Abstract:
High-frequency wireless electromagnetic waves suffer significant transmission loss in curved roadways and at roadway corners, resulting in signal blind spots. To address this issue, a metasurface reflection technique was proposed to enhance wireless signal coverage and mitigate signal blind spots. The traditional cross-shaped structure of the metasurface array unit was improved, and a 330° phase shift range and a well-defined linear phase shift curve were achieved by embedding multi-level nested rectangular resonators and adjusting the internal cross dimensions. Based on this, a metasurface reflection device was designed and fabricated. Using the 5.8 GHz ultra-high frequency band, simulations and field tests were conducted to evaluate the signal enhancement performance of the metasurface reflection device in the inclined curved section and the intersection of main and auxiliary sections in the Qingshuixi roadway. The results showed that, with fixed transmission and reception distances and different transmission antenna structures, the installation of the metasurface reflection device enhanced both the signal-to-noise ratio and the reference signal receiving power to varying degrees in both the inclined curved section of roadways and the intersection of main and auxiliary sections. The enhancement was most significant when using a linearly polarized horn directional antenna, with a maximum gain of 13 dB in received reference signal power. The analysis highlighted challenges in applying passive metasurface reflection technology in mine roadways, including difficulties in aligning the incident wave angle, focusing the beam, and achieving sufficient wave incidence distance. Based on the test results, fixed installation of metasurface reflection devices at roadway intersections is recommended for point-to-point transmission blind spot mitigation.