Gaurav Saxena

In this manuscript, a compact wideband THz MIMO antenna with dimensions of 80×100×12.6 μm³ is designed on a gold-plated Rogers AD410 substrate (εr = 4.1). The antenna achieves a wide impedance bandwidth of 3.7–6.85 THz through optimized microstrip line feeding and SRR integration. The radiation performance is further improved by employing a SIW, which enhances the FBR and suppresses surface wave losses. In the MIMO configuration, the antenna supports high data rates of 10.78 Gbps (QPSK) and 56.48 Gbps (16-QAM), with a channel capacity of 8.24 bps/Hz at 20 dB SNR, outperforming conventional single-element antennas. Diversity analysis confirmed robust performance: ECC < 0.02, DG > 9.99 dB, TARC < -15 dB, and CCL < 0.25 bits/sec/Hz. The peak gain reaches 8.94 dBi with an FBR of 8 at 6.75 THz, alongside ~51% radiation efficiency across the band. Two resonance peaks at 4.5 and 6.0 THz exhibited high quality factors (>60), which are suitable for bio-medical sensing. Band-1 (4.50-4.63THz) shows the sensitivity 3.413 THz/RIU with a FoM of 19.63, whereas resonant Band-2 achieves an average sensitivity of 219.86 THz/RIU with a FoM of 11.37 for urine bio-sensor. These results establish the antenna as a promising candidate for 6G-enabled IoT, near-field communication, and bio-sensing applications.

In this chapter, we have a simple design for a terahertz graphene patch metasurface absorber (MSA) for RCS reduction as well as high isolation in a 2-elements MIMO antenna which is composed of a diamond-shaped structure in which the centre has concentric circles. We have designed a metasurface absorber (MSA) which is polarisation insensitive for both transverse magnetic and transverse electric waves. For high-speed terahertz (THz) applications, a graphene hexagonal microstrip feed MIMO antenna is proposed in this study. The antenna is designed with a closely coupled patch with a size of 1550 × 1000 × 150 µm³ using RT5880 as a dielectric substrate having relative permittivity of 2.2. MIMO antenna contains 2 elements which are orthogonally oriented with a 180^° angle between them. The ground of the antenna has a C looped-shaped decoupling structure, which provides high isolation. The patch is of graphene which provides high thermal conductivity. The antenna has a wide impedance bandwidth, spanning 2 THz (0.1–2 THz) with an isolation more than 20dB and reaching maximum peak gain over 10dBi. The improved isolation and the low RCS of the MIMO antenna make it suitable for terahertz wave radar, health care, cancer detection, aerospace applications, military application in radiolocation and 6G services.

In this article, a UWB metasurface absorber is designed for a frequency range of 6.75GHz-14.5GHz. The absorber consists of a simple unit cell size of 0.265λ ₀ ×0.265λ ₀ ×0.103λ ₀ on a single-layer FR-4 substrate with a thickness of 3.1mm. It has greater than 90.0% absorbance. Next, an X-band circularly polarized MIMO antenna is developed on an FR-4 substrate with a thickness of 1.0mm. The antenna has dimensions of 0.966λ ₀ ×0.766λ ₀ ×0.053λ ₀ . The MIMO antenna’s S-parameters, radiating efficiency, gain, and diversity parameters are further indicators of its usefulness. The designed metasurface is also employed as a tool to enhance the peak gain of the proposed MIMO antenna up to 8.8dBi and reduce radar cross-section by 18dBm ² , by placing the metasurface array superstrate and down correspondingly. The simulated and measured results for the metasurface and antenna, both individually and collectively, are more harmonious, demonstrating the applicability of the suggested designs for IoT over satellite, military applications, and identifying blood clots in CT-scan applications.

In this article, two elliptical-ovel-shaped cylindrical dielectric resonator based wideband Graphene inspired reconfigurable metasurface absorber is designed on diffused quartz substrate having a relative permittivity of 3.75 and conductivity 2200Kg/m3 with height of 25μm. This metasurface having gold plated ground in microstrip with 5μm which is essential by calculating skin depth at 2.0THz frequency. Two elliptical ovel shaped patches with Graphene plated having built in potential varies 0-2.5eV and relaxation time 1.0ps at 290oK. By changing the relaxation time of Graphene 0.1ps-0.3ps its resonance frequency also varies i.e., reconfigurable property they provide without adding any active i.e., PIN diode components. The proposed MS is designed having a dimension of 100×100μm2 is designed on a microstrip. This MS works in the range of 1.6-2.38THz having more than 90% absorbance with two transmission zero at 2.1THz and 2.3THz having high Q ˃ 50 which is used to determine the sensitivity where the proposed MS used as a sensor to determine hemoglobin (Blood Glucose level) and urine (Uric acid) by changing their refractive index from 1.34-1.43. Maximum sensitivity achieved at 2000GHz/RIU and average sensitivity for hemoglobin and urine sensing achieved 833.33GHz/RIU, FOM-8.33 and 4277.7733GHz/RIU, FOM-555.55 respectively.

In this paper, a rectangular-shaped wideband dielectric resonator Graphene inspired electronic band gap (EBG) based complementary split ring resonator (CSRR) loaded miniaturized THz MIMO antenna is designed having a dimension of 56×56×3.6μm 3 is designed on a Roggers RO3035 substrate with a relative permittivity of 3.6 and loss tangent 0.0015. This antenna works in the range of 6.0THz-12.5THz (70.76%) with a peak gain of 7.68 dBi for used in medical imaging and THz wireless near field applications. This composite DRA materials having Silicon (εr = 11.1) based cylindrical dielectric and cylindrical Graphene disk to be stacked on rectangular radiated antenna having height of 13.5µm and 0.2µm to improve the impedance bandwidth as well as gain of the antenna from 5.24dBi to 7.68dBi. Firstly single-element gold plated rectangular shaped antenna is transformed into a two-element MIMO antenna with mushroom-shaped EBG structure is deployed for improving the isolation between two antenna elements as well as to improve the maximum front-to-back ratio (FBR) 35.2 at 8.52THz which enhance the gain/directivity of the antenna. CSRR is loaded to obtained band notch characteristics for avoiding the interference between near wireless devices in the span of 10.6-10.8THz. Graphene disk having 3µm height put on Silicon (εr = 11.1) based cylindrical DRA provides high gain and improved the impedance bandwidth for achieving wide bandwidth from 6.0THz-12.5THz. The proposed MIMO Antenna performance has been judged by antenna parameters like gain, return loss, isolation between two antenna elements, diversity parameters like ECC, DG, TARC, Mean Effective Gain (MEG), Channel Capacity Loss (CCL) and found proposed DRA-MIMO antenna suitable for wide band nano/optical communication in 6G for IoT and bio-medical sensing application with avg. sensitivity 805.33GHz/RIU and Figure of Merit(FOM)-3.37 for hemoglobin and 805.55GHz/RIU and Figure of Merit(FOM) 10.55 for urine sensing applications .

In this paper, a rectangular-shaped wideband dielectric resonator Graphene inspired electronic band gap (EBG) based complementary split ring resonator (CSRR) loaded miniaturized THz MIMO antenna is designed having a dimension of 56×56×3.6μm3 is designed on a Roggers RO3035 substrate with a relative permittivity of 3.6 and loss tangent 0.0015. This antenna works in the range of 6.0THz-12.5THz (70.76%) with a peak gain of 7.68 dBi. This composite DRA materials having Silicon (εr = 11.1) based cylindrical dielectric and cylindrical Graphene disk to be stacked on rectangular radiated antenna having height of 13.5µm and 0.2µm to improve the impedance bandwidth as well as gain of the antenna from 5.24dBi to 7.68dBi. Firstly single-element gold plated rectangular shaped antenna is transformed into a two-element MIMO antenna with mushroom-shaped EBG structure is deployed for improving the isolation between two antenna elements as well as to improve the front-to-back ratio (FBR). CSRR is loaded to obtained band notch characteristics for avoiding the interference between near wireless devices in the span of 10.6-10.8THz. Graphene disk having 3µm height put on Silicon (εr = 11.1) based cylindrical DRA provides high gain and improved the impedance bandwidth for achieving wide bandwidth from 6.0THz-12.5THz. The proposed MIMO Antenna performance has been judged by antenna parameters like gain, return loss, isolation between two antenna elements, diversity parameters like ECC, DG, TARC, Mean Effective Gain (MEG), Channel Capacity Loss (CCL) and found proposed DRA-MIMO antenna suitable for wide band nano/optical communication in 6G for IoT and bio-medical sensing application.