Innovative W-Band Through-Wall Radar With Sector Scanning: Utilizing Traveling Wave Tubes for Enhanced Penetration

This article presents the development of an innovative high-power W-band through-wall radar (TWR) system, operating at 93.6–96 GHz, which synthesizes the linear frequency modulation (LFM) signal with a bandwidth of 2.4 GHz, achieving high distance accuracy of 6.25 cm and enabling sector area detection via mechanical scanning. To address the significant attenuation issue caused by high-frequency electromagnetic waves (EM waves) passing through walls, the proposed design utilizes an original solution: a high-gain traveling wave tube (TWT) with an output power of up to 53 dBm, effectively compensating for wall loss. The system can be deployed remotely up to a maximum distance of 5 m from the wall and scan the area within 10 m behind the wall. Attenuation of W-band EM waves through seven distinct wall materials was rigorously tested and calculated using the free-space measurement method, providing detailed insights into the system’s design. Furthermore, a W-band waveguide band-pass filter was simulated and fabricated based on computer numerical control (CNC) technology for filtering and image frequency suppression. The filter exhibits an in-band low insertion loss of 0.64 dB and a return loss better than 15 dB. Multiple through-wall experiments were conducted in both static and scanning modes, and the test results conclusively demonstrate that the proposed W-band TWR with high power output exhibits strong through-wall detection capabilities. This study addresses the gap in TWR technology operating within the millimeter-wave band, presenting a feasible solution for attaining high-range resolution, and effectively mitigating the substantial hurdle of high-frequency wall loss.