Concurrent Detection of Vibration and Distance Using Unmodulated CW Doppler Vibration Radar With An Adaptive Beam-Steering Antenna

A new method to concurrently detect the vibration and distance with a beam-steering antenna is proposed. Unmodulated CW Doppler vibration radar is able to detect the distance to the target with a fast-switching beam-steering antenna. An adaptive beam-steering 2 × 2 phase-array antenna is developed for a 5.8-GHz Doppler noncontact vibration radar system. The antenna with -27 ° to +20 ° beam-steering angles shows 85 ° coverage for detection. The size of this adaptive beam-steering antenna is exactly the same as the original 2 × 2 fixed-beam antenna. This adaptive beam-steering antenna with electronic switches provides 0.83-ms fast-switching rate for steering the beams. Furthermore, different dc offsets due to different propagation paths are measured under different beam-steering angles. The distance to the target can be accurately extracted with less than 8% error by analyzing the dc offsets of the baseband signals at different beam-steering angles. This system successfully detects the architectural deformation caused by a seismic simulator.