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Engineers have made wireless antennas much smaller, which could enable applications such as brain implants:
Antennas receive information by resonating with EM waves, which they convert into electrical voltage. For such resonance to occur, a traditional antenna's length must roughly match the wavelength of the EM wave it receives, meaning that the antenna must be relatively big. However, like a guitar string, an antenna can also resonate with acoustic waves. The new antennas take advantage of this fact. They will pick up EM waves of a given frequency if its size matches the wavelength of the much shorter acoustic waves of the same frequency. That means that that for any given signal frequency, the antennas can be much smaller.
The trick is, of course, to quickly turn the incoming EM waves into acoustic waves. To do that, the two-part antenna employs a thin sheet of a so-called piezomagnetic material, which expands and contracts when exposed to a magnetic field. If it's the right size and shape, the sheet efficiently converts the incoming EM wave to acoustic vibrations. That piezomagnetic material is then attached to a piezoelectric material, which converts the vibrations to an oscillating electrical voltage. When the antenna sends out a signal, information travels in the reverse direction, from electrical voltage to vibrations to EM waves. The biggest challenge, Sun says, was finding the right piezomagnetic material—he settled on a combination of iron, gallium, and boron—and then producing it at high quality.
The team created two kinds of acoustic antennas. One has a circular membrane, which works for frequencies in the gigahertz range, including those for WiFi. The other has a rectangular membrane, suitable for megahertz frequencies used for TV and radio. Each is less than a millimeter across, and both can be manufactured together on a single chip. When researchers tested one of the antennas in a specially insulated room, they found that compared to a conventional ring antenna of the same size, it sent and received 2.5 gigahertz signals about 100,000 times more efficiently [open, DOI: 10.1038/s41467-017-00343-8] [DX], they report today in Nature Communications.
(Score: 1, Interesting) by Anonymous Coward on Wednesday August 23 2017, @02:52PM (2 children)
Is the government has had spying devices capable of transmitting and recieving acoustic signals in the mhz to ghz range for years requiring 100k times less transmit/receive power than our current anti-spy devices have been looking for.
Yeah, I think people should be concerned. Especially if it is small enough to mass manufacture on something the size of a chip.
(Score: 1, Informative) by Anonymous Coward on Wednesday August 23 2017, @03:32PM (1 child)
The Thing: https://en.wikipedia.org/wiki/The_Thing_(listening_device) [wikipedia.org]
(Score: 2) by realDonaldTrump on Wednesday August 23 2017, @04:47PM
Very interesting! Russian technology is fantastic. That guy Theremin was very, very talented, he invented the musical instrument too. The theremin. The music for The Thing from Another World was played on one. The movie came out the same year they found the bug. In 1951. Maybe the bug is named for the movie! 🇺🇸
(Score: 0) by Anonymous Coward on Wednesday August 23 2017, @06:01PM
...a real buzz!
(Score: 2) by pvanhoof on Wednesday August 23 2017, @07:26PM
So "EM waves are fluctuations in an electromagnetic field, and they travel at light speed", and, "Acoustic waves are the jiggling of matter, and they travel at the much slower speed of sound—in a solid, typically a few thousand meters per second. So, at any given frequency, an EM wave has a much longer wavelength than an acoustic wave."
How exactly are they transferring, or, converting, EM waves to acoustic waves? A few hundredthousand arriving at light speed consolidate to one acoustic wave traveling at sound speed?
(Score: 0) by Anonymous Coward on Wednesday August 23 2017, @08:47PM
This is essentially an electrostatic speaker in reverse??