Sure , here's the FIRST one.

EDIT: Hey, is the reason they used a parallel LC circuit is because the Q is highest in a parallel circuit, and lowest in a series LC circuit?

I'm doing some research and I came across these two equations:

Q(series) = X (inductor) / R(series) --> resistor is in series with the inductor

Qparallel = R (parallel) / X (inductor) --> resistor is in parallel with the inductor

So we need to have maximum Q, so therefore the Q parallel makes more sense since my inductor is 72 uH, and if my resistor is 1 ohm then its a really huge number for Q parallel no?

But if I'm not mistaken, doesn't added resistance only shift the resonant frequency higher/lower depending on if you put it in series with the capacitor or inductor?

 

From what I understand you don't.
By Maxwell's equations at any point where you have a time varying E field you get a B field and vice versa and hence you will have a propagating wave.

The fields vary depending on distance from the source, where nearby you will have predominantly B or E and as you move further away it turns into a plane wave (by appropriate attenuation of the stronger field, the plane wave component should still exist even near by)

It becomes a question of radiating efficiency I guess, where to radiate effectively the structure needs to be approaching a wave length in size.

I think I have to disagree with that statement, you have magnetic flux in many cases without an electric field, just as you can have an electric field without a magnetic field. Prime example are coils and capacitors. I believe you could also point to a tesla coil as an example for extreme electric field without a corresponding magnetic field, although it is created with a magnetic field.

I think a MRI machine could be a good example for the magnetic effect, the RF radiation involved is from the atoms bounding back to their normal orientation after the magnetic field is turned off, but the machine itself creates no RF.

 

I think I have to disagree with that statement, you have magnetic flux in many cases without an electric field, just as you can have an electric field without a magnetic field. Prime example are transformers and capacitors. I believe you could also point to a tesla coil as an example for extreme electric field without a corresponding magnetic field, although it is created with a magnetic field.

I think a MRI machine could be a good example for the magnetic effect, the RF radiation involved is from the atoms bounding back to their normal orientation after the magnetic field is turned off, but the machine itself creates no RF.

I think that means you disagree with Maxwell's equations though (unless you're only talking DC), they're pretty explicit and apply to all points in space.
http://en.wikipedia.org/wiki/Faraday's_law_of_induction#The_Maxwell-Faraday_equation
http://en.wikipedia.org/wiki/Ampère...law:_the_Maxwell.E2.80.93Amp.C3.A8re_equation

I don't agree with your examples. If there is a voltage there is an electric field because they are aspects of the same thing. If there is a current there is a magnetic field because they too are related.
Even if you ignore B creating E and E creating B (which you can't if you accept propagation at all) you will still have B and E together in both transformers and capacitors. This B and E will be related by the appropriate equations of capacitors and transformers.
So in a capacitor the current will lead the voltage by 90 degrees and will be the same frequency, meaning you will have B field leading E field by 90 degrees at the same frequency.

I also recall one of my professors (whose research is in meta-materials) explicitly telling us capacitors must have magnetic field.

 

Nope, I think you are misinterpreting them. Electromagnetic radiation is not the same as magnetic or electric fields. They can be treated as separate entities, and I posted concrete example of how it was done. Coils and capacitors generate the fields separately all the time. An antenna is a transducer that merges the two, but having electric and magnetic fields linked is not a given unless you create the right conditions.

Maxwell's equations don't dictate that electric and magnetic fields have to be linked, it is a mathematical description of what they look like if they are linked, and their relationship to each other in that case.

Capacitors have a magnetic field only as a parasitic effect, anytime you have current flowing through a wire you will have some inductance, but it negligable, as high as thousands of orders of magnitude less than the capacitance. You also have a similar opposite effect in coils, there is always some minor capacitance in a coil causing self resonance, but none of that applies in this case.

Transformers are another device that uses only one field (magnetic) in alternating mode. There are many examples of using one field only in devices and electronics. Before you focus on the iron core, there are lots of examples of open air transformers, they aren't as efficient but they use magnetic, not RF, coupling.

This is why there are two fields, not one. If you couldn't have one without the other, they wouldn't be two entities.

 

Nope, I think you are misinterpreting them. Electromagnetic radiation is not the same as magnetic or electric fields. They can be treated as separate entities, and I posted concrete example of how it was done. Coils and capacitors generate the fields separately all the time. An antenna is a transducer that merges the two, but having electric and magnetic fields linked is not a given unless you create the right conditions.

Maxwell's equations don't dictate that electric and magnetic fields have to be linked, it is a mathematical description of what they look like if they are linked, and their relationship to each other in that case.

Capacitors have a magnetic field only as a parasitic effect, anytime you have current flowing through a wire you will have some inductance, but it negligable, as high as thousands of orders of magnitude less than the capacitance. You also have a similar opposite effect in coils, there is always some minor capacitance in a coil causing self resonance, but none of that applies in this case.

Transformers are another device that uses only one field (magnetic) in alternating mode. There are many examples of using one field only in devices and electronics. Before you focus on the iron core, there are lots of examples of open air transformers, they aren't as efficient but they use magnetic, not RF, coupling.

This is why there are two fields, not one. If you couldn't have one without the other, they wouldn't be two entities.

I thoroughly disagree.

I did not say that electric and magnetic fields are the same as an EM wave, I said all time varying electric and magnetic fields will create an EM wave.
I already made the distinction between near and far field. Look in an EM textbook which derives the fundamental antenna equations and you'll see you get a summation of terms, both the ones you'd expect from statics and a plane wave term. They differ in magnitude based on distance to the source, hence the distinction between near and far field.

What are these special conditions that allow E and B to be related?
Any piece of wire of any shape is a decent antenna at some frequency.

Your interpretation would require two types of E field for example, the kind that can induce an H field and the kind that can't. Maxwell's equations apply to all points in space in all situations.
You listed (not explained) examples of near field situations where you only need to look at one type of field to derive the basic functionality. This says nothing of the reality and is not a concrete example of anything.

The second you insert a time varying term into equations derived from statics they become referred to as 'quasi-static'. Basically it means you're ignoring propagation and pretending the equation didn't change.

I would suggest looking at something like this site:
http://web.mit.edu/hychenj/OldFiles/MacData/afs.course/6/6.013_book/www/chapter3/3.0.html

It's pretty dense but it discusses the approximation of ignoring the interacting terms.

So again, there is a very clear difference between simplified practical calculations and the more detailed reality.
As to the "two fields, not one" issue I've already emphasized "time-varying" several times. There is plenty of reason to individually define them even if they induce one another.

 

So where is the RF for an electromagnet or transformer? You're argument is very weak at best. Most high power electromagnets in junk yards use AC to lift aluminum and other non ferrous materials.

An antenna will convert RF into electricity and visa versa, which is not a coil nor capacitor. You can use a coil and cap to tweak the electrical length of antenna wire, but they are not RF radiators.

Again, these are two fields, not one, you can combine them with a antenna, but they don't come that way. You are effectively saying they are one field, which is easily proven wrong if you don't reject all evidence to that you don't agree with. I've shown around 10 or so examples, even if you with to reject the evidence. Reality has a way of showing through.

You've even stated a capacitor is a coil, which is a major reach (I assume you have done labs with capacitors). I've generated oscillating magnetic fields without RF, and I've built my share of transmitters. Telling the difference isn't hard.

More examples include induction heaters (pure oscillating inductance). You have yet to disprove any of my examples, you just argue that it ain't so without followup.

BTW, where is the RF energy in a transformer, a pure inductive device?

 

Explain the difference between an antenna and a piece of wire that determines whether Maxwell's equations apply or not.

I have not stated a capacitor is a coil, that is a complete twist on your part. The existence of a small magnetic field inside a capacitor with a small propagating term while immersed in a strong electric field does not create an inductor which has magnetic field as the dominant component. Again you are ignoring the distinction between existence and a dominant behaviour.

Did you look at my link at all?
http://web.mit.edu/hychenj/OldFiles/MacData/afs.course/6/6.013_book/www/chapter3/3.3.html

This example is a disc capacitor and a discussion of ignoring the magnetic induction term. You'll see the relevance of the term depends on the frequency of excitation - i.e. how large the system is compared to the wavelength. This is what near and far field is about.

I hate to drag him into this but read steveb's comments in this other thread:
http://forum.allaboutcircuits.com/showpost.php?p=250003&postcount=5

You have not put any reasoning in your argument, you are simply saying how you think it is, backed up by invalid experiments. They are invalid because as I keep saying there is an obviously dominant field and there are conditions for a structure to be a good radiator.

 

A theory is nice (I reviewed it, but math is not my strong suite), but you have consistently ignored a large sample of data that directly contradicts yours.

Do you understand Tesla Coils? Or lightning? The field strength that create these phenomena is measured in V/cm. This is not an RF measurement. Measurement of these fields is Tesla. If one could not exist without the other then they wouldn't be two fields, but one.

Coils generate large magnetic fields, yet they can exceed 90% efficiency. The phenomena is 100% magnetic. Ditto with electromagnets using AC.

In both these examples the fields stand alone. Try explaining them, not ignoring them. Math can reflect reality, but reality supercedes theory. One counter example is all it takes. I am not arguing Maxwell's equations, just your interpretation.

In any RF field the EM radiation is 50%/50% and at right angles to each other. This is not true of any of the devices I mentioned before. Try looking at the real world and applying math to it instead of trying make reality fit the math.

 

Okay, so, to cut you two off from arguing and focus on me hehe, let me ask you two this:

If my parallel LC circuit oscillates back and forth at their resonant frequency, this should only back-and-forth produce a magnetic field from the coil right? I mean, the electric field is confined in between the plates of the capacitor, no? I thought electric field radiation is what gets the feds at your door and also harms biological organisms. But magnetic fields are safe, and for near-field power transfer. Please tell me all your knowledge on this topic. I want to create a very strong magnetic field with my LC circuit with minimal current input from my AC source, since at resonance this should build up to a much larger current value, right? And which orientation (series or parallel) and what else should I do to make this happen so I can induce a strong current into my secondary coil from the strong magnetic field of my primary coil?

 

Hello,

Take a look at this PDF:
http://www.odyseus.nildram.co.uk/RFMicrowave_Theory_Files/Oscillator_Resonators.pdf

It is a link from the tutorial page with RF microwave theory:
http://www.odyseus.nildram.co.uk/RFMicrowave_Theory_Page.htm

@Bill_Marsden:
About the MRI:
There is a static magnetic field in the MRI.
There is also a dynamic magnetic field to address the point of intrest.
There is a RF puls that moves the atoms in the bonds.
As the atoms go to their rest position again they "transmit" a RF signal that shows how the bonds are attached.


Bertus

 

This I knew, my point was the RF field did not generate the RF directly.

To CokeZero,

Your analysis is basically correct. Antennas are transducers, if an antenna is attached to a tank circuit the tank will resonate from the RF recieved in the antenna. Interestingly, antennas can also be resonant by a different mechanism.

Any RF signal connected to an antenna will radiate, tank circuits can help this mechanism. To radiate you need an antenna.

 

This I knew, my point was the RF field did not generate the RF directly.

To CokeZero,

Your analysis is basically correct. Antennas are transducers, if an antenna is attached to a tank circuit the tank will resonate from the RF recieved in the antenna. Interestingly, antennas can also be resonant by a different mechanism.

Any RF signal connected to an antenna will radiate, tank circuits can help this mechanism. To radiate you need an antenna.

Hmm...okay. So does an antenna have any particular shape or size or any other special property? I mean, I did some searching on it, and all it is just some thing that takes electrical signal and converts it to Radio Frequency. However, I can't have that Bill...I need to do this only with fluctuating magnetic field from my primary coil to induce a current into my secondary coil. Is this possible or must I have an antenna and use RF radiation?

 

all it is just some thing that takes electrical signal and converts it to Radio Frequency

Before you try to understand the answer to your questions, try to get a few fundamental ideas straight.

Most of these ideas have already been answered in this thread, you need to adjust your thoughts to take account of these answers.

The antenna does not convert anything. If the electrical signal is not already oscillating at radio frequency the antenna will not convert it.

The point is that to launch a coherent signal into a propagating medium you need to match the impedance of the launch device (antenna) to that of the medium or the signal will die away very quickly due to damping, rather than propagate.

This is the purpose of the antenna, to match the impedance of the electrical circuit to that of the propagating medium (air or free space) as far as possible.

Whatever resonant circuit you choose, you will also need an amplifier to replace the energy you are taking out of it otherwise again the signal will die away.

 

What do you mean by radio frequency? Is it some frequency that must be in the radio spectrum or the natural resonant frequency of LC circuit?

Also, I can't use an antenna. This will only radiate my oscillating signal into the air (medium), and I can't have that happening. The whole point of this witricity project is to use magnetic coupling, not through RF radiation. I know RF radiation works and its not that involved, but it's harmful (EM radiation) and can get you into trouble (propogating in an illegal (allocated) band). I'm not sure if I'm not getting my ideas across to you guys or you guys are not understanding me, but I need to know the difference between a series and parallel LC circuit in terms of magnetic fields and which one uses the least power. Which one will produce a stronger magnetic field? It can't be the same because my simulations are not showing the same current/voltage readings.

In my two simulations below, you will know what I am talking about.

The first circuit diagram shows a series connection and the voltage is in the kV magnitude, which is really really high. Also, the current is extremely high, but I also read somewhere that as soon as you place some load into the circuit the current dies out and becomes very very weak. I need you guys to please clarify this and why it happens.

In the second diagram, I have a parallel tank circuit. In this diagram, it shows that the current drawn from the generator is very very minimal, but the current in the inductor is really high, in fact, 25,000 times higher than what is being drawn out of the generator (1.59 / 61.344 E-6). As far as I read, this is supposed to happen because tank (parallel) LC circuits are used for current magnification.

Please confirm and add to these results .I need to build an extremely well foundation before I embark on any physical building of any models. Once again, thank you all for your contribution. I am very happy. Just a little more knowledge please!

 

I hate to disillusion you in your goal, but it is not achievable using your current approach.

Firstly effective transfer of power depends upon efficient magnetic coupling between source and receiver. In a normal magnetic field the energy spreads out as you go further from the source. In fact the energy density reduces increasingly rapidly according to the inverse square law. This is why special core materials are used for transformers - to concentrate the magnetic flux where it is wanted. You would need to find/discover an equally efficient channeling/focusing mechanism over the transmission path.

As regards to the simulation you are showing, you have not taken the phase into account. The actual power = voltage x current x cosine phase. This cosine will be nearly zero in a resonant circuit. Theoretically it is exactly zero, and the voltages are infinite, but real world components don't quite achieve this.

 

A theory is nice (I reviewed it, but math is not my strong suite), but you have consistently ignored a large sample of data that directly contradicts yours.

Do you understand Tesla Coils? Or lightning? The field strength that create these phenomena is measured in V/cm. This is not an RF measurement. Measurement of these fields is Tesla. If one could not exist without the other then they wouldn't be two fields, but one.

Coils generate large magnetic fields, yet they can exceed 90% efficiency. The phenomena is 100% magnetic. Ditto with electromagnets using AC.

In both these examples the fields stand alone. Try explaining them, not ignoring them. Math can reflect reality, but reality supercedes theory. One counter example is all it takes. I am not arguing Maxwell's equations, just your interpretation.

In any RF field the EM radiation is 50%/50% and at right angles to each other. This is not true of any of the devices I mentioned before. Try looking at the real world and applying math to it instead of trying make reality fit the math.

I do not accept your sample of data or your supposed reality. Unless you specifically look for it you won't find it. There's really not much to explain - I don't believe you measured both E and H taking into account the many orders of magnitude difference between them.
Inductors and transformers are well known to radiate and cause EMC problems. If radiation required some very special things you probably wouldn't need legal requirements on radiated emissions. Where is the antenna in a computer or a vacuum cleaner that makes them fail the testing?

Your "two not one" argument is entirely flawed. Each component clearly has a different effect and a different fundamental behaviour. The fact that they are inexorably linked in some way when they are time-varying is another point entirely.

I can still entertain your question - an electromagnet will be using frequencies of a few kilohertz at most while be physically smaller than a few meters. The wavelength of 300 kHz is 1 kilometer with lower frequencies even larger. The electromagnet cannot be a good radiator at these frequencies because it is orders of magnitude too small.

Your question of efficiency - consider stored energy in both E and B field.
Stored energy and power are related to the square of the magnitude. If the magnitude of your E field is 1/10th (= 0.1) of the 'equivalent' H field (= 1) it will have 1/100th of the energy, or you have about 99% efficiency.
All your experiments would need some pretty precise (and practically useless) measurements to prove me wrong.

There's some of my answers, now answer some of my mine:

a) What changes a piece of wire into an antenna such that Maxwell's equations suddenly apply?
b) How do you explain away your requirement of having two kinds of E field and two kinds of H field? If Maxwell's equations only apply sometimes then there must be a fundamental difference in the field itself.

I do not make reality to fit the math but rather try to make sure they work together... you have several gaping holes in my opinion.

Lightning interferes with radio for example. Ever notice that the station can crackle briefly when a strike happens? That would mean lightning just induced something in your antenna. Lightning interacts with antennas so what's the explanation? Do Maxwell's equations suddenly kick in because you called it an antenna?
Even this Wiki article keeps talking about RF signals and detection kilometers away:
http://en.wikipedia.org/wiki/Lightning_detector

Why is this an antenna and not an air core coil?
http://farm3.static.flickr.com/2169/2458190759_750bc4c078.jpg

 

I hate to disillusion you in your goal, but it is not achievable using your current approach.

Firstly effective transfer of power depends upon efficient magnetic coupling between source and receiver. In a normal magnetic field the energy spreads out as you go further from the source. In fact the energy density reduces increasingly rapidly according to the inverse square law. This is why special core materials are used for transformers - to concentrate the magnetic flux where it is wanted. You would need to find/discover an equally efficient channeling/focusing mechanism over the transmission path.

As regards to the simulation you are showing, you have not taken the phase into account. The actual power = voltage x current x cosine phase. This cosine will be nearly zero in a resonant circuit. Theoretically it is exactly zero, and the voltages are infinite, but real world components don't quite achieve this.

What do you mean by "phase account"? I've seen these demonstrations been done on youtube and other websites and their circuits are almost identical to mine. I'm pretty sure they don't know what phase accounts are either. Mind telling me what it is and how it affects my resonant LC circuit? I'm not going to build this model just yet, I need to collect as much information on it as possible so I can build a really good one and know what I'm doing.

What do you mean by "channeling" path? How can I do this? The M.I.T group used evanescent coupling to "tunnel" their power over 2 meters, can you please tell me more about it?

And Bill Marsden:

I quote you from a long time ago:

Several things that I can see. You're transmitter is a series resonant circuit, which can work, but I suspect a parallel resonant circuit would be much more efficient.

Why do you suspect that Bill?

 

I do not accept your sample of data or your supposed reality. Unless you specifically look for it you won't find it. There's really not much to explain - I don't believe you measured both E and H taking into account the many orders of magnitude difference between them.
Inductors and transformers are well known to radiate and cause EMC problems. If radiation required some very special things you probably wouldn't need legal requirements on radiated emissions. Where is the antenna in a computer or a vacuum cleaner that makes them fail the testing?

Your "two not one" argument is entirely flawed. Each component clearly has a different effect and a different fundamental behaviour. The fact that they are inexorably linked in some way when they are time-varying is another point entirely.

I can still entertain your question - an electromagnet will be using frequencies of a few kilohertz at most while be physically smaller than a few meters. The wavelength of 300 kHz is 1 kilometer with lower frequencies even larger. The electromagnet cannot be a good radiator at these frequencies because it is orders of magnitude too small.

Your question of efficiency - consider stored energy in both E and B field.
Stored energy and power are related to the square of the magnitude. If the magnitude of your E field is 1/10th (= 0.1) of the 'equivalent' H field (= 1) it will have 1/100th of the energy, or you have about 99% efficiency.
All your experiments would need some pretty precise (and practically useless) measurements to prove me wrong.

There's some of my answers, now answer some of my mine:

a) What changes a piece of wire into an antenna such that Maxwell's equations suddenly apply?
b) How do you explain away your requirement of having two kinds of E field and two kinds of H field? If Maxwell's equations only apply sometimes then there must be a fundamental difference in the field itself.

I do not make reality to fit the math but rather try to make sure they work together... you have several gaping holes in my opinion.

Lightning interferes with radio for example. Ever notice that the station can crackle briefly when a strike happens? That would mean lightning just induced something in your antenna. Lightning interacts with antennas so what's the explanation? Do Maxwell's equations suddenly kick in because you called it an antenna?
Even this Wiki article keeps talking about RF signals and detection kilometers away:
http://en.wikipedia.org/wiki/Lightning_detector

Why is this an antenna and not an air core coil?
http://farm3.static.flickr.com/2169/2458190759_750bc4c078.jpg

We will agree to disagree, you go ahead and ignore reality and all the devices I've presented that work using only one field. I'm done wasting my time on this distraction.

 

Guysssssssssssss ........I am in great pain here!!!!!!!!!!!!!!!! The articles and the AAC textbook don't answer my questionssssssssssss.............please read MY posts and try to give me some answersssssss. Thank you

 

The antenna does not convert anything. If the electrical signal is not already oscillating at radio frequency the antenna will not convert it.

The definition of an antenna from Wiktionary

Noun

Singular
antenna

Plural
antennae or antennas

antenna (plural antennae or antennas)

1. (plural: antennae) A feeler organ on the head of an insect, crab, or other animal.
2. (plural: antennas) A device to receive or transmit radio-frequency signal by converting electromagnetic radiation into electrical signal.
3. (plural: antennae) The faculty of intuitive astuteness.

An antenna is a transducer, it converts one thing into another. It is not a simple piece of wire, it is a device, made for and tuned to the frequency it converts. A high frequency RF electrical signal is required of course, but it is not electromagnetic radiation without the antenna.

We frequently get people wanting to use RF for power, it won't work. The power levels are way too low, in the microwatt level or much less. There are exceptions, such as beamed microwaves or better, such as masers. Most of the power can be recieved by the antenna (there are always losses) and converted to an electrical signal and then rectified. It's been mentioned before, but this approach can have its own dangers.

Both RF and magnetic coupling suffer from the inverse square law in an omnidirectional signal. If wireless was simple it would have been done already. You aren't going to get simple answers, you are going to have to work on this yourself, no one else can do it for you. Lots of studying is going to be required.