Ayra Wang

City University, in collaboration with Nanjing University of Science and Technology, has unveiled a groundbreaking programmable periscope designed to detect drones operating out of sight, even when blocked by towering buildings.

The development is in line with chief executive John Lee Ka-chiu's proposal to develop a low-altitude economy, as outlined in his policy address in October.

Chair professor Guo Yongxin from the university's department of electrical engineering described the periscope as a significant advancement toward safer drone operations in Hong Kong's densely-populated urban environment.

"In bustling urban landscapes, ensuring safety from drones has taken a remarkable leap forward with this innovative programmable metasurface periscope," he said.

Equipped with a low-cost, ultra-thin metasurface, the periscope can modulate the amplitude, phase and polarization of surrounding light, allowing for more accurate detection of obscured drones.

The research team has made it more insensitive to wave angles by adding a full-resonant-structure-based metasurface cell, which effectively eliminates errors in radar wave direction estimations.

Guo said angle sensitivity issues with existing metasurfaces had previously hindered the transition from theoretical models to practical radar systems.

"Our new technology is significantly more insensitive to wave angles, paving the way for the practical design of metasurface-aided radar systems," he said.

Also, the programmable metasurface periscope is not only cost-effective to produce but also easy to deploy, making it an ideal solution for integration into conventional radar systems to expand coverage areas.

Guo Yongxin explains the mechanics of how the periscope works.

Drone-detecting periscope out of sight in cityscapes