A Low-Cost Beam Scanning FMCW Radar Prototype Based on CP LWA Array

This paper presents a low-cost Frequency-Modulated Continuous-Wave (FMCW) radar measurement prototype based on a 1×8 circularly polarized leaky-wave antenna array. By integrating frequency and phase scanning, the prototype achieves three-dimensional beam control without a conventional phased array. The antenna employs a dual-layer Spoof Surface Plasmon Polariton (SSPP) structure combined with a Butler matrix to generate six fixed beam directions at -28° to 28°. The main beam can be continuously steered from –48° to 10° via frequency tuning, significantly reducing hardware complexity and implementation cost The proposed measurement prototype adopts a linear frequency modulated continuous wave scheme, enabling simultaneous range and angle estimation through frequency-domain processing. For ranging, fast Fourier transform and coherent integration of the beat signal achieve 9.4 cm accuracy at a maximum detection distance of 13.8 m. For angle estimation, frequency stepping controls the beam direction, providing a theoretical angular resolution of approximately 1.87°. The prototype also supports velocity measurements with a resolution of 0.01 m/s and a maximum unambiguous velocity of ±0.075 m/s. Experimental validation demonstrates accurate detection of multiple targets at varying directions and distances, with centimeter-level error. The results confirm the proposed prototype’s practicality and integration potential for spatial sensing and target localization applications.