Design of a Dual-stopband Terahertz Frequency-Selective Surface based on a Square Ring Structure
Qiannan Li, Hui Zhang, Yongjun Zhou, Jixia WuIntroduction:
In view of the practical demand for electromagnetic interference shielding in the terahertz (THz) band in actual engineering, a Frequency-Selective Surface (FSS) shielding device suitable for this band is designed.
Methods:
To achieve the dual-bandstop filtering function, this study employs the multi-layer cascading method and designs a Frequency-Selective Surface (FSS) element structure with a square ring structure as the basic resonant unit. The structure selects a low-loss liquid crystal polymer (LCP) rectangular dielectric as the substrate, and the upper and lower surfaces of the substrate are uniformly coated with square ring metal structure units with good consistency, forming a symmetrical layout to enhance the electromagnetic coupling effect.
Results:
The designed FSS features well-defined dual stopbands, covering the frequency ranges of 0.987-1.186 THz and 1.846-2.175 THz. For incident electromagnetic waves within these frequency bands, the FSS exhibits a strong shielding effect, achieving an average attenuation of approximately −48 dB and effectively suppressing unwanted terahertz signals.
Discussion:
The angle stability, polarization stability, and structural parameters of the FSS were analyzed using ANSYS HFSS simulation software. The angle stability of the FSS reached 45°, and it is polarization-insensitive with stable performance under TE/TM polarizations. By adjusting the relevant parameters of the unit structure, its band-stop performance can be tuned.
Conclusion:
The designed FSS has excellent dual-stopband performance. It also has a simple, easy-to-process structure, and with its 45° angular stability, polarization insensitivity, and adjustable band-stop performance, it holds broad application prospects in high-speed THz communication, precision electromagnetic shielding, and security inspection fields.