Wideband High Gain Meatsurface-Based 2×2 MIMO antenna with Highly Isolated Ports for Sub-6 GHz 5G Applications

Abstract

A high gain and wideband MIMO antenna with highly isolated ports allows the 5G technology to provide reliable wireless communication with high data rate, low latency, increased channel capacity, high signal quality, low power, and high data throughput while maintaining the penetration rate. This study presents the design and simulation of two wideband, high gain, metasurface-based 2 x 2 MIMO antennas operating from 2.85 to 4.2 GHz for 5G applications, which satisfy the 5G requisites. The radiating elements of the two MIMO antennas use the aperture coupled feeding technique with a dumbbell shape slot, a metasurface layer that utilizes the surface wave propagation, and a truncated square patch with two U-shaped slots to attain wideband and high gain performance. The power of the feed radiates through the dumbbell shape slot to illuminate the radiating patch, which allows better manipulation of the coupled power compared with the rectangular slot. The proposed MIMO structure places four identical radiating elements like a 2 x 2 matrix with a rotation of 0°, 90°, 180°, and 270° to produce orthogonal electromagnetic waves, which improves the isolation between ports. Two vertical and horizontal strip slots are engraved on the ground as the decoupling structure to decrease the mutual coupling among the radiating elements. Besides, the aperture-coupled feeding technique increases the independence between the radiating elements by isolating the radiating patches and the microstrip feed lines. The CST and HFSS software are used to simulate the antennas. According to the CST and HFSS simulation results, the highest gain values of the first MIMO design vary from 7.6 to 8.9 dBi and 8.8 to 9.25 dBi over the operational bandwidth, respectively. It achieves less than -32 dB isolation, almost 10 dB diversity gain, and below 0.0002 ECC. However, it experiences 2.2 to 5 dBi back lobe levels. The second MIMO antenna is proposed to kill the back lobe levels and increase the gain while providing high isolation and low mutual coupling. The second antenna put a metal plate at 20 mm beneath the first antenna to achieve peak gain values from 9.5 to 11.75 dBi, isolation below -20 dB, almost 10 dB diversity gain, and ECC (Envelope Correlation Coefficients) values below 0.0012 over 2.8 to 4.2 GHz. The achievements show that the radiating elements of both MIMO antennas work independently with minimal mutual coupling, which increases the channel capacity. The comparison with other studies' achievements indicates that the proposed MIMO antennas are among the best candidates for 5G based systems, such as IoT (Internet of Things) applications and vehicular communications.