Antennas Part I: Exploring the Fundamentals of Antennas - DC To Daylight
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- Опубликовано: 22 май 2024
- Derek has always been interested in antennas and radio wave propagation; however, he's never spent the time to understand how the wiggling of electrons in a wire can actually produce RF radiation.
So, in this theory-based episode of DC to Daylight, Derek discusses antenna physics, shows how a dipole antenna radiates RF, and demonstrates how that RF behaves with a receiver antenna. And, where Derek needs some help with the details, he calls in an expert, Sterling Mann, who works in the field of RF. In the next application-based episode, we'll build our own antenna and use it to communicate around the globe!
Watch the full interview with Sterling Mann and ask Derek questions on the element14 Community! bit.ly/3IIVEKl
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#0:00 Welcome to DC To Daylight
#1:20 Antennas
#3:05 Sterling Mann
#4:05 What Is an Antenna?
#6:18 Maxwell's Equations
#9:25 Sterling Explains
#12:55 Give Your Feedback
#antenna #antennas #radiofrequency #maxwellequations #dipole 
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Watch the full interview with Sterling Mann and ask Derek questions on the element14 Community! bit.ly/3IIVEKl
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.
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.
~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
So much to learn here. Looking forward to part 2!
Thanks! It's quite a lot of information to cram into one video, so we needed to split it up. Yes, part 2 is coming soon - and as usual, there will be an application video to follow. Happy to have you! -Derek
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.
Thank you Derek! You are doing good job!
Glad to have found your channel.
I appreciate information and science rich videos.
You are helping the world become scientifically literate.
Really appreciate your efforts. Keep it up and waiting for Part-2 🤟
We really appreciate you, future Derek
Thanks 7Alfa - I always appreciate your supportive comments.
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
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.
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.
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!
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!
That's awesome to hear that it's more understandable now - so glad you are here. Believe me, this is one of those topics that I still have difficulty wrapping my head around, because I can't see the thing! More cool stuff in the pipeline so make sure to come back. -Derek
Very nice presentation
Thank you for the informative presentation.
Derek is sporting a sweet looking hat. 🤘
Hook 'em! -Derek
Very good vid 😊
Thank you ✊
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!
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.
what design principles changed to allow us to take advantage of short wave frequencies better?
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...
Ott's book is a fantastic read. Highly recommend to all interested in EMI or radiated/conducted emissions and good info on layer stackup. Yes what you mentioned is missing. However, it's always difficult to determine how deep to go on a subject. Maybe in the future we can dig even deeper. -Derek
WHERE IS PART 2!? Not out yet? Nooooo, can't wait!
Thank you, my favourite part was at 11:00.
It's in the pipeline.. The animation *is* mesmerizing. Thanks for the feedback. -Derek
Which software are you using for the simulations?
Great tutorial 👌
Thanks Hagop. It was fun.. Keep coming back, because we're going to talk more about antenna engineering and after part II there'll be the application video which is going to be a blast. -Derek
Wow so well explained 👏
Thank you! -Derek
Yay! Calculus and linear algebra!
Not tooooo much though. -Derek
Great job Derek 👍
Thanks for checking in!
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.
That was great... much more of that please! :)
Excellent... You got it! -Derek
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.)
great explanation ! ♥️🇲🇦
Thank you! -Derek
Where is the link to part 2? :/
I had a hunch about this information but now it's all so crystal clear.
Thanks. I hope it was helpful. More practical antenna content is coming in part II. -Derek
How do you power the antenna? How do you recieve the power in the receiver?
Finally! Marvell, and propogagation to infinity
"Assumes your Earth is spherical in nature."
Oh.
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.
Hi Andy. Thanks for your comment. Unfortunately, I have trouble with simple reasons! 🙃
True, accelerating charged particles radiate RF, (intended and un-intended radiators) but I thought it would be fun to look under the hood of Maxwell (or maybe it was just an excuse to talk to Sterling). 😀 -Derek
I like how there's a random "how to cook everything" book just sitting there
Any possibility to explain its mathematical derivations
very kewl :) like such topics
Thanks! -Derek
Ha love the disclaimer about your earth being spherical
“Assuming *your* earth is spherical”
Hahahaha! Nice burn.
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.
Thanks for sharing, I still don't get it though. I'm not very educated in this area, but very curious.
Second part pls
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.
I'm curious. In 2024, why compare G2Core to 8-bit grbl instead of 32-bit grblHAL?
I'm a retired teacher, but occasionally I teach telecom. Can I use your material, as long as it obviously cites its authorship?

What intrigues me is how do electric field flows in an open circuit. It shoudn't a close circuit to electric field to flow?
At about 02:02 in this video:
*_"Ah, nuts...."_*
🤭🤭🤭
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.
Outstanding info. When future Derek had the Sabbath shirt on, he was awesome! Just sayin...
Thanks Jim! That future guy is a troublemaker. (And we only talk about future Derek in future tense) 😁
at 8 min it almost started then back to chatting with friend about arithmetic and a bit of math
Why not just explain what physical characteristics μ and ε are meant to account for: the stiffness and elasticity of the stuff em waves propagate through?
9:25 "Sterling Explains". Hahahaha. yeah. Sterling doesn't know, but it took him a long time to fail to say it.
Is that a Flux Capacitor behind your left shoulder ?
All capacitors are flux capacitors.
Right next to the box of Plutonium.
The best explanation of antennas.
Thanks Glen. -Derek
Split videos as you feel you need.
❤❤❤
J is not displacement current, mu0 de/dt is. Also an E field can exist without a B field, just not a solenoidal one.
Thanks for your comment. I think the viewer understands that when we're speaking about E and B fields coexisting, we're referring to an electromagnetic wave.
@@AmRadPodcast 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.
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.
Radiation is complicated. A static charge produces a field that is static. An uniformly moving charge produces a changing field which is non-radiating (it doesn't transfer power at infinity). An accelerated charge is able to radiate (transfer power at infinity). I do not fully understand this although I teach this at the UG level. I can follow the math but I still don't grasp the "why"!
Thank for your video, but vital info seems to be missing.
As in most rf videos.
Still a good video though
That is great to hear! I didn't want this to be the same format as most other antenna videos.. and I've watched quite a few. Make sure to come back for part II and maybe some of the missing vital information will be there. -Derek
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".
Bro… I’m a mechatronics technician but this is next level 😳 radio frequencies are cool!
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.
U cut it there?!
Yeah, sorry had to cut it somewhere - unfortunately, that was the most natural place. However, if you hit the link in description, the full talk with Sterling is there. -Derek
School never end? We thought we've left school, but no!
Never stop learning! Pull up a chair. 😁
Halfway decent
Integral? I do enjoy a good calculus pun.
e to the x was at a party for math functions and tried to integrate. It didn't make any difference.
Ha! My wife says pi r squared. I say they're round. -Derek
@@AmRadPodcast Pi and 22/7 were roommates, and they constantly got on each others' nerves, as roommates are wont to do. At one point, 22/7 asked Pi "Why do you have to be so irrational?!" Pi retorted "Stop repeating yourself!"
@@petersage5157 😆
why do you look like Tony stark ??
Why do you not know what Robert Downey Jr looks like??
12:38 100 mHz with a wavelength of 3 meters is insane
Something being 9 feet long with 100 million oscilation per second is simply not ok
Well it should be 99.93 MHz to be more precise, but 100 MHz is fair enough!
c/f = lambda
(3x10^8 m/s)/(1x10^8 cycles/s) = 3m per cycle
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.
RF is all cool till you get to my house and then it falls apart.. lol radio radio don't work
In vacuum 😂
Thank you for the video .. but well, sorry Sterling but the black magic is still black magic :( ...
the key thing to start with for the journey of understanding this magic is: "Kinks" ..
but guess what, although I've went through the journey of "digesting" what really happens for the em wave to propagate, I'm unluckily still not satisfied :( ...
Typical, bait you in then here’s the subscription fee.
You really didn't explain it in a way most people would understand. Try this: Radiation Antenna: As the electrons flow toward one pole of the antenna, electrons are flowing away from the other pole of the antenna. Although there is no electrical connection between the poles of the antenna itself, there is an "electromagnetic" connection and the Amplifier "driving" the antenna "thinks" there is a connection, so it thinks current is flowing (which it is but not by direct electron flow). It's sort like of how a capacitors allow AC to pass through even though there is no electrical connection between the two leads - But that is electrostic fields. Now, because current is flowing through the antenna, a magnetic field builds up perpendicular to the poles. So, as the electrons start to flow from 0 to max, the electric fields builds with the poles as the magnetic field builds across the poles, then as the electron flows from max to 0, the two fields diminish. Then the polarity changes and the electrons flow into the other pole while electrons flow out of the other pole. This cause the fields to reverse. As the current flipps back and forth (alternates current AC), so to the fields. This causes them to move away from the antenna as energy being "radiated" as an electromagnetic wave. Think of this. A circuit has to have a send and return path for current to flow, at the other end is a load (where electrons do their work, say convert to heat). If we design our circuit wires properly, the energy flow into the load will be optimal and thus max energy transfer. We call this impedance mating, if the driver, wires (transmission lines), and load all have the same impedance, the max energy will transfer. That's what antennas do, the impedance match the driver, transmission line, and the antenna itself to free space (air on earth). What is key about electromagnetic (EM) waves is, once an antenna converts electron flow into a radiated electromagnetic wave, no return path to the receiver is needed, that EM wave will then couple into the receiving antenna and cause electrons to flow back and forth in it, but at a much less strength (magnitude). Just like light diminishes by the inverse square law, so do propagating EM waves. Why the connection? Light propogates as an EM too, just much higher frequencies than radio waves.
Assuming earth is sphirical?
Really? 😂
Talks waaay too fast 👎to be useful
please speak slowly. because your videos are watch by people around world, not only english speaking people. please reduce your speech speed by 30 percent. Please
Good thing you tube offers the option to change playback speed.
With the playback speed control, still not good speech. Better, the speech in you tube video be reduced by a content creator.
Haha.. assume “your” earth is spherical in nature.
where do you guys make your money? you barely get any RUclips views, you don't sell anything, there's not that much activity on your forum, ... is this just for you people to add to your resumes? i mean, great production values, but i'm just wondering what's in it for you, and why, despite seemingly working hard on this, why you're not working on getting more reach?
... Element 14 just seems kinda weird to me...
Element14 is part of the big electronics components retailer Newark, which is I believe owned by Avnet. Avent also own Farnell in the UK
Thanks, we're glad to hear that you believe element14 presents content, and the content by the video creators is worth sharing and we'd be glad to see it shared further!
element14 presents is a part of the element14 Community as we're sure you've seen the links to the Community site, and it's easy to think that not a lot happens there, perhaps because there are so many different groups and categories, but there's more than simply one forum, there're many forums, comments, blog posts and documents to get involved with, and you're welcome to take part.
As another mentioned, the element14 Community is a part of Farnell, a multi-national electronics distribution company, and Farnell is a part of Avnet. Frankly we don't typically post our products directly as links on our videos because we've responded to feedback that people don't want to see that. We can start doing that again if it's what people want, but really we want people to be a part of the Community and help Engineers and Makers to produce great projects, to inspire them, and learn and share their knowledge with others.
Thanks for the comment and taking part.
@@7alfatech860 They also own CPC in the UK too, together the organisation is probably the biggest around!
@@petersheldon3558 Didn't know that.
Just want to clarify, I really enjoy the videos they put out on this channel, esp Derek and I have not noticed any commercial bias
@@7alfatech860 I really enjoy them too, it makes a change from the video's which just want to sell you something, hopefully they keep up the good work as I'm looking forward to the next installment.
No, you don't say EM waves do not obey the wave equation. You say the wave equation describes the behaviour of EM waves.
Don't split videos up into parts.
Why not ?
I tell you why
RUclips recommends that video/clip from 8 - 17 min are the most viewed
Prefer 2 part videos. It creates an intermission. Cook up a batch of popcorn. Relax with an opera glass of champagne before scrambling your brain again in the second half. Play tackle football. Whatever you want to do
@@franciscoosuna259Pause works
@@mohammedissam3651 But stupid cat videos are the most viewed.