Radio and cell phone towers, as well as other current communication equipment, are sometimes destroyed or severely damaged when a region experiences an earthquake, flood, or other natural catastrophe. It is essential to promptly restore emergency communications to coordinate rescue and relief operations.
Assistant Professor Maria Sakovsky co-designed a portable antenna that can communicate with satellites and devices on the ground, making it easier to coordinate rescue and relief efforts in disaster-prone areas. Image Credit: Andrew Brodhead
A portable antenna created by researchers at Stanford University and the American University of Beirut (AUB) could be easily built in disaster-prone locations or used to establish connectivity in undeveloped countries.
The antenna, which was recently detailed in Nature Communications, folds up into a small size and is capable of switching between two configurations with ease to connect with satellites or ground-based equipment without drawing extra power.
The state-of-the-art solutions typically employed in these areas are heavy, metallic dishes. They’re not easy to move around, they require a lot of power to operate, and they’re not particularly cost-effective. Our antenna is lightweight, low-power, and can switch between two operating states. It’s able to do more with as little as possible in these areas where communications are lacking.
Maria Sakovsky, Assistant Professor, Aeronautics and Astronautics, Stanford University
Two Functions in One Antenna
The researchers created the antenna using a method often employed in the creation of space-based technologies. Due to fuel and space constraints, equipment going into orbit must be extremely lightweight and packed as tiny as feasible.
Once in orbit, the components unfurl into the appropriate shape for utilization. The researchers hoped that their antenna would be equally foldable and lightweight.
Made of fiber composites, a material frequently used in satellites, the antenna was created by Sakovsky and her colleagues at AUB, including Joseph Costantine, Youssef Tawk, and Rosette Maria Bichara. It has several strips of material crossing in spirals, like a child's finger-trap toy.
The conductive material that runs through the antenna emits signals, just like any other helix-based antenna does. However, because of its special structure, the researchers can alter the pattern and strength of the signals by drawing the material into longer or shorter patterns.
Sakovsky added, “Because we wanted the antenna to be able to collapse into a packable shape, we started with this structure that led us to a very untraditional antenna design. We are using shapes that have never been used on helical antennas before, and we have shown that they work.”
The antenna is a hollow ring that weighs 1.4 ounces and is a little larger than a bracelet when it is at its most compact. It is slightly over 1 inch tall and around 5 inches wide. With a high-power signal sent in a certain direction, it can connect to satellites in this configuration.
The antenna functions more like a Wi-Fi router and emits a lower-strength signal in all directions when it is extended to a height of around one foot.
It is as easy as tugging or pushing on the antenna to switch between these two settings. Since the framework snaps into place when the antenna reaches a predetermined point, these motions don't even need to be particularly precise. The particular frequencies across which those two states communicate will depend on the size and form of the antenna design.
“The frequency you want to operate at will dictate how large the antenna needs to be, but we have been able to show that no matter what frequency you operate at, you can scale this design principle to achieve the same performance,” Sakovsky stated.
The constructed prototype was put to the test at Stanford for deployment and structural performance, and at the antenna measurement facilities at AUB for its electromagnetic radiation properties.
Applications in Orbit
The antenna would only weigh around two pounds when combined with a transceiver for sending and receiving messages, a ground plane for reflecting radio waves, and other electronics to be placed in the field, according to Sakovsky.
Furthermore, because of its special dual capability, the antenna might be able to replace several larger antennas in locations where deployment is difficult.
This covers applications in impoverished and disaster-prone areas as well as, perhaps, in space. Sakovsky and her associates are thinking about modifying their concept for satellite communications, enabling spacecraft to communicate with the Earth and with each other using the same antenna.
Sakovsky concluded, “We don’t have a lot of spare operating power, volume, or mass on our spacecraft either. This holds a lot of potential for replacing multiple antennas on a satellite with a single one.”
Sakovsky is a member of the Alliance for Stanford SystemX. Other co-authors are from the American University in Beirut.
The Swiss State Secretariat for Education, Research, and Innovation financed this research.
Journal Reference
Bichara, R. M., et. al. (2023) A multi-stable deployable quadrifilar helix antenna with radiation reconfigurability for disaster-prone areas. Nature Communications. doi:10.1038/s41467-023-44189-9.