High-isolation ultra-wideband H-slotted two element MIMO antenna for 6G and terahertz applications

This paper presents a high-performance, ultra-wideband H-slotted two-element MIMO antenna designed for terahertz (THz) and 6G applications. The proposed antenna is implemented on a polyimide substrate and resonates at 5.5747 THz, achieving an impedance bandwidth of 4.573 THz with a peak gain of 10.93 dB. It also exhibits a very low envelope correlation coefficient (ECC) of 0.00066, with channel capacity loss (CCL) in the range of 0.001–0.02 bits/s/Hz, a total active reflection coefficient (TARC) below −10 dB, and a radiation efficiency of 90.12%. An equivalent RLC model was developed to complement the full-wave CST simulations and enable circuit-level analysis. The model provides insight into the resonance behavior, impedance-matching characteristics, and mutual coupling mechanisms of the compact two-port MIMO configuration. The design incorporates a parasitic decoupling structure (PDS) to reduce mutual coupling and improve isolation (≥−44.17 dB). Parametric studies examining patch dimensions, slot geometry, and substrate thickness further validate the impact of structural parameters on resonance, bandwidth, and gain. The combined analyses demonstrate that the proposed antenna is well suited for high-speed, low-latency THz communication, THz imaging, and IoT applications.