A team in China has developed an antenna for 6G networks that allows manipulation of the direction, frequency and amplitude of the radiated beam using a metasurface.
The group, led by Professor Chan Chi-hou, Acting Provost and Chair Professor of Electronic Engineering in the Department of Electrical Engineering at City University of Hong Kong (CityU), developed the sideband-free metasurface antenna using space-time-coding (STC).
One of the key features is that there are many switches on its surface, and the response of the metasurface can be changed by turning on and off the switches to control the electric current, creating a desired radiation pattern and a highly-directed beam. The space-time coding software control, which enables great user flexibility.
The metasurface antenna consists of three metal layers and two dielectric layers bonded by a thin film. A waveguide uses the top and bottom metal layers as well as the two rows of metallic vias to confine EM waves within the first substrate and a rectangular opening slot is etched on the top metal layer to couple waves into free space.
There is a total of 164 PIN diodes in the design, and all share the same negative electrode through the top metal layer of the waveguide. The 82-way voltages drive the positive electrode through the shorted vias passing from the top substrate down to the bottom one connected to an FPGA as the controller.
The antenna was inspired by the new concept of AM leaky-wave antennas that proposed in 2020 by Dr Wu Gengbo, postdoctoral fellow at CityU’s SKLTMW. The waveguide-integrated metasurface antenna also provides a self-filtering phenomenon that overcomes the issue of sideband pollution found in traditional modulated metasurfaces.
“A high-directivity beam is generated at the input frequency, allowing a wide range of radiation performance without having to redesign the antenna, except for using different STC inputs,” he said.
Professor Chan, who is also Director of the State Key Laboratory of Terahertz and Millimeter Waves (SKLTMW) at CityU, said that the energy from the radiated beam of the antenna can be focused to a focal point with fixed or varying focal lengths, which can be used for real-time imaging and treated as a type of radar to scan the environment and feedback data.
“The invention plays an important role in the ISAC for 6G wireless communications,” said Professor Chan. “For example, the radiated beam can scan and duplicate an image that is similar to a real person, so that mobile phone users can talk with each other with 3D hologram imaging. It also performs better against eavesdropping than the conventional transmitter architecture.”
“We hope that the new-generation antenna technology will become more mature in the future and that it can be applied to smaller integrated circuits at lower cost and in a wider range of applications,” he said.