Optically Invisible Antennas Could Empower 5G Devices

Researchers at Pohang University of Science & Technology (POSTECH) developed a way to build optically invisible antennas that could be embedded within superresolution displays. The Antenna-on-Display (AoD) technology could provide an alternative to conventional antenna technology for 5G devices that will require multiple antennas, while maintaining a streamlined design.

To build the antenna, the researchers used diamond-grid-shaped 2000-Å-thick Ag-alloy electrodes on a glass substrate to form a transparent diamond-grid antenna. They achieved optical invisibility by implementing identical dummy grids around the antenna region. A multilayer schematic was designed in order to expand the antenna element into a phased-array configuration.

Researchers at POSTECH have developed what they believe to be the first Antenna-on-Display for 5G devices. Courtesy of POSTECH.

The researchers believe that the new antennas will help expedite the deployment of 5G devices. They said that 5G relies on millimeter-wave frequencies that are at least one order of magnitude higher than current 4G LTE and Wi-Fi. Consequently, the signal attenuation at millimeter-wave becomes much greater, leading to the need for a “cluster” of antennas to form a dense electromagnetic beam at certain directions, similar to how microscopes work. This means that 5G wireless devices will require dozens of antennas. The AoD technology could be used for the large number of 5G antennas required for high-definition OLED and LCD displays, eliminating the trade-off between ergonomics, aesthetics, and technology.

The technology was developed in collaboration with industry partners Dong-Woo Fine Chem, SK Telecom, LG Electronics, Keysight Technologies, and Y Tech Co. Ltd. The research team developed a transparent thin film for the AoD with Dong-Woo Fine Chem. LG Electronics integrated the AoD within their cellular device prototype, and this prototype was used to conduct 5G trials at 28 GHz with SK Telecom. The POSTECH research consortium has completed field testing of the technology on a 5G Android smartphone platform.

Professor Wonbin Hong is holding the Antenna-on-Display smartphone. Courtesy of POSTECH.

“This is the first step of our collaborative research,” professor Wonbin Hong said. “Similar to how on-screen touch sensors redefined wireless devices, the Antenna-on-Display has the potential to trigger various possibilities for 5G and beyond. We expect it will contribute not only to creating innovative 5G smartphone concepts but serving as an enabling technology for many ideas beyond our imagination.”

The research was published in IEEE Transactions on Antennas and Propagation (https://ieeexplore.ieee.org/document/8649588).