The article presents a 2-port multiple-input multiple-output (MIMO) antenna array designed for millimeter-wave band operation, specifically optimized for Vehicle-to-Everything (V2X) applications. To enhance performance, a novel approach employing two types of metasurfaces on a single plate is utilized. The first metasurface, based on a loop structure, aims to improve the frequency bandwidth, while the second metasurface, utilizing a composite right/left-handed (CRLH) design, focuses on reducing mutual coupling. These two steps result in an improved frequency bandwidth exceeding 45% and a decreased structure width of about 50% compared to other designs. Notably, the compact nature of these metasurfaces, measuring approximately 32 × 3 mm, is a significant feature that reduces manufacturing costs. The arrayed antenna, with 20 series elements, is suitable for medium-range radar in V2X applications, although our method is generally applicable to other ranges. Additionally, the radiation pattern exhibits a 40-degree beam rotation within the frequency bandwidth, making it well-suited for V2X applications. The results demonstrate impressive diversity performance, with a consistent maximum gain of 16 dB across the entire frequency bandwidth of approximately 68 GHz to 82 GHz, representing an 18.2% coverage.

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