DESIGN OF A FOUR-ELEMENT MIMO ANTENNA WITH LOW MUTUAL COUPLING IN A SMALL SIZE FOR SATELITTE APPLICATIONS

In this paper, a compact planar mono-band multiple input multiple output (MIMO) antenna with four monopole elements is presented for X-band satellite applications (7.2–7.8 GHz). The MIMO antenna resonates at 7.5 GHz, with high isolation (more than 26 dB) between its ports. It consists of a four closely arranged symmetric monopole antennas with edge-to-edge distance of 7.2 mm (0.18λ). In the top face, different forms are loaded at the rectangular patch. A U-shaped slot defected ground structure (DGS) has embedded in the ground plane. The prototype of the proposed MIMO antenna is simulated, fabricated, and measured to examine the performance of this antenna in terms of S parameters, radiation patterns, envelope of correlation coefficient (ECC), and diversity gain (DG). As a result, the presented antenna has a high isolation (S12 < −26 dB) at 7.5 GHz with an impedance bandwidth of 430 MHz (7.28 GHz–7.71 GHz), which covers the X-band applications. The diversity gain is about 10, and the envelope correlation coefficient of antenna is less than 0.02 which means that the antenna has high performance at the resonance frequency.