Conformal Wide-Angle Scanning Leaky-Wave Antenna for V-Band On-Body Applications (2407.13644v3)

Abstract: Wearable on-body millimeter-wave (mmWave) radars can provide obstacle detection and guidance for visually impaired individuals. The antennas, being a crucial component of these systems, must be lightweight, flexible, low-cost, and compact. However, existing antennas suffer from a rigid form factor and limited reconfigurability. This article presents a low-profile, fast scanning leaky-wave antenna (LWA) operating in the unlicensed V-band (57-64 GHz) for on-body applications such as lightweight portable frequency modulated continuous wave (FMCW) radars. The novel meandering microstrip design allows independent control of gain and scanning rate (rate of change of main beam pointing direction with frequency). Experimental results show that the LWA achieves a realized gain above 10 dB with a fan-beam steering range in the H-plane from -35{deg} to 45{deg} over the operating frequency band, while the half power beamwidth (HPBW) is within 20{deg} in planar condition. To assess the on-body applicability, the antenna's performance is evaluated under bending. When placed on the knee (corresponding to 80 mm radius), the beam steers from -25{deg} to 55{deg} with a maximum realized gain degradation of 1.75 dB, and an increase of HPBW up to 25{deg}. This demonstrates the LWA's robustness in conformal conditions, while maintaining beam-forming and beam-scanning capabilities. Simulations confirm that the LWA's ground plane minimizes user exposure, adhering to international guidelines. Finally, we demonstrate a 2-D spatial scanning by employing an array of twelve LWAs with phased excitation, enabling beam-forming in the E-plane from -50{deg} to 50{deg}, while the HPBW remains below 20{deg}. Mutual coupling analysis reveals that isolation loss and active reflection coefficient remain below 15 dB throughout the operating band.