In this paper, an ultra-sensitive metamaterial terahertz sensor is proposed. The resonance sensor is designed based on a novel double corrugation form to enhance the ability of the sensor in the terms of sensitivity, Q-factor and the maximum sensible thickness of an analyte. The introduced structure can support the spoof surface plasmon and can resonate strongly at the tuned frequencies. Moreover, the structure of the terahertz sensor is investigated thoroughly from different points of view including frequency shifts due to variations in the thickness or refractive index of the analyte. In addition, the sensitivity of the sensor is approximated with a biharmonic fitting function for different combinations of refractive index and analyte thickness as “sensitivity surface”. The sensor shows the maximum sensitivity of 1.75 THz/RIU for refractive index between 1–1.2 with a maximum thickness of 80 μm. Moreover, the simulation results approved that the double corrugation on the metal stripe improves the electromagnetic field interaction in the metal part greatly in comparison with the previously reported works. According to this work, the proposed structure can be applied for terahertz sensing with more abilities to sense even thicker biologic tissues.

In this paper, a novel terahertz (THz) spectroscopy technique and a new graphene-based sensor is proposed.The proposed sensor consists of a graphene-based metasurface (MS) that operates in reflection mode over a broad range of frequency band (0.2 − 6 THz) and can detect relative permittivity of up to 4 with a resolution of 0.1 and a thickness ranging from 5 m to 600 m with a resolution of 0.5 m. To the best of author's knowledge, such a THz sensor with such capabilities has not been reported yet. Additionally, an equivalent circuit of the novel unit cell is derived and compared with two conventional grooved structures to showcase the superiority of the proposed unit cell. The proposed spectroscopy technique utilizes some unique spectral features of a broadband reflection wave including Accumulated Spectral power (ASP) and Averaged Group Delay (AGD), which are independent to resonance frequencies and can operate over a broad range of the spectrum. ASP and AGD can be combined to analyse the magnitude and phase of the reflection diagram as a coherent technique for sensing purposes. This enables the capability to distinguish between different analytes with high precision which, to the best of author's knowledge, has been accomplished for the first time.

This paper presents a fully-transparent and novel frequency selective surface (FSS) that can be deployed instead of conventional glass to reduce the penetration loss encountered by millimeter wave (mmWave) frequencies in typical outdoorindoor (O2I) communication scenarios. The presented design uses a 0.035 mm thick layer of indium tin oxide (ITO), which is a transparent conducting oxide (TCO) deposited on the surface of the glass, thereby ensuring the transparency of the structure. The paper also presents a novel unit cell that has been used to design the hexagonal lattice of the FSS structure. The dispersion and transmission characteristics of the proposed design are presented and compared with conventional glass. The presented FSS can be used for both 26 GHz and 28 GHz bands of the mmWave spectrum and offers a lower transmission loss as compared to conventional glass without any considerable impact on the aesthetics of the building infrastructure. Index Terms-mmWave, transmission surface, frequency selective surface (FSS), transparent conductor (TC), indium tin oxide (ITO).

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