When it comes to antennas, size matters
Good things come in small packages. This is especially true in the world of portable wireless communications systems. Cell phones, wearables, and implantable electronics have shrunk over time, which has made them more useful in many cases. But a critical component of these devices–the antenna–hasn't followed suit. Researchers haven't been able to get them much smaller, until now.
In a paper published online Tuesday in Nature Communications, Nian Sun, professor of electrical and computer engineering at Northeastern, and his colleagues describe a new approach to designing antennas. The discovery enables researchers to construct antennas that are up to a thousand times smaller than currently available antennas, Sun said.
"A lot of people have tried hard to reduce the size of antennas. This has been an open challenge for the whole society," Sun said. "We looked into this problem and thought, 'why don't we use a new mechanism?'"
Traditional antennas are built to receive and transmit electromagnetic waves, which travel fast–up to the speed of light. But electromagnetic waves have a relatively long wavelength. That means antennas must maintain a certain size in order to work efficiently with electromagnetic radiation.
Instead of designing antennas at the electromagnetic wave resonance–so they receive and transmit electromagnetic waves–researchers tailored the antennas to acoustic resonance. Acoustic resonance waves are roughly 10 thousand times–smaller than electromagnetic waves. This translates to an antenna that's one or two orders of magnitude smaller than even the most compact antennas available today.
Since acoustic resonance and electromagnetic waves have the same frequency, the new antennas would still work for cell phones and other wireless communication devices. And they would provide the same instantaneous delivery of information. In fact, researchers found their antennas performed better than traditional kinds.
Tiny antennas have big implications, especially for Internet of Things devices, and in the biomedical field. For example, Sun said the technology could lead to better bioinjectible, bioimplantable, or even bioinjestible devices that monitor health.
One such application that neurosurgeons are interested in exploring is a device that could sense neuron behavior deep in the brain. But bringing this idea to life has stumped researchers, until now.
"Something that's millimeters or even micrometers in size would make biomedical implantation much easier to achieve, and the tissue damage would be much less," Sun said.
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