Faraday's law; do E and B fields cause each other?

[FrediFizzx]

There is a never ending debate about whether E and B fields cause each other which I claim that they don't cause each other and changes in one don't cause changes in the other. Faraday's law is one source of the confusion as it doesn't show sources that caused the E and B fields in the first place.

Now on the sci.physics.electromag UseNet group, Dr. Paul Kinsler is taking the stand that his paper proves that spatial changes in an E field can cause temporal changes in a B field. More discussion is here.

More coming about this topic...

[scibenj]

The question of causality in electromagnetics has recently received renewed attention in part due to the late professor Jefimenko who examined the causality of Maxwell's equations and noted that the widely held belief that E and H fields cause each other is false. And that means that Faraday's law is bogus. That something was wrong with Faraday should have been obvious from the fact that a changing magentic field "apparently" could induce an emf in regions of space where the magnetic field was zero (eg. outside of a toroid). Hence the search for a mechanism to "explain" how a changing magnetic field created an emf is stalled.

But how does causality work anyway? Jefimenko notes that if two events take place at the same time but at different locations in space they CANNOT cause eash other. The reason being that information must travel faster than light to create the situation. But what Jefimenko did not talk about was the case when two events (like E and B) take place at the same point in space rather than at two different points. Now the distance is zero and that implies a rather indeterminate situation with regard to our previous argument. Since now one might suggest that information can be simultaneous because it has to travel no distance. Also note that in Jefimenko's equations the distance from source to observation point, r, is in the demominator so any attempt to make r = 0 makes the whole relation undefined.

And this is where the Kinsler paper enters. But I wish to point out a problem here. And that is the difference between what I'd call "real" quantities (which means that they actually exist in materiality as opposed to say "real numbers" which in spite of the name are pure fantasy) and mathematically derived ones. Here's what I mean. Take a particle in space. If you move it about in time your can create a function of it's position in space vs time. This is all real stuff. The partical is real material having mass, space is there holding us all and we all are subject to the passage of time. So the function is a description of what we term real objects doing real things.

But now consider another function. This is the velocity of the particle. We use the concept of velocity so much it SEEMS like it's a real thing, but is it? Velocity is a rate of change. It is related to how far the particle will move in a given (short) span of iime. It is basically the slope of the above function. But from a causality viewpoint is it a "real" thing? I say it isn't because if I give you a point x,y and ask for the velocity of the particle you can't give it to me with ONLY that information. Because velocity is the RESULT of a mathematical operation, you must perform that operation to find it's value and the operation requires MORE than just the present position of the particle. It requires information from either the past, or the future or both as well.

Since the operation is such that if the displacement function is regular, the operation can be performed with only information from the past to give velocity at the present time, one CAN argue that causality is NOT violated as the future data is not used. Hence we can say that indeed the displacement of a particle CAUSES it's velocity! And it seems reasonable.

But velocity is a derived quantity. But if we now take E and B and a similar relationship there seems to be a problem. And that problem is that in this case BOTH E and B are REAL quantities. Both are force fields capable of creating action. So which one is the real field and which one the derived mathematical expression? It can't be separated because it can work either way. So this seems to say that an emf derived from a changing B field mathematically is NOT the same thing as the E field found in space creating the currents when a B field changes. Jefimenko's explanation is that both fields are created by charges and currents somewhere else and are causal with those and are simply related to each other because they come from the same source. This makes sense.

But Jefimenko has stated point blank that even when two simultaneous events are at the location r = 0 then they still cannot cause one another, but he never proves this premise nor indicates any proof or arguents for it. Instead he talks about our above velocity case being causality by "definition". which he accepts. but in any event there seems to me to be a gaping hole here where Jefimenko has simply made a statement without proof and Kinsler has just gone ahead with mathematics ignoring the problem of real vs calculated quantities.

It seems a closer look is warranted to clarify these issues.

[FrediFizzx]

The question of causality in electromagnetics has recently received renewed attention in part due to the late professor Jefimenko who examined the causality of Maxwell's equations and noted that the widely held belief that E and H fields cause each other is false. And that means that Faraday's law is bogus.

I wouldn't say that Faraday's law is bogus; I would say that interpretations of it by some people are bogus. Which may be somewhat understandable since it is missing information necessary for a correct interpetation. What is missing is(are) the source(s) that created the fields E and B in the first place. Here is Faraday's law in differential form with the missing information included.



Where square brackets are retardation symbol, r is the distance between the field point x, y, z and the source point x', y', z'(volume element dv').
This is from Jefimenko's book, "Causality Electromagnetic Induction and Gravitation". He had them separate though and never did put them in the above form. So we can see what the true cause is for the E and B fields in Faraday's Law.

Now, all the plain differential form says is that when you have a changing in time B field, you will have a changing in space E field. It says nothing about one causing the other one or causing changes in the other one. The big question to ask here is why and how? But the answer to that is probably a topic for another thread.

[scibenj]

I use the word "bogus" with regard to Faraday's law not meaning that it gives the wrong answers (in most (but not all) cases it gives correct answers), but rather from a philosophical viewpoint. There is redundancy all over electromagnetic theory that gives "correct" (meaning agree with measurements) answers, but are clearly philosophically questionable.

Faraday's law being one. Looking at your equation what happens is people take the LEFT side and see the equality relating E and B and assume that E is "causing" B and vice versa. We observe the retarded quantity is on the right, so E and B in that equation occur simultaneously. So now the question arises are they "causing" each other. In my post I discussed this noting that since the distance is zero, the answer is not as trivial as it is in the case where there is a distance separation.

And furthermore I again point out that in this case both E and B are REAL objects, force fields in this case producing real forces as opposed to some mathematical quantity derived by a transfrom (like say acceleration or velocity).

Even in the case of velocity I have tried to argue (unsuccessfully) that velocity at a given time requries information for OTHER times. But since for regular functions the past is sufficient, that argument can't be used to disprove causality of derivative funtions where the derivative is continous. Truth is that velocity IS INDEED "created" by the motion of the particle hence F(x,y,z) "creates" V(x,y,z). But the catch is that velocity isn't real. It's simply a mathmatical transform quantity.

But E and B are real measureable quantites. So now the derivative relationship takes on a new light. And one has to ask if the apparent causality is real or is it just one more electromagetic redundancy?

So far I have seen no credible proof of Jefimenko's assertion that two actions that take place simultaneously cannot cause each other even if they occur at the same point. One such proof would be to allow fields with discontinuous derivatives. That immediately proves Jefimenko's premise. But while in mathematical fanatasy I can allow anything I choose, in reality it is not clear if fields REALLY can have discontinuous derivatives.

[_Jim]

I'd like to know how the E and B (or H) fields 'line up' after radiation from a 1/2 Lambda dipole.

It would seem axiomatic that they are in-phase while propagating in free space yielding 377 "Ohm" Z of free space, but, 1/4 wave away (and maybe even 1/2 wave away) from a dipole the fields appear to be in phase quadrature.

At the present moment I am also of the mind that the 1/2 wave dipole (and 1/4 wave vertical) achieve radiation via the magnetic field and less so due to the electric field. I have just not been able to conjure up the scenario of fields in my mind which allow proper induction of EMF into a vertical (or dipole) from a propagating E-field.

I have spent the last couple of years working with a variety of RF radiators, ranging from 1/4 wave tuned Edginton loops, the (so-called) EH antenna, and the Robert Vincent DLM (Distributed Loaded Monopole) antenna. Some of these I have compared against a dipole in real time, using two radios and simultaneously transmitting signals to the WSPR network of cooperative receivers operating around the world, since it is so difficult to schedule real 'range time' on a test range large enough to accommodate 160 meter through 40 meter HF antennas (this last part is meant to be 'a pun').


_Jim

[_Jim]

I'd like to engage someone on this subject before moving onto another item which I discovered late last year. But,if we cannot even converse on something as established as the elementary 1/2 wave dipole or 1/4 wave monopole, there is little point in bringing forward anything new on another type of antenna in the way of an very acute observation on its characteristics in the field.

_JIm

[_Jim]

I would like to enter into the record an (almost) exclusively E-field antenna (in the near or reactive field area) of size 2 to 5% wavelength as contrasted with a small (< 1/5WL) loop (magnetic field dominant in the near or reactive field) or even the traditional 1/2 wave 'dipole' antenna.

http://trputec.com/s52st/bipol/9a4zz_bipol_antena.pdf

Note the on the second sheet (page 19) in FIgure 4 the depiction of the radiation (or reception) pattern of this antenna; I can confirm in my own experiments the same 'response' pattern.

Note well, the antenna response or 'pattern' is directly _opposite_ that of a traditional 1/2 wave dipole antenna. That is, maximum response (or radiated energy) occurs _end-on_ rather than _broadside_ as one has with the usual, traditional 1/2 wavelength dipole.

I am asserting that the antenna described in the above pdf document works on the principle of differential electric field 'induction' as an impinging EM wave encounters this "Bipole" E-field antenna (as described in the above pdf document). This will be as opposed to the singular (non-differential) 'magnetic' induction of current in a standard 1/2 wavelength dipole antenna.

_Jim

[Q-reeus]

As A.Shadowitz pointed out clearly on e.g. bottom of p388 of his 1975 textbook 'The electromagnetic Field', it is a mistake to think that the Maxwell-Faraday law ∇×E=-∂B/∂t represents a cause-and-effect relationship. Rather, both LHS and RHS are effects and the real cause in every case is electric charge in arbitrary motion - in accordance with the Lienard-Wiechert potentials.
A well respected authority who got it doubly wrong conceptually was R.E.Collins, in his tome 'Foundations for Microwave Engineering'.
He illustrates a supposed 'causative linkage' between E and B fields that has the wrong phase relationship - incorrectly having mutually transverse (to each other and to propagation axis) components of E and B fields in phase quadrature propagating down a rectangular wave guide. Such unfortunately is the reality of 'weight of authority', this blunder in an otherwise excellent textbook remained uncorrected through two time-wise widely separated editions!

[Q-reeus]

I would like to enter into the record an (almost) exclusively E-field antenna (in the near or reactive field area) of size 2 to 5% wavelength as contrasted with a small (< 1/5WL) loop (magnetic field dominant in the near or reactive field) or even the traditional 1/2 wave 'dipole' antenna.

http://trputec.com/s52st/bipol/9a4zz_bipol_antena.pdf

Note the on the second sheet (page 19) in FIgure 4 the depiction of the radiation (or reception) pattern of this antenna; I can confirm in my own experiments the same 'response' pattern.

Note well, the antenna response or 'pattern' is directly _opposite_ that of a traditional 1/2 wave dipole antenna. That is, maximum response (or radiated energy) occurs _end-on_ rather than _broadside_ as one has with the usual, traditional 1/2 wavelength dipole.

I am asserting that the antenna described in the above pdf document works on the principle of differential electric field 'induction' as an impinging EM wave encounters this "Bipole" E-field antenna (as described in the above pdf document). This will be as opposed to the singular (non-differential) 'magnetic' induction of current in a standard 1/2 wavelength dipole antenna.

_Jim

Jim - in respect of your 'bipolar' antenna article. Can't read Croatian or whatever Eastern European lingo that article is written in. As you know, it's a requirement to present material here in English. So can you translate it accordingly? In the mean time I'll just make some preliminary remarks on a 'best guess' basis.

The pics and illustration Fig. 3 initially suggest an inductively loaded short electric dipole, but your field pattern of Fig. 4 is as you say very different to that of an electric dipole radiator. Seems to me what you actually have there is an inductively loaded linear electric quadrupole radiator - and the measured pattern is not the far-field radiation pattern but that of the near field. Otherwise you seem to be claiming 'new physics' - a radical departure from Maxwell's equations at work. Is that the case?

Further, how do you figure standard electric dipole works by way of 'magnetic' induction? So-called magnetic induction is connected with loop antennas - not linear electric dipoles!

[_Jim]

I would like to enter into the record an (almost) exclusively E-field antenna (in the near or reactive field area) of size 2 to 5% wavelength as contrasted with a small (< 1/5WL) loop (magnetic field dominant in the near or reactive field) or even the traditional 1/2 wave 'dipole' antenna.

http://trputec.com/s52st/bipol/9a4zz_bipol_antena.pdf

Note the on the second sheet (page 19) in FIgure 4 the depiction of the radiation (or reception) pattern of this antenna; I can confirm in my own experiments the same 'response' pattern.

Note well, the antenna response or 'pattern' is directly _opposite_ that of a traditional 1/2 wave dipole antenna. That is, maximum response (or radiated energy) occurs _end-on_ rather than _broadside_ as one has with the usual, traditional 1/2 wavelength dipole.

I am asserting that the antenna described in the above pdf document works on the principle of differential electric field 'induction' as an impinging EM wave encounters this "Bipole" E-field antenna (as described in the above pdf document). This will be as opposed to the singular (non-differential) 'magnetic' induction of current in a standard 1/2 wavelength dipole antenna.

_Jim

Jim - in respect of your 'bipolar' antenna article. Can't read Croatian or whatever Eastern European lingo that article is written in. As you know, it's a requirement to present material here in English. So can you translate it accordingly? In the mean time I'll just make some preliminary remarks on a 'best guess' basis.

The pics and illustration Fig. 3 initially suggest an inductively loaded short electric dipole, but your field pattern of Fig. 4 is as you say very different to that of an electric dipole radiator. Seems to me what you actually have there is an inductively loaded linear electric quadrupole radiator - and the measured pattern is not the far-field radiation pattern but that of the near field. Otherwise you seem to be claiming 'new physics' - a radical departure from Maxwell's equations at work. Is that the case?

Further, how do you figure standard electric dipole works by way of 'magnetic' induction? So-called magnetic induction is connected with loop antennas - not linear electric dipoles!

Unfortunately, you, too, seem to have fallen for what is pasted into textbooks as 'the truth'.

Suggest take a look at the Kinstar 'vertical' antenna and then come back to me and tell me the same line as above.

I was once like you, thinking only in terms of 1/4 wave antennas, and the two fields were important for radiation; I
am far less convinced these days.

Respectfully but sternly,

_Jim

PS Added during edit:

Test report for Kinstar, note the efficiency compared to 1/4 WL vertical reference antenna, page 7

http://www.kintronic.com/resources/tech ... ers/15.pdf

Seeing the results of this test reset my 'thinking' how antennas work WRT size, meaning, 'size' per se
is not that important a factor. And as of late, I am also thinking the H field is coming into play and
more important for radiation than E field.

[_Jim]

I would like to enter into the record an (almost) exclusively E-field antenna (in the near or reactive field area) of size 2 to 5% wavelength as contrasted with a small (< 1/5WL) loop (magnetic field dominant in the near or reactive field) or even the traditional 1/2 wave 'dipole' antenna.

http://trputec.com/s52st/bipol/9a4zz_bipol_antena.pdf

Note the on the second sheet (page 19) in FIgure 4 the depiction of the radiation (or reception) pattern of this antenna; I can confirm in my own experiments the same 'response' pattern.

...
_Jim

Jim - in respect of your 'bipolar' antenna article. Can't read Croatian or whatever Eastern European lingo that article is written in. As you know, it's a requirement to present material here in English. So can you translate it accordingly? In the mean time I'll just make some preliminary remarks on a 'best guess' basis.
...

Unfortunately, that is not a paper I authored. I did, however, build and repeat his experiment,
and using cut and paste from the author's paper did translate (using Google translate) the
Croatian text to English to determine if I was interpreting his diagrams correctly.

_Jim

[_Jim]

Jim - in respect of your 'bipolar' antenna article. Can't read Croatian or whatever Eastern European lingo that article is written in. As you know, it's a requirement to present material here in English. So can you translate it accordingly? In the mean time I'll just make some preliminary remarks on a 'best guess' basis.

Addressed.

The pics and illustration Fig. 3 initially suggest an inductively loaded short electric dipole, but your field pattern of Fig. 4 is as you say very different to that of an electric dipole radiator. Seems to me what you actually have there is an inductively loaded linear electric quadrupole radiator - and the measured pattern is not the far-field radiation pattern but that of the near field. Otherwise you seem to be claiming 'new physics' - a radical departure from Maxwell's equations at work. Is that the case?

Yes. Looks like 'loaded dipole'. Does not have response pattern like 'loaded dipole'. Would like
to understand this phenom as explained within context of *present* EM theory as no authors
in text books address this specific case.

(Also note 'loaded dipole' normally has current carrying conductor in/at center and 'loads' off toward
each end.)

Observations are as stated. Observed antenna pattern is not in congruence with what 'standard'
loaded dipole theory indicates; that is why I am here. We have gone beyond what the 'textbooks'
show into uncharted waters.

I discovered this phenom independently of the Croatian, where he observed this in 2005 or 2006.
I built something very similar and observed it last year (2013). Completely unexpected results.
Expected 'standard' dipole response. Got response as indicated in Fig 4.

Further, how do you figure standard electric dipole works by way of 'magnetic' induction? So-called magnetic induction is connected with loop antennas - not linear electric dipoles!

Current 'loop' maxima in center of dipole. This is well known. EM field will induce a current in
same direction on both dipole legs, with feedpoint in the center, on pk of one RF cycle the polarity
of one leg is + while other is -.

I and E loops and nodes: http://electriciantraining.tpub.com/141 ... 82_173.htm

Each 'leg' may be shortened without appreciable loss in radiation performance
(efficiency) IF ending load is used, that is, if the antenna is kept resonant.
Resonance assures maximum current at 'loop' point in the center.

As 'hams' a number of us have also observed that certain long-wavelength antennas
simply 'work' better if the center (current loop) is hoisted above ground, versus just
the ends (voltage loop).

Example, center of antenna above ground 1/8 WL and ends of antenna above
ground by 1/32 WL results in satisfactory performance vs overall antenna height
above ground of 1/16 WL. Analysis of this gets rather sticky and I don't have
time to get into it right now.

Also note the loop antennas would seem to operate differentially on the applied
magnetic field, since the same field excites both 'sides' of a loop yielding opposite
and (most likely perhaps) equal currents. The difference in 'time' from the field
transiting from one side of the loop to the other creates the 'useful' current in
the loop which may be extracted (thinking of the receive case now.)


_Jim

[Q-reeus]

...Unfortunately, you, too, seem to have fallen for what is pasted into textbooks as 'the truth'. Suggest take a look at the Kinstar 'vertical' antenna and then come back to me and tell me the same line as above.
I was once like you, thinking only in terms of 1/4 wave antennas, and the two fields were important for radiation; Iam far less convinced these days.

Respectfully but sternly,
_Jim

PS Added during edit:

Test report for Kinstar, note the efficiency compared to 1/4 WL vertical reference antenna, page 7
http://www.kintronic.com/resources/tech ... ers/15.pdf
Seeing the results of this test reset my 'thinking' how antennas work WRT size, meaning, 'size' per se
is not that important a factor. And as of late, I am also thinking the H field is coming into play and
more important for radiation than E field.

Checked the pdf article on Kinstar antenna. To me it obviously functions as a sparse top-loaded short monopole. The four horizontal arms do not contribute to the far-field but act as capacitive 'top' loading in effect. The ground plane will be the more-or-less symmetrical 'bottom loading'. Being a resonant high-Q design it achieves it's performance via relatively large reactive currents and voltages, and will suffer from low bandwidth wrt the longer 1/4 wave monopole. Something I'm confident will apply to your own even more severely high-Q antenna. Evidently you are seeing something different there - but what exactly?

Unfortunately, that is not a paper I authored. I did, however, build and repeat his experiment, and using cut and paste from the author's paper did translate (using Google translate) the Croatian text to English to determine if I was interpreting his diagrams correctly.

Can you upload your translation as e.g. attached pdf? Or at least explain precisely what he is claiming in respect of design and performance.

Current 'loop' maxima in center of dipole. This is well known. EM field will induce a current in same direction on both dipole legs, with feedpoint in the center, on pk of one RF cycle the polarity of one leg is + while other is -.

I and E loops and nodes: http://electriciantraining.tpub.com/141 ... 82_173.htm

Each 'leg' may be shortened without appreciable loss in radiation performance (efficiency) IF ending load is used, that is, if the antenna is kept resonant.
Resonance assures maximum current at 'loop' point in the center.

OK there has been a terminology issue confusing things between us. Never struck the term 'loop' for SW voltage/current maxima before. The usual term is antinode (or just maximum). When I referred to loop antenna - I meant an actual physical loop: https://en.wikipedia.org/wiki/Loop_antenna

No point quibbling further over such minor issues. What matters is to determine just how your antenna is actually operating, and just how you have measured the response to get that unusually smooth (and conventionally bizarre) 'transposed' double lobe pattern. So please detail the orientation (polarization) of the other antenna used when taking measurements, which one acted as receiver and which as transmitter, and at what separation distance as expressed in units of wavelength. Also, have you done any close-up current probing to determine the actual SW voltage/current profile along your antenna?
Without carefully establishing such things, no way I'm about to embrace what I suspect is a plug here for 'longitudinal scalar waves' a la Tesla Tech.
Respectfully but sternly - Q-reeus

[_Jim]

Bzzzzzt! I don't even pretend to know what you mean by 'scalar' waves and a reference to Tesla.

Please stick to the subject and the objective results presented. The discussion might just end right here.

_Jim

[_Jim]

You are also addressing issues in your posts I did not raise such as Q and BW; these are important in
the use and implementation, but since we are unable to even 'walk' yet in regards to understanding
the phenom presented, I think you are trying to 'run' too early ...

I have also not addressed testing in real world conditions using the WSPR network and performing
comparative testing against a wire dipole; transmissions were performed simultaneously to avoid
fades and other HF (SW to the public) band anomalies ... the purpose at the outset of all this was
to prove or disprove some of the 'wilder' antenna designs and/or theories roaming freely out there
on the internet ...

_Jim

[Q-reeus]

Bzzzzzt! I don't even pretend to know what you mean by 'scalar' waves and a reference to Tesla.
Please stick to the subject and the objective results presented. The discussion might just end right here.
_Jim

Getting a bit testy there. Settle down. A fact that should be obvious to you is this:
your claimed far-field pattern could only be true if so-called 'longitudinal waves' are involved. As opposed to the near universally accepted transverse waves of standard EM.
Extraordinary claims require extraordinary evidence, and until or unless you can convincingly supply that, the heat is on you my friend, not me.

You are also addressing issues in your posts I did not raise such as Q and BW; these are important in the use and implementation, but since we are unable to even 'walk' yet in regards to understanding the phenom presented, I think you are trying to 'run' too early ...

And throwing in your own far less common shorthand terms like WSPR without accompanying explanation doesn't help. Having accused me of 'not being able to walk yet', I take it you have some actual coherent theory to explain what you believe is happening? Like it's more than just empirical suck-it-and-see? Any equations to replace Maxwell's for instance?

I have also not addressed testing in real world conditions using the WSPR network and performing comparative testing against a wire dipole; transmissions were performed simultaneously to avoid fades and other HF (SW to the public) band anomalies ... the purpose at the outset of all this was to prove or disprove some of the 'wilder' antenna designs and/or theories roaming freely out there on the internet ...

From that I can tentatively take it than an electric dipole was the other antenna(s). Perhaps located far away with much and varied terrain in between. And that both functioned as dual transmitters/receivers. Which is straightaway bizarre since the wire dipole will only be capable of transmitting/receiving the 'usual' transverse Hertzian waves of standard EM. Yet your claimed bipol antenna pattern is consistent only with creation reception of 'longitudinal waves'!! You think not? Well please enlighten me with how it could logically be otherwise.

And I'm assuming here, given you claimed your pattern matches that of Fig. 4 in that Croatian article, that your antenna is therefore the 'bipol' design, and not a monopole! Clarification needed.

Also, how about explaining your take on just what the Kinstar antenna is supposed to be doing - having brought it up presumably as some kind of supporting evidence.