The circular patch antenna prototype changes its frequency from high to low. (Image Credit: Jeff Xu/Penn State)
Reconfigurable antennas will serve a crucial role in future communication networks, such as 6G. However, existing reconfigurable antennas have some downfalls. For example, they deteriorate in high or low temperatures, require servicing, and have power limitations. Penn State electrical engineers overcame those issues by combining electromagnets with a compliant mechanism, a similar mechanical engineering concept for a bow and arrow or binder clips.
“Compliant mechanisms are engineering designs that incorporate elements of the materials themselves to create motion when force is applied, instead of traditional rigid body mechanisms that require hinges for motion,” said corresponding author Galestan Mackertich-Sengerdy, who is both a doctoral student and a full-time researcher in the college’s School of Electrical Engineering and Computer Science (EECS). “Compliant mechanism-enabled objects are engineered to bend repeatedly in a certain direction and to withstand harsh environments.”
Applying it to a reconfigurable antenna causes the compliant mechanism-enabled arms to bend predictably, resulting in operating frequency changes. “Just like a chameleon triggers the tiny bumps on its skin to move, which changes its color, a reconfigurable antenna can change its frequency from low to high and back just by configuring its mechanical properties, enabled by the compliant mechanism,” said Sawyer Campbell, co-author in the study.
This design replaces origami design technologies, which aren’t as robust, reliable, and lack high-power handling capability. “Origami antenna designs are known for their compact folding and storage capabilities that can then be deployed later on in the application,” Mackertich-Sengerdy said. “But once these origami folded structures are deployed, they usually need a complex stiffening structure so that they don’t warp or bend. If not carefully designed, these types of devices would suffer environmental and operational lifetime limitations in the field.”
The engineers used electromagnetic simulation software to illustrate and design the circular patch antenna prototype. Afterward, the 3D-printed and ran tests for fatigue failure and frequency and radiation pattern fidelity in the anechoic chamber, which has electromagnetic wave-absorbing material insulation, preventing signal interference on the antennas. While the prototype is nearly the size of a palm, it can be scaled up to achieve higher frequencies or increased in size for lower-frequency applications.
“The paper introduces compliant mechanisms as a new design paradigm for the entire electromagnetics community, and we anticipate it growing,” said co-author Douglas Werner, John L. and Genevieve H. McCain, Chair Professor of EECS. “It could be the branching-off point for an entirely new field of designs with exciting applications we haven’t dreamed of yet.”
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