Design of Self-Injection-Locked Radar System for Birds’ Wingbeat Frequency Detection

Wingbeat frequency (WBF) is an important biological feature for flying birds, used for species classification and activity observation. To develop a handheld system for WBF detection, a 2.4-GHz, short-range continuous-wave radar system is proposed in this paper. By utilizing the self-injection locked radar architecture and joint time-frequency analysis, this system is able to detect WBF on a flying bird from a distance up to 18 m. Several experiments, including identifying species in a mixed group and distinguishing the target from the clutter, are demonstrated with bionic birds. The measurements with real flying birds are also conducted in both indoor and outdoor scenarios. This proposed radar system can be used in the laboratory environment or in the wild, showing a great potential for biological study.