New Theory Leads to Gigahertz Antenna on a Chip

http://spectrum.ieee.org/tech-talk/telecom/wireless/gigahertz-antenna-on-a-chip

by jonbaer • 11 years ago

69 22 11 years ago

spectrum.ieee.org

Gravityloss• 11 years ago

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

walterbell• 11 years ago

See also memristors.

UnoriginalGuy• 11 years ago

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

phkahler2• 11 years ago

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

cjensen• 11 years ago

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

sp3322• 11 years ago

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.

fennecfoxen• 11 years ago

"The hidden FM radio in your pocket and why you can't use it" (110 points by anigbrowl 3 days ago | 100 comments)

https://news.ycombinator.com/item?id=9395944

phkahler2• 11 years ago

I missed that one. Thanks! BTW I'd also like an extended band over 125MHz to pick up air traffic ;-) I mentioned this to a pilot that worked at Nokia several years ago, but I guess it didn't go anywhere.

sp3322• 11 years ago

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?

meragrin• 11 years ago

According to the pictures linked to in the article, they were 2 SAW devices attached to a board. The total space they took up on the board was about 7mm x 3mm.

nine_k• 11 years ago

Their idea is that Maxwell's limit only applies to conductors, and what they use is dielectric ceramics.

throwaway8198• 11 years ago

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.)

neutronicus3• 11 years ago

(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?

neutronicus3• 11 years ago

Nah, if you read the PRL it's all classical E&M. Maxwell's Equations are Correct.

Of course, interaction of radiation with a material is all about constitutive relations anyways.

TTPrograms• 11 years ago

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 :)

neutronicus3• 11 years ago

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.

aidenn0• 11 years ago

Every cellphone I've disassembled has the 2.4GHz antenna not on-chip, but in the case. I've seen PCB antennas as well, but not on-chip whenever efficiency matters.

lightlyused• 11 years ago

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

emcrazyone• 11 years ago

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.

ramanan2• 11 years ago

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...

upofadown• 11 years ago

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...

New Theory Leads to Gigahertz Antenna on a Chip

Related Stories