Wireless communication is one of the most important technologies of the modern world, enabling us to connect with each other and access information anytime and anywhere. However, as the demand for faster and more reliable wireless services increases, so does the challenge of designing and deploying antennas that can handle the complex and dynamic radio environment.
Antennas are devices that transmit and receive electromagnetic waves, such as radio waves, microwaves, and light waves. The performance of an antenna depends on its shape, size, direction, and surface properties, which determine how it interacts with the incoming and outgoing waves. For optimal wireless communication, antennas need to be able to adapt to different frequencies, directions, and environments, which can vary depending on the location, time, weather, and interference.
However, most conventional antennas are fixed and rigid, meaning they cannot change their shape or direction to suit different scenarios. This limits their efficiency and versatility, especially for applications that require high-frequency, high-bandwidth, and multi-directional communication, such as 5G, 6G, satellite, radar, and IoT.
To overcome this limitation, researchers have been developing reconfigurable antennas that can alter their shape and properties in response to external stimuli, such as voltage, temperature, light, or humidity. These antennas can achieve better performance and functionality than fixed antennas, as they can dynamically adjust to the optimal configuration for each situation.
One of the most promising types of reconfigurable antennas is the shape-shifting antenna, which can change its physical form and geometry to modify its radiation pattern and frequency response. Shape-shifting antennas can be made of flexible, elastic, or smart materials that can bend, stretch, fold, or transform under certain conditions.
Some examples of shape-shifting antennas are:
- Helical antenna: A helical antenna is a wire antenna that is wound into a helix shape, forming a hollow cylinder. The helical antenna can change its length and diameter by pulling or pushing the cylinder, which affects its radiation pattern and frequency range. A helical antenna can operate in two modes: normal mode and axial mode. In normal mode, the antenna radiates in all directions around the cylinder, while in axial mode, the antenna radiates in a narrow beam along the axis of the cylinder. A helical antenna can switch between these two modes by changing its shape, making it suitable for applications that require both omnidirectional and directional communication, such as satellite and ground crew communication. A team of researchers from the American University of Beirut and Stanford University designed a bi-stable helical antenna that can collapse into a ring shape for axial mode and extend into a tube shape for normal mode.
- Origami antenna: An origami antenna is a flat antenna that can fold into different shapes, following the principles of origami, the art of paper folding. The origami antenna can change its surface area and curvature by folding or unfolding, which affects its radiation pattern and polarization. An origami antenna can also create multiple resonant modes by forming different geometries, such as a square, a triangle, or a star. An origami antenna can be useful for applications that require compact, lightweight, and multifunctional antennas, such as wearable devices, drones, and robots. A team of researchers from Princeton University designed a shape-shifting origami antenna array based on a folded paper box called a waterbomb. The antenna array can change its shape and orientation by inflating or deflating, which allows it to create a reconfigurable and adaptable radar imaging surface.
- Liquid metal antenna: A liquid metal antenna is an antenna that is made of liquid metal, such as gallium or mercury, that can flow and deform under an electric field. The liquid metal antenna can change its shape and size by applying different voltages, which affects its radiation pattern and frequency response. A liquid metal antenna can also merge or split into multiple segments by controlling the electric field, which enables it to create multiple radiation modes. A liquid metal antenna can be advantageous for applications that require high conductivity, low loss, and large deformation, such as biomedical devices, smart skins, and metamaterials. A team of researchers from North Carolina State University designed a shape-shifting liquid metal antenna that can be injected into elastomeric microchannels. The antenna can be twisted and bent without affecting its performance, as the mechanical properties are dictated by the elastomer and not the metal.
Shape-shifting antennas are a breakthrough for wireless communication, as they offer a new level of flexibility, adaptability, and functionality that cannot be achieved by conventional antennas. By changing their shape and properties, shape-shifting antennas can improve the performance and efficiency of wireless systems, as well as enable new applications and possibilities. Shape-shifting antennas are expected to play a key role in the future of wireless communication, especially for the emerging 6G technology and beyond.
