A compact MIMO antenna used for LTE terminals with high isolation

A compact MIMO antenna with high isolation for LTE commercial frequency band (2.57 - 2.62 GHz) is presented. The proposed MIMO antenna consists of two winding antennas with similar shape but different direction placed and each of which has the dimension of 15.5 mm ×34 mm. The separation between the two antennas is 5 mm (about 4.3% of the wavelength at 2.6 GHz). In order to achieve high isolation performance for such a small separation, an electromagnetic band gap structure is used between two antennas. It consists of an array in which each element is combined by a shaped concentric circle and via hole covered with copper on its inner surface. These elements can act as a high resistance circuit to prevent electromagnetic transmission by which to achieve a high isolation. The isolation of the proposed MIMO antenna can even reach 30 dB at the targeting frequency band.