New understanding of electromagnetism could enable 'antennas on a chip'

April 8, 2015
Anechoic chamber. Credit: University of Cambridge

A team of researchers from the University of Cambridge have unravelled one of the mysteries of electromagnetism, which could enable the design of antennas small enough to be integrated into an electronic chip. These ultra-small antennas - the so-called 'last frontier' of semiconductor design - would be a massive leap forward for wireless communications.

In new results published in the journal Physical Review Letters, the researchers have proposed that are generated not only from the acceleration of , but also from a phenomenon known as symmetry breaking. In addition to the implications for , the discovery could help identify the points where theories of classical electromagnetism and overlap.

The phenomenon of radiation due to electron acceleration, first identified more than a century ago, has no counterpart in quantum mechanics, where electrons are assumed to jump from higher to lower energy states. These new observations of radiation resulting from broken symmetry of the electric field may provide some link between the two fields.

The purpose of any antenna, whether in a communications tower or a mobile phone, is to launch energy into free space in the form of electromagnetic or radio waves, and to collect energy from free space to feed into the device. One of the biggest problems in modern electronics, however, is that antennas are still quite big and incompatible with electronic circuits - which are ultra-small and getting smaller all the time.

"Antennas, or aerials, are one of the limiting factors when trying to make smaller and smaller systems, since below a certain size, the losses become too great," said Professor Gehan Amaratunga of Cambridge's Department of Engineering, who led the research. "An aerial's size is determined by the wavelength associated with the transmission frequency of the application, and in most cases it's a matter of finding a compromise between aerial size and the characteristics required for that application."

Another challenge with aerials is that certain physical variables associated with radiation of energy are not well understood. For example, there is still no well-defined mathematical model related to the operation of a practical aerial. Most of what we know about electromagnetic radiation comes from theories first proposed by James Clerk Maxwell in the 19th century, which state that electromagnetic radiation is generated by accelerating electrons.

New understanding of electromagnetism could enable 'antennas on a chip'
Dipole radiation. Credit: University of Cambridge

However, this theory becomes problematic when dealing with radio wave emission from a dielectric solid, a material which normally acts as an insulator, meaning that electrons are not free to move around. Despite this, dielectric resonators are already used as antennas in mobile phones, for example.

"In dielectric aerials, the medium has high permittivity, meaning that the velocity of the radio wave decreases as it enters the medium," said Dr Dhiraj Sinha, the paper's lead author. "What hasn't been known is how the dielectric medium results in emission of electromagnetic waves. This mystery has puzzled scientists and engineers for more than 60 years."

Working with researchers from the National Physical Laboratory and Cambridge-based dielectric antenna company Antenova Ltd, the Cambridge team used thin films of piezoelectric materials, a type of insulator which is deformed or vibrated when voltage is applied. They found that at a certain frequency, these materials become not only efficient resonators, but efficient radiators as well, meaning that they can be used as aerials.

The researchers determined that the reason for this phenomenon is due to symmetry breaking of the electric field associated with the electron acceleration. In physics, symmetry is an indication of a constant feature of a particular aspect in a given system. When electronic charges are not in motion, there is symmetry of the electric field.

Symmetry breaking can also apply in cases such as a pair of parallel wires in which electrons can be accelerated by applying an oscillating electric field. "In aerials, the symmetry of the electric field is broken 'explicitly' which leads to a pattern of electric field lines radiating out from a transmitter, such as a two wire system in which the parallel geometry is 'broken'," said Sinha.

The researchers found that by subjecting the piezoelectric thin films to an asymmetric excitation, the symmetry of the system is similarly broken, resulting in a corresponding symmetry breaking of the electric field, and the generation of electromagnetic radiation.

Microantenna. Credit: University of Cambridge

The emitted from dielectric materials is due to accelerating electrons on the metallic electrodes attached to them, as Maxwell predicted, coupled with explicit of the .

"If you want to use these materials to transmit energy, you have to break the symmetry as well as have accelerating electrons - this is the missing piece of the puzzle of electromagnetic theory," said Amaratunga. "I'm not suggesting we've come up with some grand unified theory, but these results will aid understanding of how electromagnetism and quantum mechanics cross over and join up. It opens up a whole set of possibilities to explore."

The future applications for this discovery are important, not just for the mobile technology we use every day, but will also aid in the development and implementation of the Internet of Things: ubiquitous computing where almost everything in our homes and offices, from toasters to thermostats, is connected to the internet. For these applications, billions of devices are required, and the ability to fit an ultra-small aerial on an electronic chip would be a massive leap forward.

Piezoelectric materials can be made in thin film forms using materials such as lithium niobate, gallium nitride and gallium arsenide. Gallium arsenide-based amplifiers and filters are already available on the market and this new discovery opens up new ways of integrating antennas on a chip along with other components.

"It's actually a very simple thing, when you boil it down," said Sinha. "We've achieved a real application breakthrough, having gained an understanding of how these devices work."

Explore further: A new topological insulator breaks symmetry, and that's a good thing

More information: Electromagnetic Radiation Under Explicit Symmetry Breaking, Physical Review Letters, 2015. dx.doi.org/10.1103/PhysRevLett.114.147701

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63 comments

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Steve_Cooper
1 / 5 (10) Apr 08, 2015
Electromagnetism is a result of an imbalance in the strong force plus weak force and gravity occurs when they the strong force and weak force are in balance.
Whydening Gyre
5 / 5 (7) Apr 08, 2015
I dunno what you mean by that, exactly, Steve... But this article is smokin'....:-)
TimLong2001
1.6 / 5 (7) Apr 08, 2015
The dipole structure of the photon establishes a specific wavelength, and antennae of the proper length pick off these components and transport these charges through the circuit.
Dethe
3 / 5 (6) Apr 08, 2015
The article talks about all of it like about breakthrough - but it's not clear, what is actually new in this research. If the dielectric antennae are used in mobile phones, then the principle cannot be new. The radiation released during acceleration of electron is routinely called a synchrotron radiation - but this term was nowhere used in the article. The generation of EM wave during vibrations of piezoelectric material is also known and utilized for example in frequency doubling (2nd harmonic generation) in every green laser pointer. My feeling therefore is, that the authors of article intentionally obfuscated the physical principle in an effort to make the research more breaking than it really is.
ab3a
4.5 / 5 (4) Apr 08, 2015
Warning: Antenna products and research are subject to more snake-oil salesmanship than most other fields. It is very math intensive and frankly, it gets very complicated. Wear boots before daring to tread in this BS.

If one is willing to put up with losses or very narrow bandwidth, it is possible to shrink an antenna to a very small size. Unfortunately, this also means that we discuss radiation efficiency compared to an isotropic radiator instead of actual antenna gain.

What the article seems to describe is that it might be possible to build an antenna smaller if it were surrounded by a dielectric material instead of air or vacuum. At that point I think the dielectric helps to resonate in concert with the radiator. But this still incurs losses in the dielectric. Furthermore, low loss high permittivity materials aren't cheap. Look up the price of Epsilam 10.

At the very least, it seems ignorant, and it may be worse than that.

verkle
Apr 08, 2015
This comment has been removed by a moderator.
verkle
Apr 08, 2015
This comment has been removed by a moderator.
Dethe
2.7 / 5 (7) Apr 08, 2015
Dielectric resonator antennae were first proposed by Long, et al., in 1973. Metal parts of normal antena which become lossy at high frequencies due to skineffect, thus dissipating energy. So that the dielectric antennas not only can be easily miniaturized, they can also have lower losses and be more efficient than metal antennas at high microwave and millimeter wave frequencies.
The photo of the microantenna shows a strong bend of 90 deg on the signal line. This is plain bad design
This is very good point.
Dethe
2.3 / 5 (6) Apr 08, 2015
Demonstration of dielectric resonator antenna principle. I met with this principle first during funny demonstration of trick, how to increase range of your central lock key.
Mike_Massen
2.7 / 5 (9) Apr 09, 2015
verkle claimed
This is plain bad design
Wrong.There r times when u must use right angles to exploit certain subtle radio frequency (RF) effects Eg Fractal Antennas & phased array coupling, its a recognised technique in some high end RF impedance matching lines for ultra high frequency (UHF) & higher communications & sensing...

verkle (sigh)
Analog signal lines need to follow a curved path for best transmission
It Depends; power, current, frequency, Q, EMC, space etc

verkle asked
Not sure if the best engineers are really working on this..
Thats correct you are NOT sure & shouldnt bark, you lack training & miss lab experiments as key to understand anything practical.

Eg Not seen Fractal based phased array antennas delivering high power at Giga-Hertx plus for seismology & remote sensing ?

verkle's pattern is to blindly follow books regardless of intelligence & devoid of education, where have we seen that ?

Statements aren't education in thinking !
verkle
Apr 09, 2015
This comment has been removed by a moderator.
grondilu
1 / 5 (1) Apr 09, 2015
to be removed please
Mike_Massen
2.6 / 5 (10) Apr 09, 2015
verkle claimed
Mike--you are really a show-off
No,
YOU claimed "..a bad design" showing immense ignorance of high-end RF [fractal] design.

verkle again with faith
And I believe you have no idea what you are talking about
Belief ?
As electronic engineer (1982) I've delved into high end high freq designs, u OBVIOUSLY have NOT.

verkle proves he didn't understand
90 degree bends will increase EMI (not EMC) no matter what the power, current, freq.
Wrong. NB: I stated 'exploit' !

There r occasions 90 deg tracks, in conjunction with approaches to minimising *externally* radiated Electromagnetic Interference (EMI) in modules for purpose of Electromagnetic Compliance (EMC), are used *internally* to attenuate certain harmonics.

If u were not ignorant u might think, arms of the bend have different resonant lengths for a reason !

verkle conceded
I lack training?
Obviously in RF, your ideas re PCB layouts r superficial ignoring internal RF effects !

cont
Mike_Massen
2.6 / 5 (10) Apr 09, 2015
verkle claimed
You are funny, because I am sure I have designed many more PCB's that you have
Really doubt it !

I've been designing PCB layouts since 1976 even with red/blue tape likely before u were even born !

verkle, u obviously barked trying to show off, arising from your narrow PCB experience noted in a book, without any ENGINEERING training in subtle & sophisticated RF effects exploitable *internally* in products BEFORE issues of EMI are required to be managed in terms of approvals re EMC *externally*.

As I said verkle, u only have belief with lazy unthinking faith trounced so very often by; training, knowledge, experience, intelligence & considered investigations into details from of attachment.

verkle asked
Best if you would just shut your mouth a bit more
No. I always challenge those who proclaim arbitrary ill considered beliefs spreading ignorant narrow views not commensurate with intelligence addressing situations outside their direct experience !
Dethe
2.6 / 5 (7) Apr 09, 2015
@Mike_Massen Sorry, but with full respect to your whole life experience with design of RF boards, werkle is fully right, as the impedance of right-angled path is mentioned in all design instructions, for example here. It has absolutely no meaning to dispute this issue with him. When transmission lines are required to bend (change direction) due to routing constraints, then a bend radius that is at least 3 times the center conductor width should be used. In other words:

Bend Radius ≥ 3 × (Line Width).

This will minimize any charactericstic impedance changes moving through the bend. The right angle must be compensated to reduce the impedance discontinuity caused by the local increase in effective line width going through the bend. A standard compensation method is the angled miter.
DarkLordKelvin
3.9 / 5 (7) Apr 09, 2015
The radiation released during acceleration of electron is routinely called a synchrotron radiation - but this term was nowhere used in the article.
That's because synchrotron radiation is something completely different .. did you READ the wikipedia link carefully before posting it. For one thing, synchrotron radiation is produced by FREE electrons traveling at relativistic speeds .. electrons in materials (e.g. antennas) do not have sufficiently long path lengths, especially at relativistic speeds, to emit synchrotron radiation.
The generation of EM wave during vibrations of piezoelectric material is also known and utilized for example in frequency doubling (2nd harmonic generation) in every green laser pointer.
Frequency doubling is not the same thing, because it relies on input EM power. Also, while optical materials used for frequency doubling are also piezoelectric (they lack inversion symmetry), I'm not sure the mechanisms are connected.
Dethe
1 / 5 (2) Apr 09, 2015
synchrotron radiation is produced by FREE electrons traveling at relativistic speeds
IMO you're confusing synchrotron and Cherenkov radiation. The synchrotron radiation is produced with ALL charged particles during change of speed, their initial speed or length of path plays no role in it - only deceleration/acceleration. Even the X-rays generated with braking of electrons in metal is synchrotron radiation and photons generated in LED during electron transitions (jumps) can be understood in the same way. Please refrain the premature RTFM remarks, or they could be applied just to you...;-)
Frequency doubling is not the same thing, because it relies on input EM power
The dielectric antennae also rely on input EM power, so I don't see any problem here....
Mike_Massen
3.9 / 5 (7) Apr 09, 2015
Dethe responded
.. Sorry, but with full respect to your whole life experience with design of RF boards
Understandable in verkle's limited experience it's quite correct but, he & maybe u r not recalling I said 'exploit' - where sharp bends offers means for a subtle benefit.

There are times when right angle is useful Eg. In conjunction with other materials such as ferrites (eg. not visible selectively integrated into PCB) & much higher frequencies than verkle has experienced where local *internal* mis-matched impedances offer absorption means, regionally & of subtle harmonics, not generally achieved conventionally, eg fractal segments to antennas

True for most conventional RF design u r correct etc at characteristic angles of incidence but, for verkle to claim "bad design" is narrow & incomplete, no view of other side's possible filter network eg swamp harmonic differential between the respective "tuned lengths" leading to/from the bend etc...

Thanks for link btw
Dethe
1 / 5 (2) Apr 09, 2015
regionally & of subtle harmonics, not generally achieved conventionally
These "harmonics" can be generated easily with every subtle impedance mismatch and engineers avoid them whenever possible. I don't see any benefit of the right angle shape in the above antenna.
Mike_Massen
3.7 / 5 (6) Apr 09, 2015
Dethe replied
These "harmonics" can be generated easily with every subtle impedance mismatch and engineers avoid them whenever possible
Indeed quite correct but, if you have a means to selectively absorb a subset of the generated harmonics eg by existing circuitry within the same enclosure and for a particular purpose then benefit can be gleaned, its subtle and beyond the scope of the audience on this forum. There is another reason for wanting local *internal* harmonics, also beyond scope of this forum ;-)

Dethe observed
I don't see any benefit of the right angle shape in the above antenna
I don't see that RA as an antenna, isnt it a "network" to match in a particular way the RF output of the device on the right with the connector on the left bottom edge of the board - ostensibly leading to a antenna which has its gain 'managed" via that network & SWR ?

ie.
Consider why the line isnt straight, ie a specific bend & length relation for particular purposes :-)
shavera
4.1 / 5 (9) Apr 09, 2015
I don't think those two lines, nor the right angle in them, are the 'antennae' relevant to the discussion here. The chip on the right is the antenna.

The point being that it doesn't behave like a classical EM antenna at all and instead relies on broken field symmetry within the dielectric material to generate radiation. That's a very novel idea, and doesn't necessarily require the traditional constraints of electrical engineering.

The associated wiring may induce some interference effects or noise, whatever. That's missing the forest for the trees.
shavera
4 / 5 (4) Apr 09, 2015
Also, I can't find the actual article in PRL or Arxiv. Just that it was accepted on 10 March 2015 by PRL, and the abstract thus associated.
Mordechai Mineakoitzen
4.2 / 5 (5) Apr 09, 2015
To the topic of 90 degree bends, both the good and the bad are addressed here: http://www.sigcon...bend.htm

Advanced PCB makers like myself, those tired of solvents and costly copper, know that the best route around the supposed ninety degree angle issue is to avoid PCB traces altogether and use quantum tunneling. It's been quite hard however to find ants that small who still take proper direction.
Mike_Massen
3 / 5 (4) Apr 09, 2015
@shavera
Good points, the whole issue is new & I recall Fractal antennas started to appear re EMC issues, all sorts of oddities which could be exploited which went counter to so called traditional views & although not common the so called Right Angle bend has a particular use in the very high-end RF remote sensing stakes which most people oon phys.org never get to see let alone appreciate.

@Mordechai Mineakoitzen
Nice link re strip line

I should point out, the paradigm I painted for verkle & he often says things from old bible based like tradition accepted whats written just has a very different aspect in conjunction with circuitry WHEN designed for a specific purpose to address just why one would want a particular essentially "non-smooth" transfer of power at a frequency or a range of frequencies not coupled directly with a harmonic relationship, being under confidentiality can be a pain but, suffice it to say these areas are advanced & worthy of consideration.
Moebius
5 / 5 (2) Apr 09, 2015
This article highlights one of my main criticisms of science today, "This mystery has puzzled scientists and engineers for more than 60 years." We should be spending 100 times more money researching anomalies like this. They may be the easiest places to find new physics.

Correct me if I'm wrong but I think the most important thing said in this article is this, "I'm not suggesting we've come up with some grand unified theory, but these results will aid understanding of how electromagnetism and quantum mechanics cross over and join up. It opens up a whole set of possibilities to explore."

Dethe
3.7 / 5 (3) Apr 09, 2015
Consider why the line isnt straight, ie a specific bend & length relation for particular purposes
You can tell me instead. From mine and werkle's perspective it's a "design flaw", which would lead into unwanted reflection and scattering of signal. Whereas from your perspective it's a "well & specially designed" feature...;-) So you should show us the alleged purpose of this "feature". Apparently you did design your circuits in this way whole your life without even realizing, why their output gets so noisy..;-)
Dethe
3 / 5 (2) Apr 09, 2015
This article highlights one of my main criticisms of science today .... understanding of how electromagnetism and quantum mechanics cross over and join up
I don't think, that the Maxwell's description of the inhomogeneous dielectric leads into quantum mechanics automatically. The behavior of dielectric antennae can be predicted and designed fully with classical Maxwell's theory - this subject is forty years old new and there is no mystery here. To prove that the quantum mechanics gets involved the pointing to symmetry breaking is not enough. I've rather problem with modern scientific journalism, which tends to pretend, that every particular insight gets more important, than it really is.
Dethe
1 / 5 (1) Apr 09, 2015
The basic idea of quantum mechanics is in dynamic response of environment to energy density of environment. This is the main difference in which the Hamiltonian and Maxwell mechanics differs from quantum mechanics. If we simplify the difference, than the Maxwell mechanics describes the spreading of light wave across non-homogeneous dielectrics like the dielectric antenna - something like the spreading of light through foam of variable density. But only at the moment, when the density of foam directly and dynamically responds to actual energy density of the passing light wave in a given place and moment (i.e. in similar way, like the beer foam during shaking), then you'll get the quantum mechanic behavior. The simple scattering of EM wave and its frequency doubling is not enough here. Which also means, that the quantum mechanics can be never fully emulated with material of some fixed structure or geometry - no matter how complex this geometry is.
Mike_Massen
2.3 / 5 (3) Apr 09, 2015
Dethe tried to goad
You can tell me instead
There is obviously a reason for making it a tad more involved by having a right angle turn, one aspect of which is you have the sum of two resonant lengths and between them is a point of discontinuity.

Dethe claimed
From mine and verkle's perspective it's a "design flaw", which would lead into unwanted reflection and scattering of signal
Not necessarily Please read pertinent post by shavera, I quote"..doesn't behave like a classical EM antenna".

Dethe claimed
Whereas from your perspective it's a "well & specially designed" feature...;-)
I never said that, I stated clearly there can be reasons for a RA in high end RF. Hasn't it occurred to you a straight line is easier AND far more efficient, so obviously its specifically sidestepped for a reason.

Dethe trying to goad again
So you should show us the alleged purpose of this "feature"
Already did, to exploit a benefit, please read my post.

cont
Dethe
3 / 5 (2) Apr 09, 2015
There is obviously a reason for making it a tad more involved by having a right angle turn, one aspect of which is you have the sum of two resonant lengths and between them is a point of discontinuity
Yes, but why? Why someone would want to test the dielectric antenna with circuit composed of two impedances in serii instead of pure harmonic signal? BTW How long do you want to pretend, that you were aware of the design flaw, which werkle pointed out above just for the sake of saving your face before readers here? I can assure you, I can be quite persistent in this game...;-)
Mike_Massen
2.3 / 5 (3) Apr 09, 2015
@Dethe

attempting sarcasm with
Apparently you did design your circuits in this way whole your life without even realizing, why their output gets so noisy..;-)
No.
Unfortunately you didn't read my post, there are reasons for specifically doing it that way for a particular purpose, obviously that purpose is in conjunction with an aim for that arena of research. its not automatically anything I do (unthinkingly) as you might imply.

Feeble attempts to goad me into disclosure don't add to your credibility or integrity. Please try to understand, RF design at high level of; power, freq spread, rise time, harmonics etc is much like a black art. I have seen designs following standard practices fail whereas others with less than satisfactory design rule criteria work remarkably well, it all depends on sophisticated details thought though with benefit of excellent instrumentation.

I have said enough on this topic & I hope you appreciate verkle's faith was unhelpful.
Mike_Massen
3 / 5 (2) Apr 09, 2015
Dethe asked
Yes, but why?
A better question than verkle lurching off with naive attack upon the (PCB) layout.

Did you not read Shavera's post or insist on ignoring his points, please re-read.

Dethe imagined
Why someone would want to test the dielectric antenna with circuit composed of two impedances in serii instead of pure harmonic signal?
Insisting on simplifying to your level of traditional experience cannot help you understand a range of combinatorial complexities which may be explored in this design "as a research project".

Dethe claimed
BTW How long do you want to pretend, that you were aware of the design flaw, which verkle pointed out above just for the sake of saving your face before readers here?
Where ? Never claimed to be aware of ANY design flaw, its because I know there are reasons, in a research project, for specifically NOT proceeding along traditional lines.

Dethe
I can be quite persistent in this game.
No game. Education.
Dethe
3 / 5 (2) Apr 09, 2015
there are reasons for specifically doing it that way for a particular purpose
LOL, which ones? Why someone mentally healthy would want to complicate the measuring of nonlinearity of antenna with adding the irreproducible noise at the input with apparent design flaw?
combinatorial complexities
The Occam's razor says, it's design flaw without any abstract reasoning needed.;-) The handwaving of yours and spreading of fog without clear answer indicates, you have no rational answer prepared.
Mike_Massen
3 / 5 (2) Apr 09, 2015
Dethe asked
LOL, which ones?
Good, you can email & ask them ?

Dethe imagined
Why someone mentally healthy would want to complicate the measuring of nonlinearity of antenna with adding the irreproducible noise at the input with apparent design flaw?
There you go, bringing this down to a level you are only traditionally acquainted with, that doesn't help your understanding. Suggest you apprise yourself of the IEEE papers relevant, free printed versions to peruse in the reference sections at your local university if they are paywalled for internet access. These papers are a wealth of information & ideas helpful to you.

I'd recommend you examine your assumptions especially the conjunctive terms implying various issues you consider in your question.

Dethe claimed
The Occam's razor says, it's design flaw without any abstract reasoning needed.;-)
Simple. Choosing to replace a straight line is NOT abstract, please take advice read the IEEE...

continued
Mike_Massen
3 / 5 (4) Apr 09, 2015
continued

@dethe

claimed
The handwaving of yours and spreading of fog without clear answer indicates, you have no rational answer prepared.
Sure. Not prepared to go into details, best you discover yourself, by taking the requisite advice & actually getting an Education reading the IEEE papers as I urged.

Nothing prepared, I don't see how I could or should have. Article is relatively new, the PCB layout is not outside experience. It is outside verkle, he criticises what he has no experience of & goes to the trouble to find a link with no caveats or qualifications re issues of sophisticated RF design in a research environment as is the basis of the article & you get excited.

Unfortunately, you're showing your level of maturity labeling communication a game. Its an issue of education, I went to the trouble to point out to verkle this is beyond his experience of PCB layout as other factors are obviously involved.

Please see IEEE papers. I'm not your teacher.
JamesKeene
not rated yet Apr 09, 2015
The "broken symmetry" idea presented by the article authors may correspond to the asymmetrical motion of individual 1-state bits carrying charge along one of three spatial dimensions, described in the upgrade of quantum mechanical ideas known as binary mechanics. E.g., the circular motion of negative charge at electron loci is so rapid compared to macroscopic time intervals, making the asymmetry undetectable. Perhaps the work of the authors of the PRL report has detected the underlying asymmetry and thereby provided unexpected support for the binary mechanical update.
abecedarian
5 / 5 (3) Apr 09, 2015
http://www.ultrac...0deg.pdf

"Traces 3 (90o corners) and 6 (45o corners) both radiated slightly higher than did Trace 2 (no corners). Trace 6 actually radiated slightly higher than did Trace 3, contrary to any expectation."
"The TDR data do not show any measurable reflections from either 45o or 90o corners in microstrip traces. In theory, there is a change in Zo caused by a corner, but the effect is not sufficient to be resolvable with a 17 ps rise-time pulse."
verkle
Apr 09, 2015
This comment has been removed by a moderator.
abecedarian
5 / 5 (2) Apr 09, 2015
Explain inverted F antennas and why they are constructed with 90 degree transitions please...
... and why cell site panel antennas have 90's where the connector bulkhead connects to the radiator.
DarkLordKelvin
3.7 / 5 (6) Apr 09, 2015
synchrotron radiation is produced by FREE electrons traveling at relativistic speeds
IMO you're confusing synchrotron and Cherenkov radiation.
Well .. your opinion isn't really relevant, since I made correct statements (according to physics) about synchrotron radiation; Cherenkov radiation cannot be emitted in vacuum.
The synchrotron radiation is produced with ALL charged particles during change of speed, their initial speed or length of path plays no role in it - only deceleration/acceleration.
Larmor derived EM radiation from charges under acceleration in 1897; synchrotron radiation wasn't discovered for another half-century, from electrons orbiting inside a particular accelerator known as (wait for it) A SYNCHROTRON!
Please refrain the premature RTFM remarks
Please RTFM then, so that you avoid misrepresenting important definitions from the physics content of your own links, and using them to justify spurious criticisms of legitimate scientific work.
abecedarian
5 / 5 (3) Apr 09, 2015
http://www.bigcar...-USA.pdf

"For almost all test configurations, the 45 degree corner radiated more than the 90 degree corner by 2-5 dB in the frequency range of 400-600 MHz."

"Time domain (signal integrity concerns): ...no measurable reflections from 90 degree, 45 degree or round corners...."

"Frequency domain: Radiated emissions exist, however, measurements up to 1 GHz does not show an increase for 90 or 45 degree corners that is of any significant amount greater than the level of uncertainty of the measurement equipment... discontinuities within component packages, connectors, layer jumpering vias and common-mode currents within the transmission line will radiate at levels that far exceed any measurable effects from any corner configuration. Corners do not appear as radiated emissions until the upper MHz range, and even then, the magnitude of the signal is minimal. It is difficult, if not impossible to measure radiated emissions from any trace corner."
Mike_Massen
3 / 5 (4) Apr 10, 2015
verkle uttered
In digital signals it is OK to have 90 deg bends, but not for analog/RF signal paths
In your narrow experience that may be true. Times when 'digital' signals should NOT be routed with 90 RA in depends as you SHOULD know on the combination of freq, power & one other important property. In any case u don't make the distinction re a digital RF & a benefit being gained by specifically arranging two segments of a particular resonant freq being joined by a RA & in relation to the circuitry on the other side. Read Shavera's & ALL my other posts.

verkle claimed
Mike---just for your information, I have 3 college degrees, one being in EE with an emphasis on semiconductor design
Irrelevant to experience but, OK Good prove it ?

Which institute & when did u start each course ?

Challenging qualifications is an appeal to authority for your lack of experience ?

verkle claimed
I know what I am talking about
Only your experience, read ALL my posts !
Mike_Massen
4 / 5 (4) Apr 10, 2015
abecedarian offfered
Explain inverted F antennas and why they are constructed with 90 degree transitions please...
... and why cell site panel antennas have 90's where the connector bulkhead connects to the radiator
Good point, thanks for the links.

@verkle
Your claimed EE degree (when?) u would have been educated in physics & thus have the training (easily) to extend your understanding beyond any qualifications which claimed ?

Appeal to authority same as your claim 'a god did it' by virtue of Moses' old testament with its flawed logic consistent with disjointed dreams NOT intellect we SHOULD expect of a deity who educates fully.

verkle u start out with predisposition to parroting without thinking things through just WHY there could be a benefit in right angle bends depending upon; Frequency, harmonics, Power, Impedance, Q, SWR, etc & ALL permutations therein !

abecedarian had the interest to find links appropriate, please read & thank him verkle AND dethe ?
abecedarian
5 / 5 (3) Apr 10, 2015
@Mike_Massen - You're very welcome.

I work in an RF industry - designing and building cell sites. Us people out here actually DOING the work fought long and hard proving the desk-bound EE's their theories were wrong.

I was always told "no 90s" for connectors and such by AT&T EE's. When I pointed out Ericsson 880 series equipment had 90s from the RF output stages to their auto-tune combiners, their eyes glazed over... but they insisted no 90s on the coax after the combiners.

When GSM came about, they again insisted on no 90s, but those pesky Ericsson people insisted on having a door on the BTS requiring 90s so as to allow that door to shut.

Along comes E911 equipment and now we have LMR-214 cable to connect to a device with SMA type connectors and... because they were rack mounted cables flying out into space wasn't an option and required 90s we had to build in-situ.

Long story short: lot's of 90's in RF, both coaxial and on boards. No problems.
abecedarian
5 / 5 (3) Apr 10, 2015
TDR and FDR test equipment, alongside PIM, the latest / greatest guarantor of quality all reveal that 90s do not substantially nor significantly affect the RF signal so as indicate 90s cannot be used.

The simple fact the links I provided indicate 45s produce more EMI and such than 90s completely nullifies any argument against 90s.
Mike_Massen
3.7 / 5 (3) Apr 10, 2015
abecedarian offered & reminded me of
..their eyes glazed over... but they insisted..
:-)

Seen this reaction a few times, once in particular when an EMC approvals tech (graduated as theoretical physicist & moonlighting) was quite ho hum when he saw a special thin ceramic PCB with frequent use of many RA bends on one side of a board at ~2GHz b/w whilst other side some ~4 to 8 GHz circuitry was up to 'something' ;-)

Suffice to say, tech was casual & ho hum as he understood there was an oddball reason because the setup worked well & had a (almost scary alien-tech Extremely) sharp roll-off rate way beyond anything ever seen.

Supervising EMC test engineer, even with ~20yrs experience, brushed it off as some "obviously" rushed prototype flawed design & "..what do theoretical physicists know anyway", blah blah ignored it !

Turned out was an active filter injecting harmonics of particular & dynamic power/phase/freq relationships to the RA bend impedance at the region.
swordsman
not rated yet Apr 10, 2015
This article is flaptrap and gobblety-gook. Saying you understand something does not necessarily mean that you do. All electromagnetic radiation is "dielectric", involving Coulomb forces that vary with time.

See "A Different Picture of Radiation", IEEE Antennas and Propagation Society International Symposium 2003, page III-478 in which the dynamic Coulomb field waves are defined.
hudres
3 / 5 (2) Apr 11, 2015
Most of the comments above are on point. The concept of micro-scale antennae was realized both in practice and patent at least 20 years ago. I am not going to bother commenting on specific technical points. What I would like to raise as a discussion topic is why does this website constantly post every news release it receives without benefit of fact checking? It would not take that long, but would significantly add to the credibility of this site. Phys.org has the ability to be a great website but its constant oversight of other peoples intellectual property (mine included: I have commented on this many times in the past) does a great disservice to smart and dedicated people merely for the sake of the glory of "I Posted It First" More often than not, you end up with mud on your face and reduce the credibility of your website. I defy the management of this website to address this matter directly and publicly. Does anyone else care about this and support this idea?
Da Schneib
3.7 / 5 (3) Apr 12, 2015
The point of this discovery is that it has not been described quantum mechanically how moving electrons in a solid, where the mean free path length is comparatively short and there is no strong magnetic field, radiate electromagnetic energy. It's not synchrotron (more generally cyclotron) radiation, which is emitted due to acceleration of charged particles by a magnetic field, and it's not Cerenkov radiation, which is emitted by any particle moving faster than the local phase velocity of light in a dielectric medium with a lower phase velocity of light than the speed of light in a vacuum, "c."

Maxwell's equations don't describe it, and quantum mechanics doesn't describe it. This discovery, if it's correct, will do so. And the key to it is that it's due to symmetry breaking.

This is not the invention of a new type of antenna. It's the discovery of precise mathematical descriptions of how antennae work.

cont'd
Da Schneib
3.7 / 5 (3) Apr 12, 2015
As a former ham radio operator, and an EE, I have always been aware that antenna engineering is purely practical, rather than theoretically well understood and well founded; that is, our knowledge is purely empirical. We do not understand how or why antennae work; we just understand how to make antennae that work, which we have discovered through experimentation. There is neither a QM nor a Maxwellian mathematical theoretical foundation for any of it, only practical experimental data, even for the simplest dipole antenna (which is merely two long wires, of equal length, each one-half the wavelength of the frequency of the signal to be transmitted or received). This is clear from the fact that transmission line theory requires two different sets of equations for frequencies whose wavelengths are comparable to the line length, and frequencies whose wavelengths are much shorter.

As a result, antenna design is much more an art than a science. This new mathematical treatment fixes that.
Da Schneib
3.7 / 5 (3) Apr 12, 2015
Oh, and of course, as the article mentions, it's also clear that dielectric antennae are not well understood theoretically. And this discovery, again if it's correct, vastly increases that understanding, and according to the article allows microminiaturization, rather than the current miniaturization, of these antenna designs.

Current designs are millimeters wide; far too large to be put on a chip. New designs at the micrometer (micron) scale appear, according to the article, to be practical using this new theoretical understanding, which is a decrease in scale of a thousandfold.

Consider two dipole antennae, one with the two wires leading from the feed going in opposite directions (broken symmetry), and one with the two wires parallel to one another (symmetrical). The second isn't a very good antenna; the first is. Now we see why.
Da Schneib
3.7 / 5 (3) Apr 12, 2015
The concept of micro-scale antennae was realized both in practice and patent at least 20 years ago.
Note however that it was not theoretically understood until now. And that's the point, which you appear to have completely missed.
Returners
5 / 5 (1) Apr 12, 2015
Seems to be useful in developing the ultimate telescope/array system for astronomy.
EWH
1 / 5 (1) Apr 12, 2015
"Symmetry breaking" is about as specific as saying " it involves math". They should look at what their Cambridge colleagues were doing many years ago, for instance in "Applications of Geometric Algebra in Electromagnetism, Quantum Theory and Gravity" by A. Lasenby, C. Doran and E. Arcaute, especially figure 2. of that paper "Scattering in two dimensions." ..."an exact, analytic expression for the fields at any point in space...the calculations fully incorporate all diffraction effects and polarisations, as well as correctly accounting for obliquity factors."
Da Schneib
3.7 / 5 (3) Apr 12, 2015
"Symmetry breaking" is about as specific as saying " it involves math".
Not really.

Maybe you missed the implications of the two dipole antenna configurations I discussed above. When they're parallel, they are symmetrical, leaving the field values around the antenna unchanged; and leaving field values unchanged is the definition of symmetry. In fact, two parallel wires is a transmission line, which is made to radiate minimally, thus transmitting power instead of radiating it. Radio engineers call this "ladder line," and it's very common in HF radio because it's cheap and effective. OTOH, if the two lines are sent off in opposite directions, then the two signals from the two wires cannot cancel, and the power is radiated by the wires rather than transmitted by them.

Your paper doesn't include anything about antennae. You'll need to find something that discusses physical symmetry of the antenna elements, and the effects of breaking it.
abecedarian
5 / 5 (2) Apr 13, 2015
Before I continue, I need to correct myself. Previously, I posted about LMR-214 cable when I meant LMR-240. The assertion remains the same though: coax to [typically] SMA/SMB termination with right angle interface into a 'tuning fork' like conductor: coax center conductor mates with the center conductor of the connector body. Representative image http://www.rfpart...2_1.jpg.

>continued
abecedarian
5 / 5 (2) Apr 13, 2015
>continued

This sort of reminds me of "The Little House on the Prairie" episode where Laura meets up with the new town banker at the local fishing hole. He proudly states he's read every book about fishing and the lure he's using is completely appropriate for the pond he's fishing in. Laura climbs out on a fallen branch, wads a dough-ball on the hook and drops it in, only to pull up a fish within moments. Another instance or two of this, she remarks that the fish in the pond haven't read his books so they don't know how they're supposed to act.

He is flummoxed and insists he's doing things correctly while she's proving him wrong most every step.

The rest is unrelated drama, so I'll leave that alone with this:
No matter what you know, there's always going to be someone who knows more than you. To insist you're right when it's possible you're not is a waste of everyone's time and energy.
abecedarian
5 / 5 (2) Apr 13, 2015
Damn, forgot the whole point....

@verkle @Dethe et al - If you can't use 90's in RF why does it seem everyone uses them?

Why does an inverted-F antenna work better with 90's than 45's would be a start.
abecedarian
5 / 5 (2) Apr 13, 2015
TI has a product: CC-ANTENNA-DK-RD with 13 antennae covering 169 / 315 / 433 / 868 / 915 / 2440 MHz... I think mostly ISM bands, with OPEN / SHORT / LOAD calibration points. You'll have to search for it since PO won't let me link it.

5 antennae use coils, and curved board traces.
5 antennae use 90s FOR the antennae.
3 use 45s to supply chip antennae.

As we've learned previously, TI doesn't just toss out recommendations for designs such as the validated op-amp circuits @verkle linked, nor the validated antennae designs I've pointed people at.
abecedarian
5 / 5 (2) Apr 13, 2015
Since @verkle chose to cite a TI "design reference" from 2008, predominately related to op-amp design in the analog domain as a "bible" for power and RF, it seemed only fitting I cite a TI RF design reference as "RF".

In the last 20 years building cell sites and doing RF engineering, admittedly without a degree in either, I can count on one hand the number of times the EE design worked better than my field-engineered, back-woods logic design.

When EE's stop considering RF as DC-offset voltages, you might get somewhere.
Da Schneib
5 / 5 (1) Apr 17, 2015
@abecedarian, I think a lot of EEs only learn computer logic. They leave out RF quite commonly, or the students forget it. It's kinda like switching power converter design; it's kinda complicated and mathematically requires calculus, so they go for the easy stuff and ignore the hard stuff. It's easy to do, since a lot of electronics is computer design, and there's a lot of money there, without having to do any scary integrals.

But if you wanna do communications, you either have to have the real world experience, or you have to the scary integrals. You sound like you have the real world experience.
DarkLordKelvin
3.7 / 5 (3) Apr 17, 2015
@abecedarian, I think a lot of EEs only learn computer logic. They leave out RF quite commonly, or the students forget it. It's kinda like switching power converter design; it's kinda complicated and mathematically requires calculus, so they go for the easy stuff and ignore the hard stuff.
I have been on the receiving end of this, when a major company put a switching power supply into an arbitrary waveform generator, and then made it voltage-selectable for 110 (US) and 220 (Europe). Of course they neglected to think about the fact that the frequencies are different as well (60 vs 50 Hz), and apparently they only tuned/tested their supplies for 60 Hz. The thing worked fine in the US, but when we took it on a visit to Europe, we had all kinds of crazy-intense interference in comm band freq's, so I wasted a bunch of time looking up nearby commercial radio stations and military installations until I realized what the issue was. Switching to DC battery power worked like a charm ;)
Da Schneib
5 / 5 (2) Apr 17, 2015
Switching to DC battery power worked like a charm ;)
Heh.

The worst thing is, if they knew the canonical method, they could have run the numbers. This is simple incompetence.

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