With the ability to reconfigure themselves by folding and unfolding, origami-shaped antennas will be able to more efficiently respond to incoming electromagnetic signals.
A Georgia Tech research team was recently awarded a $2 million dollar grant from the National Science Foundation (NSF) for their unique concept of making compact and efficient antennas by implementing the techniques used in origami paper-folding. With the ability to reconfigure themselves by folding and unfolding, these moldable antennas will be able to respond more efficiently to incoming electromagnetic signals.
View: Origami Antennas
Across various platforms exists a desirable need to miniaturize large antenna structures to help decrease costs. “There is also a need for antenna structures to readjust in real-time without power, immense technology, and electronic exploration,” says Dr. Manos Tentzeris, a professor at Georgia Tech’s School of Electrical and Computer Engineering. “Traditionally, people have reconfigured electronics and antennas through the use of switches or micro-electromechanical systems (MEMS). By utilizing origami paper-folding techniques, everything can be done through the control signal, activating different ways of folding and unfolding.
Self-activation mechanisms would help the tiny antennas morph without required electronics or electrical power, and origami configurations could revolutionize the applicability of antenna structures across various markets and industries.
Because typical origami structures are expected to fold and unfold numerous times, they can be fabricated from a variety of materials, such as paper, plastics, or ceramics. “In our lab, we have used inkjet printing techniques to add conductive materials to the antenna elements,” explains Tentzeris. “We have managed to print materials, such as dielectrics, nanostructures, and conductors on virtually any substrate.” The research team is planning to test paper and fabric substrates, as well as flexible polymers and flexible organics.
Folding & Unfolding
The antenna's folding and unfolding capabilities provide an advantage in various commercial and military applications. According to Tentzeris, such antennas could be included in different types of communications equipment, as well as various sensors, portable medical equipment, electronics mounted on vehicles, flying objects, space platforms, and cognitive electronics that adjust to ambient conditions in real time.
Several potential activation mechanisms, such as harvested ambient electromagnetic energy in the air, would be used to trigger the folding once they come in contact with an incoming signal. “Power and frequency levels will be the two control parameters, either embedded into an incoming signal, which would reconfigure the origami structure itself, or have a separate control signal from some type of operator,” says Tentzeris.
When required, antenna movement could also be powered by activation beams from a special energy harvester that would collect ambient energy and transmit it to the antennas from as far away as 50 to 100 meters.
One important goal of the research team, according to Tentzeris, is to maximize the number of shapes that can be achieved in a single folding structure to help support antenna functionality. This presents a major challenge for the team because of the limited number of shapes that can be packed into a device of a certain size. “Additional mathematical study could result in being able to form 16, 32, or even more different types of antennas from a single device that’s less than an inch square when folded.”
The antenna’s lifespan is dependent on the substrate it is made from, and the type of substrate is dependent on the application. The application will also determine if some type of energy storage device needs to be designed within the hinges. Depending on the material, the energy will come from the control signal and will be connected into some form of mechanical energy, which would flip the hinges on and off.
An origami-inspired antenna could have a lifecycle of several years without any eminent deformation, however, any antenna that is designed to fold and unfold multiple times will have a shorter lifespan than one designed for a flight or space platform.
“For more low-cost applications, such as sensors, folding and unfolding of the substrate would occur more frequently, leading to material deformation and instability of the hinges,” explains Tentzeris.
Inkjet printing will be essential to the development of these specific types of antennas, and Tentzeris admits that this particular technology would not be possible without it. Special inkjet techniques developed by his team can deposit tiny antenna circuitry and support electronics, dielectrics, and nanostructures on a variety of materials such as paper, polymers, fabrics, carbon fibers, ceramics, and flexible organics. “These developments have taken place over the last five to seven years,” says Tentzeris. “They have allowed us to produce extremely low-cost prototypes.”
Tentzeris also emphasized how inkjet printing technologies have a wide range of applicability, including sensing, monitoring, local communication devices, and aviation and aerospace platforms. “The structures can be miniaturized and designed to be extremely light weight leading to the first real-world realization of very large area electronics – anywhere from square meters or even tens of square meter.”
Inkjet technologies also provide the opportunities to print different shapes, which could be used for different monitoring parameters or resolutions that would be advantageous for portable medical and monitoring devices.
“Traditionally, the fabrication of electronics involved the use of extremely high temperatures. With the use of inkjet printing, we can now fabricate electronics at room temperature,” says Tentzeris. “Not only are we printing at lower costs, but we now have the opportunity to print on virtually any material for applications up to the millimeter-wave and sub-terahertz frequency range.”
The Georgia Tech research team, along with a research team from Florida and several origamists, have many challenges to resolve during this project, including the origami shape that would allow the largest number of folding and unfolding movements. “We also need to consider the type of materials used for the antenna structure. If the antenna needs to fold and unfold multiple times, we need to pick a material that has sufficient flexibility,” says Tentzeris.
“Another challenge is identifying reliable ways to organize the control-signal enabled hinges and housing structures on 3D-printed structures,” he adds. “The third challenge would be to figure out what the best compromise would be between the extremely wide bandwidth and rugged deployment.” According to Tentzeris, he needs to figure out how to keep the structure intact when it is launched.
This article originally appeared in the November/December print issue. Click here to read the full issue.