Carbon nanotubes show promise for 5G antennas

Carbon nanotubes applied onto devices are as efficient as copper for wireless applications, claim researchers at Rice University’s Brown School of Engineering.

The Rice lab of chemical and biomolecular engineer Matteo Pasquali tested antennas made of so-called “shear-aligned” nanotube films, which are also claimed to be more flexible and tougher than their copper counterparts. The researchers discovered that not only were the conductive films able to match the performance of commonly used copper films, they could also be made thinner to better handle higher frequencies.

The results detailed in Applied Physics Letters take forward the lab’s previous work on antennas based on carbon nanotube fibres. Lead author Amram Bengio has founded a company to further develop the material.

At the target frequencies of 5, 10 and 14 gigahertz, the antennas easily held their own with their metal counterparts, Bengio said in a statement. “We were going up to frequencies that aren’t even used in Wi-Fi and Bluetooth networks today, but will be used in the upcoming 5G generation of antennas.”

To make the films, the Rice lab dissolved nanotubes, most of them single-walled and up to eight microns long, in an acid-based solution. When spread onto a surface, the shear force produced prompts the nanotubes to self-align.

According to Bengio although gas-phase deposition is widely employed as a batch process for trace deposition of metals, the fluid-phase processing method lends itself to more scalable, continuous antenna manufacturing.

Rice University said the test films were about the size of a glass slide, and between one and seven microns thick. The nanotubes are held together by strongly attractive van der Waals forces, giving the material mechanical properties far better than those of copper.

The researchers said the new antennas could be suitable for 5G networks but also for aircraft, especially unmanned aerial vehicles, for which weight is a consideration; as wireless telemetry portals for downhole oil and gas exploration; and for future IoT applications.

“There are limits because of the physics of how an electromagnetic wave propagates through space,” Bengio said. “We’re not changing anything in that regard. What we are changing is the fact that the material from which all these antennas will be made is substantially lighter, stronger and more resistant to a wider variety of adverse environmental conditions than copper.”

Image: Metal-free antennas made of thin, strong, flexible carbon nanotube films are as efficient as common copper antennas (Credit: Jeff Fitlow/Rice University)