High-Efficiency Hexagonal-Shaped Quad Element MIMO Antenna for Terahertz Applications

A quad element multiple-input-multiple-output (MIMO) antenna with improved impedance bandwidth of 0.131 THz (0.349–0.480 THz) by using defected ground structure (DGS) is proposed for terahertz applications. The four elements are placed orthogonally to one another to reduce mutual coupling and envelope correlation coefficient (ECC). The average isolation of the proposed MIMO antenna is 25 dB. The performance characteristics of antenna are calculated in terms of ECC, diversity gain (DG), mean effective gain (MEG), total active reflection coefficient (TARC), isolation, and channel capacity loss (CCL), and the obtained values are 0.05, 9.98 dB, ±3 dB, −5 dB, −10 dB, 0.4 bits/s/Hz, respectively. Each antenna has a realized gain of 5.45 dBi with an average total efficiency of 89%. Further analysis of path loss in free space, atmospheric absorption, and roughness factor in indoor surfaces for THz communication are also studied in the proposed antenna. The proposed MIMO antenna is designed on a Rogers RO4003 substrate having a dielectric constant of 3.55, and a loss tangent of 0.0027 with a dimension of 700 × 700 × 55 mm³. The designed MIMO antenna is suitable for high speed short distance communication, video-rate imaging, biomedical imaging, sensing, and security scanning in the THz frequency band.