In this paper, a quadband MIMO diamond-shaped antenna with two highly isolated elements is proposed and discussed. A novel metamaterial cell-inspired decoupling parasitic structure is deployed between the two antenna elements to achieve high isolation greater than 20 dB in the frequency bands of interest. Moreover, the design adopts a defected ground structure and open-ended multiple diamond-shaped branches for multiband characteristics, enabling the proposed MIMO to cover several modern wireless applications. The performance metrics of the proposed MIMO antenna are validated by evaluating various diversity parameters such as envelope correlation coefficient (ECC), diversity gain (DG), total active reflection coefficient (TARC), and channel capacity loss (CCL). This antenna is fabricated on an FR4 substrate with a compact size of 12 × 30 × 1.524 mm (0.082λ 0 × 0.204λ 0 × 0.001λ 0, λ 0 is the wavelength at 2.04 GHz). With the edge-to-edge separation distance of 0.053λ 0 between the antenna elements, its prototype is experimentally measured using a two-port Rohde & Schwarz ZVA50 Vector Network Analyzer. The port-to-port isolation is about −20.87 dB, −23 dB, −25.93 dB, and −25.22 dB for 2.3 GHz, 3.18 GHz, 4.08 GHz, and 5.42 GHz frequency bands, respectively. Also, the proposed MIMO antenna exhibits good diversity performances with the ECC < 0.005, DG > 9.99, and TARC<−10 dB making it an outstanding candidate covering 4G/LTE, 5G NR sub-6 GHz n40/n41/n77/n78, Wi-Fi, WiMAX, ISM, WBAN, Bluetooth, MBAN, WiBro, C-V2X, and UWB applications.

中文翻译：

---

用于移动无线应用的具有超材料单元启发的去耦寄生元件的紧凑型四频带双端口天线

在本文中，提出并讨论了一种具有两个高度隔离元件的四频段 MIMO 菱形天线。在两个天线元件之间部署了一种新颖的超材料单元启发的去耦寄生结构，以在感兴趣的频带中实现大于 20 dB 的高隔离度。此外，该设计采用有缺陷的地面结构和开放式多个菱形分支以实现多频带特性，使所提出的 MIMO 能够覆盖多种现代无线应用。通过评估各种分集参数，如包络相关系数 (ECC)、分集增益 (DG)、总有源反射系数 (TARC) 和信道容量损失 (CCL)，验证了所提出的 MIMO 天线的性能指标。该天线是在 12 × 30 × 1 的紧凑尺寸的 FR4 基板上制造的。λ 0× 0.204λ 0× 0.001λ 0,λ 0是 2.04 GHz 处的波长）。边到边间距为 0.053λ 0在天线元件之间，其原型是使用两端口罗德与施瓦茨 ZVA50 矢量网络分析仪进行实验测量的。对于 2.3 GHz、3.18 GHz、4.08 GHz 和 5.42 GHz 频段，端口间隔离度分别约为 -20.87 dB、-23 dB、-25.93 dB 和 -25.22 dB。此外，所提出的 MIMO 天线表现出良好的分集性能，ECC < 0.005、DG > 9.99 和 TARC<-10 dB，使其成为涵盖 4G/LTE、5G NR sub-6 GHz n40/n41/n77/n78、 Wi-Fi、WiMAX、ISM、WBAN、蓝牙、MBAN、WiBro、C-V2X 和 UWB 应用。