Design of a high isolation tri-band MIMO antenna for coal mine applications

In this paper, a tri-band multiple-input multiple-output (MIMO) antenna with high isolation characteristic is designed and fabricated for coal mine applications. It is composed of two symmetrical trident planar monopoles which can achieve tri-band characteristics. The isolation between the elements is higher than 20 dB across the whole frequency region by firstly placing the two elements symmetrically, loading a T-shaped branch and etching two rectangular slots on the ground successively. The proposed antenna can operate at three bands, i.e., 1.85∼2.70 GHz, 3.24∼3.99 GHz and 4.65∼5.80 GHz, which simultaneously cover the operating frequency band of WiMAX, WiFi, 4G, and 5G New Radio (NR) for mining. Good agreements can be observed between the simulated and measured results. The designed tri-band MIMO antenna has the advantages of low profile, compact structure and easy to conform with the platform, thus having a broad prospect in coal mine applications.