radio Operator (Technician II), I really enjoyed this. I’ve made all sorts of antennas, but I never really understood the math behind what I was doing.
One of my uncles was an Amateur Radio Operator. He introduced me into the world of electronics and antennas. May he rest in peace. Greetings from Panama 🇵🇦
@mikesmith1290 Cool, I'm a general class. I took a close pass at getting licensed when I was 11 or 12, but didn't quite get it done. I git my license (both tech + general) during the pandemic. Thinking about getting an extra class license in the next few years, also. I haven't done any DX yet, I'm working on getting that set up. If you have math questions I'll take a shot at them. I have a phd in engineering however this is not my area at all. I do optimization and estimation and machine learning and some statistics/ probability theory. I have other friends and connections though that are super solid at these topics though.
Former ? Bro get back in the game its as alive as it was a long time ago
We really appreciate you, future Derek
I hope you take this as a constructive comment because I think it's cool that you make these videos. Consider your audience when getting into technical stuff like Maxwell's equations. There are two kinds of viewers. Ones who are already familiar with the material and are protesting the inaccuracies like the claim that an electric field cannot exist without a magnetic field. The other is someone who hasn't learned (note i didn't write "studied") physics or electrical engineering. Do any of those viewers develop a better understanding of Maxwell's equations or electromagnetics by watching? They might be better served by an equation-free discussion of how moving charges create magnetic fields and how changing magnetic fields create electric fields. Discuss how when that induced electric field causes charges to move, that moving charge counters the magnetic field. People need to understand the fundamentals before you start throwing mathy looking stuff at them.
💯
Yeah, antennas have always been "black magic" to me, now they are "magic". Looking forward to part 2. I am learning a lot from your channel - thanks!
Few corrections on Maxwell's Equation -
1. 8:15 *Electric fields can exists without a Magnetic field.* There are actually two types of electric field - Electrostatic field and Induced Electric field. One is due to stationary charge distribution(Gauss law) and other one is due to a changing magnetic field(Faraday's laws).
2. 8:41 J is not displacement current. *J is the CURRENT density.* Displacement current is actually the other term in Ampere's Law which is ε(δE/δt).
@@jitulhussain7902 I came here to make the same comment.
~7:30 When speaking of the mathematics behind Maxwell's Equations: '∇' is the nabla symbol; however, when used in mathematics it is called the "del operator". When the ∇ is used on a scalar, e.g., ∆f, "del f", is called the "gradient of f." Used in a dot product on a vector, e.g., ∇ • B⃗ "Del dot B⃗ is called the "Divergence of B⃗". Used in a cross product it is called the Curl. "Del cross B⃗", ∇ x B⃗, is the Curl of B⃗.
73,
W1JP
There we go..This person knows what he/she is talking about
I thought the name del was commonly used to distinguish Nabla and the partial derivative symbol, so we would call the pd ‘del’ and the triangle ‘nabla’. After all, it’s just called grad without vector multiplication. Maybe I misunderstood or is different in physics
It's really good to see the way the terminology and its behavior change.
In three dimensions with Cartesian space, the operator can be interpreted as a shorthand for the column vector (d/dx, d/dy, d/dz). This gives you the three usages:
gradient: compute partials (R^3 to R^3, elementwise), gives direction of steepest ascent and maximum rate of change for all directions at a point
divergence: inner product (sum of partials, R^3 to scalar, or L1-norm of gradient), measures convexity of a scalar field at a point
curl: outer product (R^3 to R^3), measures revolution of a vector field around a point, direction determines axis/direction of revolution (RHR) and magnitude determines total revolution
Thank you for this video. I did have trouble in understanding the section on Maxwell's equations. I will have to spend some time on that.
Absolutely amazing video. I never understood this before. Antenna designers said it was ultimately "magic" that made them work. Thank you!
*THANKS A LOT*
Congrats on the channel
What if we use copper beside aluminum?
Glad to have found your channel.
I appreciate information and science rich videos.
You are helping the world become scientifically literate.
what design principles changed to allow us to take advantage of short wave frequencies better?
at 8:49 isnt J actually the conduction current density while the other half of the equation (on the same side) is the displacement current.
8:13 What can never understand is that the signal must propagate down the pipes of the antenna at the same speed its being received, instead of the arms sharpening the signal, would it not blur it? the build of antenna appears to assume that the signal is fed across the arms of the antenna instantly.
Hi great video - I'm interested in the electromagnetic wave itself, in that i guess the wave (itself) is composed of photons?
Really appreciate your efforts. Keep it up and waiting for Part-2 🤟
Great work guys. I am hugely impressed by these videos, little courses, and your presentations. Much appreciated. Sub.
Thanks Derek for sharing. Antennas have always been captivating and fascinating. As hams, they are perhaps one of the best parts of the hobby to experiment and laarn from, and I encourage ALL to build their own when they can. 73
Antenna connection at 6:00 is missing a balun.
The discussion of the transition from separate E and M fields in the nearfield to an EM field in the farfield was a little muddled. The discussion in wiki is pretty good. One picture that is missing is the transition from either a high characteristic impedance at the antenna-free space interface from a dipole, or the low characteristic impedance from a loop antenna to 120 x pi (377 Ohm) free space impedance. This is shown in Henry Ott's book on EMI...
Any mention of dipole ?
Our church where granted a LPFM permit by the FCC we need some advice about what will be the best antenna for our church station
What I don't get is that the rf transmitter and reliever devices that we get online like NRF24l01 this are only able to transmit the signal up to 1km max. How does the mobile phone is able to transmit the signal to the cell tower which in some cases 10 km away from it
Great job Derek 👍
Hello,
Thank you for your video. One question I have regarding maxwells equation 1 and 2. You used the sink and source analogy to equation two ( electric displacement) but I had learned in the past that for magnets being monopole (equation 1), this was a reminder that magnet are not monopoles and hence no source and sink.
So, just wondering if I had it wrong or this was a typo on your side? Thank you!
Thank you for the informative presentation.
Derek is sporting a sweet looking hat. 🤘
How do you power the antenna? How do you recieve the power in the receiver?
Great info mate. It answered a question that I could not find an answer for. Thank you!
Which software are you using for the simulations?
Glad to see your channel and the information is very use full.
The questions you asked your guest were Feynman level. How does the magic happen? :)
I had a hunch about this information but now it's all so crystal clear.
WHERE IS PART 2!? Not out yet? Nooooo, can't wait!
Thank you, my favourite part was at 11:00.
I qualified in both Electrical & Mechanical Engineering at the National University of Ireland back in the early 1960ies !!! That means I’m eighty now !!!! I assume that your intention is to get youngsters interested in the field of radio frequency transmission & reception. A very noble enterprise indeed.
Might I suggest that to begin with you omit all the Maxwell, Faraday etc stuff & just focus on a composite wave which can be transmitted & received over a range of frequencies depending primarily on the aerial.
Then explain in simple, preferably non technical terms how this works .
Once you’ve achieved this you can step slowly into the simple equations which in turn give a more comprehensive understanding of what’s going on.
Only a suggestion. !!!
Thank you for this video. Please correct the very prevalent error also seen in so many otherwise fine textbooks and other illustrations of wave phenomenon. The zero crossing points of the electric and magnetic fields do not occur at the same time or place in space but are offset by 90 degrees.
You too show propagating waves with E and B fields arriving at the zero point at the same time and place.
Hi, please post a video on PCB design courses in details
Any possibility to explain its mathematical derivations
Great tutorial 👌
I've always wondered. How, with all the RF energy signals whatever that pervade our modern environment, how do you separate the thousands of signals that make up the soup of signals how is ONE particular signal able to be seperated.
Always found this topic fascinating. Often times I wonder how is an antenna capable of picking up and interpreting electric and magnetic fields impinging upon it and turning it into intelligence?
It's not quite clear to me how the 90 degree out-of-phase E and B fields in an antenna become in-phase when an electromagnetic wave propagates?
Where is the link to part 2? :/
You graphical display of the electric and magnetic fields are incorrect....
The one is a derivative of the other, which is equivalent to a 90degree phase shift.
Think of the two components E, B being kinetic and potential energy, and exchange from one to the other resulting in the two fields, and thus 90 degree phase shift (as per Hilbert transform)
Holy mackerel, I don't know math. I want that Black Sabbs shirt, though!
What, no comment about Dr. Brown's yellow Case?
In short, an antenna is an impedance match between your feedline's impedance, and the 377Ω impedance of free space.
What intrigues me is how do electric field flows in an open circuit. It shoudn't a close circuit to electric field to flow?
I would like to ask you for help on measuring rf field strength. Is there an accurate way to measure the rf field where the location is inside of one wavelength? I would like to measure frequencies that are in the hf amateur radio bands starting at 1.7 mHz and going up to 30 mHz. Do I want to measure the e-field or the h-field? I think that the e-field would be easier to measure. The equipment I have is a Siglent spectrum analyzer which I believe to be accurate and I have an older field strength meter, EFS-1, which works but I am not sure about the calibration. I read a paper from Keysight Technologies which describes how to use a spectrum analyzer to measure the e-field. (859xE: How Do You Measure
Electric Field Strength with an
Antenna and Spectrum
Analyzer?) I'm not sure about what they call the antenna factor which gives volts/meter in terms of dB's. I checked into buying an accurate rf field strength meter that can measure lower hf frequencies. I found them to be very expensive. What is driving this project, is the FCC requirement to measure rf exposure around the amateur radio station. The ARRL has an online rf exposure calculator. I have several unknown factors at my station and I would like to be more accurate. I also want to learn more about rf fields. Thank you.
At about 11 min, the physics that you are looking for is simply that accelerating charged particles emit photons… except bound electrons. It is described by the classical Larmor relationship.
I always viewed transmitters as giant lamps and the RF is the light and as long as a radio can see the light it can pick up the station. I know it’s not super accurate to see it that way and much more complicated than that but it simplified it for me so it kinda helped
is there Elektric fields without magnetic fields?
That was great... much more of that please! :)
Nicely done
Is that a Flux Capacitor behind your left shoulder ?
All capacitors are flux capacitors.
Right next to the box of Plutonium.
Thanks for sharing, I still don't get it though. I'm not very educated in this area, but very curious.
moving charge creates a magnetic field, changing magnetic fields generate voltage, changing electric field create magnetic fields -- maxwell's laws
Yay! Calculus and linear algebra!
There are so many types of antennas. Folded dipoles are the simplest. But vertical, Yagi, and Quads. The real question is who is still on 80, 40, 15 and 10 meters? When hams have moved to 2 m and 6 m. And just how good are tiny built in antennas on newer compact SW radios. K6AGE.
Very nice presentation
Is it possible to be electrocuted from an aerial if not, how come ?
Wow so well explained 👏
Thank you!
I'm curious. In 2024, why compare G2Core to 8-bit grbl instead of 32-bit grblHAL?
Where do photons fit into all of this? Does photon maths/physics ever need to be considered?
Photons are just the dualistic particle equivalent of an electromagnetic wave. So every physics in the vid is all about photons - just in the wave state.
@@SRJDPO that doesn’t really make sense. Photons are discrete unidirectional quanta. This video talks about omnidirectional propagating EM waves. I don’t see how the two can be drop in equivalents, which is why I’m asking the question. I want to understand what the relationship is and when you would use photon math instead of EM math.
@@br3nto lemme know what you find/ where you find those kind of details. curious
Photons are quantum mechanical constructs. Maxwell's Equations are classical (not quantum mechanical) constructs. One does not require using the concept of a photon to perform antenna design and analysis nor describe electromagnetic wave propagation. The concept of photons was developed to explain observed phenomenon that Maxwell's Equations could not solve, i.e. the photoelectric effect.
@@garymiller6151 thanks. I get that it’s not needed for the common application. I’ve seen my question asked in quite a few places and “QED is not needed” is always the handwavey response, which is very unsatisfying. QED is supposed to be a more accurate replacement for classical models. So in theory, although it’s not necessary, it should be entirely possible to describe antenna physics using QED, and therefore answer the question of how photons fit in and how discretised unidirectional quanta get created and absorbed.
I'm a retired teacher, but occasionally I teach telecom. Can I use your material, as long as it obviously cites its authorship?

I have watched all of Andrew McNeil wifi videos and build a bunch. The biquad with parabolic reflector is my most powerful build. I have some documentation and videos if your interested. It was a dual element 5.8ghz biquad with parabola.
Very interesting! Thanks.
great explanation ! ♥️🇲🇦
Thank you Derek! You are doing good job!
Can magnets increase performance of antenna ?
Haven't heard of any such phenomenon. The antenna's performance depends on whether there is an obstacle in between the transmit and receive antennas as it attenuates the EM wave and on the radiation pattern of the antenna. Some antenna radiate more EM waves in one direction, for example the dish antenna which connects to your TV and communicates with the satellite.
In my opinion, a magnet placed very close to an antenna will disrupt the EM wave and you will get an even weaker signal from the antenna on your receiving device. But, that's just what I think would happen. I don't have any proof for it.
J is not displacement current, mu0 de/dt is. Also an E field can exist without a B field, just not a solenoidal one.
@AmRad Podcast There is also an error in the equation 8:28 - there should be no factor 1/c^2. This factor, or epsilon0*mu0, is to be found in the wave equations derived from Maxwell's equations: (1) Nabla^2*E-epsilon0*mu0*(de^2_E/de_t^2)=0 for electric field and (2) Nabla^2*H-epsilon0*mu0*(de^2_H/de_t^2)=0 for magnetic field. Because there is formula epsilon0*mu0=1/c^2 for the speed of light in vacuum we can also write Nabla^2*E-(1/c^2)*(de^2_E/de_t^2)=0 and Nabla^2*H-(1/c^2)*(de^2_H/de_t^2)=0.
Greetings from Poland!
@@erykbaradziej3639 This is wrong, The video is using SI units, The factor is correct.
@@JensenPlaysMC Oh yes, you're right, excuse me. But I know different form of the equation (that is in a Polish book for students of electronics) which I mixed up with that of 8:28. The version is: Nabla x H = J + de D / de t where there are different vectors: H which is B / mu or B / mu0 in vacuum and D which is epsilon * E or epsilon0 * E in vacuum. This form is more clear in my view and it corresponds well with the previous Maxwell's equation: Nabla x E = - de B / de t . I also found a form: Nabla x B = mu * (J + epsilon * (de E / de t)). If we factorize this we achieve mu * epsilon or mu0 * epsilon0 which is mu0 * J and (1 / c^2) * (de E / de t) as in 8:28 because mu0 * epsilon0 = 1 / c^2.
The simple reason why antennae produce rf is that the driving signal is accelerating electrons in the aerial conducting material. accelerating electrons radiate electromagnetic radiation.
Minute 03:03: “Assumes your earth is spherical in nature”: is that a reference to flat-earthers? That thought came to my mind immediately and then I couldn’t stoop laughing 😂
@@slayerdrum wait an a second.. but waves can bounce the same way between earth atmosphere even if the earth is flat sooooo..
You just lighted up the flat earthers ideas 😂
@@albyboy4278 You‘re absolutely right. My comment really only was about that one sentence. In particular, the „assume your earth is spherical…“. That just made me laugh because…well… I think we can treat that as a fact by now :D
If some smarter than myself knows the answer to this:
Those perpendicular magnetic and electric fields are always represented with waves that have the same phase. My understanding is that antenna though generate them with quarter-phase phase difference? Have I understood this correctly, and if so is there some natural instance where the have the same phase?
I would like some certainty on this as this has lived rent free on my head for few decades.
Many thanks ❤
I'm an Engineer myself and I honestly can say: content like this makes universities kinda redundant...
People like me watch these contents as review😅
multiple errors. may be you should do some revision.
i just learned this today, light and radio waves reflect the same, it seems obvious now, but if you put a reflective material on a rf reflecting dish you can make a light focusing fire hazard.
I like the speaker/antenna analogy. The math is over my head, so the analogy helps. I think more of the energy being moved around. For a speaker, some energy is used to move air molecules while other energy creates heat at the voice coil. For antennas some energy is radiated away from the antenna while other energy is bounced back to the transmitter.
Blast from the past, in the early 2000s i worked for Radiosoft writing software to do interference studies for the FCC. Memories.
I wish you guys were around 55 years ago when I was trying to absorb the concept of divergence and curl after failing differential and integral several times 😢. (Not that I do now.)
8:13 small correction: an electric field can't exist without a _change_ in the magnetic field
Just wondering, though; about the case of a static electric charge?
@@LeoFreemanAUST I think, in that case, we have a sink or source of an electric field like an electron. However the electron has also a magnetic moment with an angular spin (i.e. also changing magnetic field) - however just guessing (I may be wrong)....
@@LeoFreemanAUST The original definition of electric was "like amber".
All that beautiful TMDE I used to work on!
At 9:25 Derek asks for an explanation for antenna radiation and Sterling gives him Maxwell's equations instead of an explanation. Welcome to Science.
Consider this: There is a massless medium of the galaxy that moves at c, and is made of matter and energy, but not normal baryonic matter. Any transmitting antenna that is correctly tuned for its environment (the medium's environment) acts (inducts) like a transformer as it matches the wave speed of the signal to the wave speed of the medium.
Simply while talking pressure waves move in free space , similarly the spinning electrons create magnetic field and moving electrons creates electric field when there is positive voltage a.c wave these are applied on the rod and in a fraction of a second they are again taken out which are electrons taken out from the system making the magnetic field field converse because magnetic field is a closed loop every time, so with magnetic field is perpendicular to electric field in propagation they form em wave this is what closed loops and the way they propagation is done is by pushing one wave like the constant water when stone is thrown one wave pushes other in front they push each other "waves push each othere and electrons push each other" this is fundamental how they push is Maxwell law😊
Very good vid 😊
Thank you ✊
how far does a beam of light travel in a nano second?
Just shows how much of a Genius Marconi was.
That depends on whether or not you believe he invented radio truly. There were others, such as Tesla, Popov, Nathan B. Stubblefield, and Reginald Fessenden all laid groundwork. I could even argue that Heinrich Hertz discovered radio. Marconi made it well-known...and profitable. Don't forget the decades of legal litigation on this matter.
@@W8RIT1 That is always the way wit new developments and major projects, a lot of people have inputs but sometimes only one or two have the vision, motivation and financial support to make it work. The inventors often don't have the commercial knowledge or charisma to sell the idea to others.
very kewl :) like such topics
9:30 Think the simple explanation you're looking for there is that the quantum field is already there it's already wobbling about a near zero state, you're giving it a jiggle 👍 so the field being present to be jiggled is what allows it to propagate..... Or that is how I picture it, like ""empty"" space is full of jelly.
Bro… I’m a mechatronics technician but this is next level 😳 radio frequencies are cool!
Please add FSPL to your loss contributors as the most important one.
Second part pls
“Assuming *your* earth is spherical”
Hahahaha! Nice burn.
? So why do cell companies have really bad service. Tower 1/4 mile away yet mostly no service.
Awesome.
Hi sir good day to you where ever you are i just want to ask a question about my ssb 710 icom why does the power supply flactuate whenever it transmit? Even other devices turn off suddenly whenever i talk.