Twisting magnetic-dipole antenna at 15.4 Hz is 49,000 times more efficient than a size-matched loop
Authors demonstrated centimeter- and millimeter-scale antennas for 15.4 and 668 hertz that radiate by mechanical twisting of a magnetic dipole, with a 115-meter underwater link.
A study in Science Advances describes a radiation mechanism for miniaturized low-frequency antennas that replaces the time-varying currents of conventional antennas with the mechanical twisting oscillation of a magnetic dipole science.org
Science Advancesscience.orgOpen source ↗. The antennas are built as piezoelectrically actuated, biomimetic twisting resonators with ultrahigh mechanical quality factors. The approach is aimed at the size-efficiency trade-off that limits compact antennas.
The authors demonstrated low-frequency antennas operating at 15.4 and 668 hertz, miniaturized to centimeter and millimeter scale, respectively. Their radiation efficiencies exceed those of size-matched loop antennas by factors of 49,000 and 5000, respectively.
In an underwater cross-medium communication demonstration, the link covered 115 meters with only milliwatt-level power consumption, according to the authors. This is 99.9% less power than loop antennas use. Such antennas are needed for underwater, underground and biomedical communications, where performance is constrained by the size-efficiency trade-off. The mechanism also supports implantable wireless devices, which reached a fourfold increase in communication range at identical power consumption.
