Аннотация
Multi-band MIMO antennas that concurrently support both lower frequency bands and millimeter-wave (mmWave) bands are crucial for next-generation wireless communication systems, such as 5G and beyond. These systems necessitate compact, high-performance antennas to achieve high data rates and robust spatial diversity. The deployment of multiple-input multiple-utput (MIMO) antennas can fulfill these requirements. However, the integration of multiple frequency bands within a compact MIMO antenna system frequently results in significant mutual coupling, which adversely affects antenna performance metrics such as gain, radiation pattern, and efficiency. To address this issue, this paper present design of an 8-element multi-band MIMO antenna that integrates sub-6 GHz and mmWave operation using a compact, fractal-inspired patch and a mutual coupling reduction technique. Initially, a single-element antenna inspired by a fractal shape geometry was designed with a partial ground plane on a RO4300C substrate. To achieve higher data rates and increase capacity, the single antenna element is then expanded to an 8-element MIMO configuration. Two MIMO configurations are analysed: In the first configuration (MIMO1), all eight antenna elements are arranged without any coupling mitigation. Simulation results for MIMO demonstrate acceptable reflection coefficients and resonance characteristics at the desired frequency bands; however, high mutual coupling is observed between adjacent elements, which may negatively impact diversity performance and system capacity. To address this, a second configuration (MIMO2) is proposed by introducing a simple decoupling line between neighboring elements. The inclusion of this line significantly reduces the coupling between elements while preserving overall impedance characteristics and resonant modes. The improved isolation leads to enhanced performance consistency among elements and more reliable multi-antenna operation. This approach offers a low-complexity and effective solution for enhancing isolation in multi-band MIMO antenna systems.