According to a recent study, new membrane-based antennas could be nearly 100 times smaller than the most compact antennas available today. And these antennas could find use in portable wireless communications systems, including wearable electronics, smartphones, bio-implantable, antennas, bio-injectable antennas, bio-ingestible antennas, and the IoT.
State-of-the-art compact antennas are designed to resonate at specific wavelengths. But their miniaturization is limited to roughly one-tenth of their resonant wavelengths. The new antennas developed by researchers at Northeastern University and their collaborators can now be shrunk to sizes as small as one-thousandth of the wavelength they aim to receive and transmit at - without any degradation in performance.
These antennas consist of thin membranes made up of two different kinds of films. Its piezomagnetic iron-gallium-boron layers convert mechanical oscillations to magnetic signals and vice versa. They are paired with piezoelectric aluminum nitride films, which convert mechanical oscillations to electrical signals and vice versa.
When these membranes receive electromagnetic signals, their magnetic layers sense the magnetic fields of these electromagnetic waves. This causes the membranes to vibrate, which piezoelectrically generates a voltage. Conversely, in order for the antennas to transmit, they vibrate. This causes the magnetic layers of the membranes to generate a magnetic current that radiates electromagnetic waves.
The sizes of these magnetoelectric antennas depend on the wavelengths of the acoustic vibrations they operate with; instead of the electromagnetic signals they receive and transmit. Because these acoustic wavelengths are about 100,000 times shorter than their corresponding electromagnetic wavelengths, these new antennas can be much smaller than conventional antennas.
According to the research leader Nian-Xiang Sun, this acoustic antenna concept changes the fundamental principle on which antennas have been designed for over a century, and can lead to dramatically compact antennas with an improved performance. In experiments, these nano-electromechanical system (NEMS) antennas could receive and transmit at VHF and UHF radio frequencies. In addition, they are completely passive, requiring simple electronics and no battery.
Future researches will now attempt to improve antenna performances through new materials, new designs and better fabrication processes. According to researchers, these were the first magnetoelectric antennas that have been demonstrated and have a lot of room for improvement.
Click here for the research report.
