
New Theory Leads to Gigahertz Antenna on a Chip - jonbaer
http://spectrum.ieee.org/tech-talk/telecom/wireless/gigahertz-antenna-on-a-chip
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emcrazyone
I took antenna theory in college for a couple years and then worked in the
automotive field designing in-glass antenna systems for cars in the 1990s for
a few years.

It has been a few years but reading the article I couldn't help but recall
some of my college courses and how I was able to apply some of what I learned
in college to the state of the art at the time.

We use to have to drive cars by a local glass company to have the rear window
removed and taped back in until I got to the office. Once at the office I
would lay the glass on a metal frame and layout an antenna using gold
conducting tape. Put the windshield back into the car and blast it with
network spectrum analyzer.

Antenna's have both a theoretical wave length and an actual wave length as
measured through the medium you're radiating from.

We had loads of conduit in our work shop so one day I managed to grab a couple
pieces of conduit and made some rough back of the napkin calculations to
convert the theoretical wave length to an actual wave length for metal
conduit. My work was for AM and FM radio in the 88-108MHz.

One day a customer comes into the office who knew me well from many visits and
saw me hack sawing a piece of conduit with a wire hanging off the side. He
asked what I was doing and I told him I was calibrating an antenna.

We were a start up so we had to make due with stuff lying around.

I couldn't help but read the article and wonder how the dielectric mentioned
would effectively shorten the wavelength. Wave length in a medium can be
thought of the effort to push back and forth the electrons to radiate.

Another analogy is it's easier to wave your hand in air than it is in water;
water being akin to the dielectric. A dielectric with 60% efficiency seems
more material science than electrical engineering.

Interesting work. Curious what materials they use or perhaps going to higher
frequencies.

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TTPrograms
One basic point to keep in mind here is that in dielectrics the wavelength of
radiation can be many times shorter than in freespace - up to 20 or 30 in some
cases. So if you have some system that is too small to set up the resonances
you would need for an antenna you can put it in a dielectric with a high K
value and the resonances will all be shifted to higher frequencies.

It looks like there's an interesting bit of analysis in here, but that basic
concept is as as old as Maxwell. As for gigahertz antennas on a chip... well,
you all probably have one in your pocket :)

~~~
neutronicus
Yeah, looking at the PRL, it sounds like they're advertising a new theoretical
framework for _designing_ antennas, not, like, some new, henceforth-
undiscovered law of Electromagnetism.

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ramanan
After having read the PRL paper [1], I am not really sure why they left out
gain (and pattern) measurements for the antennas. In my experience, radiation
efficiency is only one part in determining the received signal strength. The
impedance match is also crucial in determining the effective gain.

The figures in their paper also seem to demonstrate strong resonant coupling
effects, which do not always translate to effective radiation.

[1]
[http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.114...](http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.114.147701)

~~~
upofadown
Since the antenna is quite small it would be bad at receiving signals for that
reason alone. Reception isn't really the important issue here though...

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Gravityloss
Incredible that things that, at least to me, seem rather close to the
fundaments, are still discovered today.

~~~
walterbell
See also memristors.

~~~
UnoriginalGuy
Looks like memristors are still coming, but now pushed back to 2018. They have
actually built them however so they aren't complete vaporware.

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phkahler
I'd like a TV receiver in my phone, along with FM radio.

~~~
cjensen
Both of those requests are already done. They're just not popular,
particularly in the US.

~~~
sp332
And they both need external antennas. The FM radios usually use the headphone
wires as an antenna, but the TVs I've seen have long retractable antennas.

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sp332
They mention that the new antennas are very thin, but how big are they?

Also, is it true that Maxwell's equations don't describe this phenomenon?

~~~
throwaway8198
Maxwell's equations do describe antennae. Well, to be more accurate, the most
current equations do.

(An American antenna expert updated one of the equations around 20 years ago
based on his experiments in antenna performance.)

~~~
neutronicus
> (An American antenna expert updated one of the equations around 20 years ago
> based on his experiments in antenna performance.)

What are you talking about?

~~~
ramanan
Perhaps what throwaway8198 is referring to are the practical consequences of
Maxwell's laws as formulated by an American team in the 1960s [1]. For a
thorough, more recent study, I highly recommend [2].

[1]
[https://en.wikipedia.org/wiki/Chu%E2%80%93Harrington_limit](https://en.wikipedia.org/wiki/Chu%E2%80%93Harrington_limit)

[2]
[http://web.eng.ucsd.edu/ece/courses/ECE222D/Spring2013/Lectu...](http://web.eng.ucsd.edu/ece/courses/ECE222D/Spring2013/Lectures/Small%20antenna%20validation.pdf)

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lightlyused
Nothing new here. This is nothing more than an OCF antenna with one side being
a lumped inductance.

