Broadband graphene–metal hybrid polarization-insensitive FSS with a wide tuning range at terahertz frequency Diptiranjan Samantaray, Sambit Kumar Ghosh, Nikhil Kumar, Ajeet Singh Verma, Raghvenda Kumar Singh, et al. Applied Optics, 2026 In this paper, a broadband graphene–metal hybrid frequency-selective surface (FSS) is designed and numerically investigated for tunable band-pass-filtering applications in the terahertz range. The unit cell of the proposed FSS comprises a gold nanostructure and a distinctive graphene pattern. These layers are separated by a thin silicon dioxide (SiO 2 ) layer and are uniformly applied on both sides of a thick foam block. The results demonstrate that the proposed FSS exhibits broadband transmission in the range of 7.71–9.89 THz. This corresponds to a fractional bandwidth of 24.77%. The originality of the proposed work, to our knowledge, lies in the incorporation of the dual-patterned graphene layers in the design, enabling the proposed FSS to provide an extended tunable filtering response. The design facilitates the preservation of continuity in the graphene pattern, promoting an efficient way of electrical biasing of the device. Simulations reveal that it can achieve a tunable transmission band from 6.67 to 10.20 THz (∼41.85%), with an adequate out-of-band attenuation when the graphene’s chemical potential is adjusted between 0 and 1.5 eV. The design is analyzed in a detailed manner with the aid of various simulated results, which have been subsequently validated by an in-house equivalent circuit model approach. The proposed FSS is polarization independent and exhibits angular stability under oblique incidence up to 40° for both transverse electric and transverse magnetic wave polarizations. Owing to these unique features, it has huge potential to be employed in EM shielding, 6G communication systems, and cognitive radio-based futuristic devices.
Design of metasurface-inspired high-gain and low-profile LHCP antenna Manoj Kumar Shrivastava, Ripudaman Singh, Diptiranjan Samantaray, Anil Kumar Gautam, Amit Kumar Singh International Journal of Microwave and Wireless Technologies, 2025 This paper presents a metamaterial-inspired, left-handed circularly polarized (LHCP), high-gain, and miniaturized antenna with a radiation efficiency of 92.8%. A properly arranged metamaterial containing a 4 × 4 array of unit cells is placed on the ground plane of the microstrip antenna to increase the antenna’s gain up to 12.8 dBi at 10.3 GHz. Both the unit cell and the antenna are designed on an FR4 substrate with a loss tangent of 0.02 and a relative permittivity of 4.4. The overall dimensions of the designed antenna are 0.88λ0 × 0.88λ0 × 0.052λ0, where λ0 is the free-space wavelength at 9.8 GHz. The simulated bandwidth of the prototype antenna is 2.8 GHz (9.9–12.7 GHz), while the measured bandwidth is 3.2 GHz (9.8–13 GHz). The maximum simulated and measured gains are 14.4 and 12.8 dBi, respectively, at frequencies of 10.4 and 10.3 GHz. Achieving such high gain in a small LHCP antenna is the novelty of our antenna design. The bandwidth of the proposed antenna lies within the upper X-band and lower Ku-band. Therefore, this antenna is suitable for applications such as weather monitoring and air traffic control systems.
