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A tunable dual-band terahertz (THz) dielectric-based metamaterial (MM) sensor that is highly sensitive and capable of detecting six different viruses is investigated in this article. The proposed absorber provides near-perfect absorption (Abs) at two narrow resonances, 3.659 and 4.656 THz, by using a circular ring resonator made of silicon and a square-shaped graphene (Gr) ring. The Gr’s chemical potential can be modified to achieve tunability and controllability. The strong coupling between Gr and resonant structure results in high sensing parameters, such as a high $S$ of 3.29 and 3.28 THz/RIU, figure of merit (FOM) of 470.78 and 293.84 RIU $^{-1}$ , and $Q$ of 480 and 371.42 in the first and second bands, respectively. The proposed absorber’s distinguishing features include its ultra-thin structure, polarization insensitivity, narrow Abs bandwidth, and high-quality factor. In addition, the absorber is unaffected by the input electromagnetic (EM) wave’s polarization angle.

In this paper, a two port circularly polarized (CP) MIMO Cylindrical Dielectric Resonator Antenna (CDRA) with Quad-band response is designed for terahertz (THz) applications. This antenna is new since MIMO DRA antennas in the THz frequency range have never been described before. Also, by the varying graphene potential of the antenna, isolation between the two antennas is increased and CP tuning can be achieved which is another unique feature of this proposed antenna at THz region. The proposed DRA generates two higher order modes (HEM11δand HEM12δ). The 3 dB Axial Ratio Bandwidth (ARBW) of 8.22, 2.48, 3.67 and 5.67% is achieved at four resonant frequencies. Various MIMO performance parameters are evaluated and these parameters are within acceptable limits. Advantages of the proposed design are quad response, higher order modes generation, CP tuning and good isolation between the ports. The tunability of graphene material allows it to provide CP responses in the frequency region that is most useful in biomedical applications. The use of a CP antenna in a THz biomedical application can improve system sensitivity by reducing polarisation losses and aligning them. All these features make the proposed MIMO DRA potentially suitable for THz applications.

By integrating multiple graphene-based geometric shapes, a unique absorber is proposed in this research, which achieves absorption peaks at 10 resonant frequencies, with an average absorption rate of 97.23% at terahertz frequency. The proposed structure consists of circular, triangular, square, pentagonal, and hexagonal ring-shaped absorbers to achieve multiband absorption. The proposed absorber is polarization-insensitive and has a wide incidence angle tolerance. Furthermore, increasing the graphene chemical potential value increases absorption while also tuning the resonance frequency. Additionally, this proposed configuration provides ultrawideband response at first band, with an absorption bandwidth percentage of 88.52. Two graphene-based absorbers are designed: one with geometric shapes that are in contact with one another and the other with geometric shapes that are not in contact with one another. Several investigations are exhibited on these two models to find the perfect combination of absorbers. The unique feature of this research is its novel, to the best of our knowledge, design and modeling, which provide absorption peaks at 10 resonant frequencies and also tuning of resonant frequency. All of these characteristics and findings distinguish the proposed multiband graphene-based absorber, which is well suited for terahertz applications.