Addressing Bandwidth and Isolation Challenges in THz MIMO: A Dual-Band Bow-Tie Antenna for Biomedical, Pharmaceutical, and Security Applications

Terahertz (THz) MIMO antenna systems offer strong potential for next-generation sensing, imaging, and wireless communication, but practical deployment is still limited by narrow impedance bandwidth and poor inter-element isolation in compact designs. This work presents a dual-element MIMO antenna on a quartz substrate (170 × 68 µm²) that addresses both challenges using a modified bow-tie radiator with embedded rectangular slots. The slot-loading creates independent resonant paths within a single element, enabling dual-band operation at 5.12 THz and 6.78 THz without increasing footprint. Full-wave simulations (CST Microwave Studio) show a combined −10 dB bandwidth of 757 GHz, with return losses of −40.64 dB and −35.5 dB and VSWR values of 1.01 and 1.03, indicating near-ideal impedance matching. The antenna achieves peak directivities of 6.22 dBi and 7.44 dBi with stable linear polarization. Inter-element isolation remains better than −30 dB across the band without any decoupling structures. MIMO performance metrics further confirm strong diversity behavior, with an ECC of 1.25 × 10⁻⁷, CCL of 6.84 × 10⁻¹⁵ bps/Hz, and diversity gain of 9.99 dB, close to the theoretical limit. The proposed design serves as a compact, fabrication-compatible platform for biomedical imaging, pharmaceutical spectroscopy, security screening, and 6G MIMO communication within a single THz antenna architecture.