A terahertz multiband metamaterial based rectangular loop antenna with 2×2 split ring resonator arrays and photonic band gap structures

The THz frequency band, ranging from 0.1 THz to 10 THz, is gaining increasing attention dueto its ability to provide high bandwidth, making it ideal for a wide range of emerging applications, including high-speed wireless communication systems. However, designing wireless devices for this band requires meeting stringent criteria such as sustainability, environmental resilience, flexibility, and cost-effectiveness. These challenges have driven the exploration of new materials and advanced design strategies to optimize performance while fulfilling these essential requirements. This study presents the design of a THz antenna that integrates Metamaterial (MTM) structures, 2 × 2 Split-Ring Resonator (SRR) arrays, and Photonic Band Gap (PBG) structures to enhance its overall performance. The proposed rectangular loop antenna, featuring compact dimensions of 240 µm × 230 µm × 45 µm for Kapton and 255 µm × 355 µm × 45 µm for Quartz Fabric, exhibits a multiband response with distinct resonances centered at 0.47 THz, 0.85 THz, and 1.1 THz for the Kapton-based design, and at 0.5 THz and 0.88 THz for the Quartz Fabric-based design. These responses effectively cover the 0.4–1.2 THz frequency range. The multiband behavior of the antenna significantly broadens its potential applications across various fields, including biomedical imaging, security and threat detection, THz spectroscopy, THz communications, non-destructive testing (NDT), and agriculture and food quality monitoring. Furthermore, the use of environmentally friendly and cost-effective materials, such as single-walled carbon nanotubes (SWCNTs), offers a promising pathway toward the development of sustainable, high-performance antennas. The antenna exhibits excellent impedance matching, with S11 values ensuring efficient energy transfer and minimal reflection across the operating frequency range. A comprehensive parametric study reveals significant bandwidth improvements, with Kapton achieving a bandwidth of 45–51 GHz and a realized gain of 2.95 dBi, while Quartz Fabric achieves 45–48 GHz with a realized gain of 3.71 dBi. These results confirm that the integration of MTM and PBG structures substantially enhances the antenna’s performance in terms of bandwidth, gain, and efficiency.