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Symmetry breaking could enable antennas on a chip


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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.

The researchers have proposed that electromagnetic waves are generated not only from the acceleration of electrons, but also from a phenomenon known as symmetry breaking. These new observations of radiation resulting from broken symmetry of the electric field may provide some link between the two fields.
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.
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.Piezoelectric materials can be made in thin film forms using materials such as lithium niobate, gallium nitride and gallium *. Gallium *-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.

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I could be highly thrilled at the breaking of new frontiers by these scientists but this bit worries the hell out of me and I wonder if we will end up with Big Brother in our homes:


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. - See more at: http://www.cam.ac.uk/research/news/new-understanding-of-electromagnetism-could-enable-antennas-on-a-chip#sthash.P9FfiFGG.dpuf


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Symmetry breaking is not my field, but antennas are, and, how to say...


That paper starts very badly. The part about transmission lines not radiating uses formulas established for DC currents in infinite wires - exactly what cannot work for antennas. Then this author "prooves" that two parallel wires can't radiate, despite such antennas have been working for a century.


Sorry, that research paper contains nonsense that would not be accepted from an electromagnetism student.


Then the paper swiftly switches to Noether's theorem, symmetry breaking and other things. I fear this parts makes as little sense as the one on electromagnetism, and even, that the reviewers let the paper through, not because they understood and approved the simple part, but because they got impressed by the complicated one and by the prestigious university.




About the radiation by dielectric polarization current, there isn't so much of a "mystery"...


Vacuum polarization is not a movement of accelerating real charges hence it doesn't radiate.

The added permittivity (relative epsilon minus one) is a charge movement and does radiate.

The maths behind it may be horribly obscure if starting from Maxwell's equations, and I never saw it done, but the concept is simple.




Their piezo antenna uses a mechanical resonance to let many electric charges move a lot, in an attempt to let a small antenna be efficient. That's the interesting and sensible part of the paper, if the uses accept a narrow bandwidth.




To my opinion, the paper's part about electromagnetism and symmetry should not have been written nor accepted for publication.

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I have spent my entire life , trying to get clear in my mind ,what quite goes on around an antenna . From the first wide eyed shock of learning that something happened around an aerial that 'allowed, or made ' the radio wave to speed out across the void to some distant land at a ' phenomenal speed ' and arrive intact , to be heard in that distant land . To this present day , and I must say , I do not feel , terribly advanced in my mental picture of what ,quite , is going on . A 'shed full ' of maths from two universities , has filled my head with a lot of three dimensional complex numbers, Div, Grad, and Curl , and maxwells equations . But still I can not picture what is going on.


I asked the relevant lecturing professor ,in each university , to describe pictorially ( so I who thinks in pictures , can ,could, understand . And the reply from each professor , different, but interesting , I think ....


The more recent one said " we all have to go through this , we all have to learn and repeat the maths , we had to do it so you do. You have to manipulate Maxwells equations , know the formulae, do the maths , all the complex variables in three dimensions , and all "


But "what is actually going on ? " I being then in my 50's and ' brazen enough ' to dare to ask. "

He said " Mike , let's go and have a cup of coffee , and I'll tell you how I see it. We don't teach this , because this is just the way I have reconciled it in my own mind . Nobody really knows, but this is how I see it ... "( this was all back at the turn of the century 2000 ' ish , things may have moved on a bit ) .


" Well it is all to do with frequency and the electro- Magnetic fields developed around the driving circuit and antenna .. This is what I believe is happening .. " remember this is his personal visualisation , not the university curriculum ( that stops with the maths ) .


Well..the AC signal created by the driving circuit at a certain frequency sine wave , sets off down the transmission line and arrives and is absorbed ( due to impedance matching ) into the antenna and it's surrounding. 'Electro magnetic field ' . This field spreads out around the antenna to a certain distance before the falling level of the sine wave starts to decrease and head for the zero point and negative . direction. During this process the collapsing magnetic field induces , back into the antenna. And life goes on with no transmission, just an oscillating near field . This works ,up to a certain low frequency ( as in below long waves ) . Above a critical frequency , the time of the half cycle , is too quick to self induce back into the antenna. So it somehow pinches off on itself , and heads off as a photon of energy into the .. Great beyond .. Like a bubble ...




Now it is true this was his personal visualisation by the professor , which helps me, but of course is not necessarily how it is! Sounds plausible though . This does make sense when , if , you have blown bubbles through a ring , a continuous stream of bubbles heads out . As each one pinches off ,the next follows, and on and on.

Below a certain wind, puff speed , the stretched film , returns taught to the ring ,and does not transmit out as a stream of bubbles. Above that critical puff speed , whoosh the steam of bubbles starts until you run out of puff or soap film supply. There is a machine now that will send out continuous streams of bubbles for parties or dances.



Edited by Mike Smith Cosmos
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