Researchers at the Johns Hopkins Applied Physics Laboratory (APL) have introduced an antenna that changes shape in response to temperature. Using cutting-edge additive manufacturing techniques and shape memory alloys (SMAs), the team has developed a technology with transformative potential across military, commercial, and scientific applications.
The innovative design, detailed in a recent publication in ACS Applied Engineering Materials and featured in an upcoming print issue, allows the antenna to dynamically alter its shape, enabling operation across multiple radio-frequency (RF) bands. This adaptability could replace the need for multiple fixed antennas, offering new levels of operational flexibility.
RF Communication with Shape Memory Alloys
Traditional antennas are limited by their fixed shapes, which dictate their operating parameters. A shape-shifting antenna opens possibilities for dynamic RF communications, including:
- • Operating across various frequency bands with a single antenna.
- • Switching between short- and long-range communications by adjusting beamwidth.
- • Adapting in real time to spectrum availability for greater agility.
The breakthrough leverages nitinol, a shape memory alloy of nickel and titanium, which returns to a “remembered” shape when heated. While commonly used in medical devices and aerospace actuators, nitinol’s use in additive manufacturing has posed significant challenges due to its need for extensive mechanical processing to achieve the shape memory effect.
From Concept to Breakthrough
The project began in 2019 when electrical engineer Jennifer Hollenbeck, inspired by the shape-shifting technology in The Expanse series, sought to create a more versatile antenna. Collaborating with Steven Storck, APL’s chief scientist for additive manufacturing, the team embarked on a multi-year effort to overcome the limitations of 3D printing nitinol.
Initial attempts to create a shape-shifting antenna faced challenges, including rigidity and difficulty in expansion. However, with funding from APL’s internal Propulsion Grant, the team refined the design, achieving a two-way shape memory effect, where the antenna transitions between a flat spiral disk when cool and a cone spiral when heated.
Overcoming Technical Challenges
Developing the shape-shifting antenna required solving several technical obstacles:
- 1. Heating Mechanism:
The team had to design a power line capable of heating the antenna without compromising RF properties or structural integrity. RF engineer Michael Sherburne led the development of a novel power line to deliver sufficient current for this purpose. - 2. Additive Manufacturing of Nitinol:
Printing nitinol presented unique challenges, as the material’s shape memory properties caused it to deform during the printing process. Additive manufacturing engineers Samuel Gonzalez and Mary Daffron spent weeks optimizing the processing parameters to achieve consistent results. - 3. Material Composition:
By modifying the ratio of nickel to titanium, the team enhanced the two-way shape memory effect, enabling the antenna to switch between shapes at specific temperatures.
Wide-Ranging Applications and Future Plans
The shape-shifting antenna holds potential across various fields:
- • Military Operations: Enables special operators to adapt to dynamic communication needs in the field.
- • Telecommunications: Supports mobile network adaptability and expanded coverage.
- • Space Exploration: Offers lightweight, adaptive solutions for deep-space missions.
APL is pursuing patents for the shape-adaptive antenna, the innovative power line, and associated control methods. Additionally, the team aims to expand the technology to different SMA materials and optimize production for broader use across additive manufacturing systems.
Innovation in Action
“The shape-shifting antenna capability demonstrated by this APL team will be a game-changing enabler for many applications requiring RF adaptability in a compact configuration,” said APL Chief Engineer Conrad Grant.
This achievement underscores the power of multidisciplinary collaboration at APL, setting the stage for advancements that could reshape communication technologies across industries.
Source: jhuapl.edu