Minimum Return Loss Research Articles

Performance analysis of optimum Chebyshev filters at microwave frequencies

The paper suggests that optimum Chebyshev filters present an excellent choice for microwave filter design, as this approximation offers minimum return loss in the half-power passband, provides a maximum cutoff slope, and maintains low sensitivity in the passband. A comparative analysis is conducted with the chained-function filters to demonstrate the efficacy of this approximation, since chained-function filters also utilize Chebyshev polynomials to shape the filter’s characteristic function. The optimum Chebyshev filter, along with two chained-function filters, each of the sixth-degree, are realized, simulated, and compared as lowpass stepped impedance filters with a half-power passband of 1 GHz. After a detailed comparison, it is concluded that the optimum Chebyshev filter outperforms, or at least matches, the performance of the chained-function filters. This suggests that the optimum Chebyshev filter can effectively replace chained-function filters in all applications, offering a superior solution.

Development of CuS/C composite for microwave absorption using lignin biopolymer

In recent decades, electronic devices have become a crucial component of everyday life and an increasingly important aspect of national security. However, despite their convenience, the emission of electromagnetic (EM) radiation from these devices has created a pollution issue that demands urgent attention. In this study, the properties and performance of CuS/C composites as EM wave-absorbing materials were examined. The main technique employed involved modifying the surface structure and properties of a lignin biopolymer via a fiber laser to derive porous carbon as a microwave absorber in the X-band range. Flower-like CuS microspheres were integrated into the porous carbon to improve the electrical conductivity and promote internal reflections. In addition, multilayer microwave absorbers were developed using CuS/C/epoxy composites with varying weight percentages, which were fabricated through refluxing and annealing techniques. The return losses of the absorbers in single- and multi-layer modes were optimized by modified local particle swarm optimization (MLPSO). The minimum average return loss improved to −15 dB (96.8%) by optimization in the 4-layer mode with a thickness of 1.8 mm. The optimum absorption peak in the 3-layer structure was −54.52 dB at a frequency of 8.83 GHz. The shielding effectiveness assessments indicated that the CuS/C/epoxy composite significantly improved the shielding capabilities of porous C and CuS, resulting in an increase of the shielding effectiveness threshold (SET) from less than 2 dB in lignin to more than 10 dB in CuS/C/epoxy.

Полосковый резонатор СВЧ с объемным кристаллом: экспериментальные характеристики и определение эффективной диэлектрической проницаемости

The paper presents the results of an experimental study and modeling of the frequency characteristics of a resonator in the form of two strip vibrators, separated by a large gap and covered with a bulk lithium niobate crystal. A metal electrode with a floating potential is installed on the upper surface of the crystal. The frequency dependences of the scattering matrix coefficients of a stripline resonator were measured in the frequency range up to 3 GHz. Electrodynamic analysis was carried out in the COMSOL Multiphysics numerical simulation environment. A comparison was made of experimental and numerical results, which showed good qualitative agreement between the transmission coefficients and reflection coefficients. Resonant oscillations were obtained at two or three frequencies depending on the location and orientation of the crystal. It has been established that at the first resonant frequency the electrode acts as a screen. The absence of an electrode leads to the disappearance of resonance. The simulation carried out in COMSOL made it possible to estimate the effective dielectric constant of the resonator corresponding to the values of the resonant frequencies. The calculation of electromagnetic fields made it possible to establish the types of waves corresponding to resonant frequencies. Knowing the type of waves and estimating the relative dielectric constant made it possible to construct an algorithm for a refined iterative procedure for calculating the values of the resonant frequencies and the effective dielectric constant of the resonator. The possibility of using resonators as single-link bandpass filters with a passband of about 1%, insertion loss of –1.1 dB and minimal return loss of –28 dB at the center frequency is shown.

Design of high gain MMIC amplifier for LEO satellite communication systems

In this paper, we present a novel design of S-band monolithic microwave integrated circuit (MMIC) amplifier based on GaAs Mesfet HFET-1102 transistor used in radiofrequency (RF) and microwave communications system. Basing on Chebyshev gain response an analytical method is used to design two stages lumped microwave amplifier. The matching networks constituted by lumped elements are transformed to T inductive networks and the resulting amplifier is optimized using RF simulator software. Thelumped optimized amplifier is then transformed to distributed amplifier and implemented on Rogers TMM3 substrate, largely used in microwave circuits. The proposed MMIC distributed amplifier is stable in the frequency band (2–4 GHz) and excellent performances are obtained in terms of very high gain reaching a peak of 34.23 dB, minimum input return loss (S11) of −8.85 dB at f=2.62 GHz, minimum output return loss (S22) of −12.21 dB at f=2.05 GHz and very good output/input isolation (S12) lower than −51.99 dB. For its excellent performances, the proposed MMIC distributed amplifier, is very suitable for use in space telecommunications as in Low Earth Orbit (LEO) satellites onboard receivers where the high gain amplifier is very important to assure the success of the space missions.

Low-Power Energy Harvesting Voltage Doubler Using CTLs Based on Inverse Class-F Configuration Compatible with Fifth Generation

This paper introduces a highly efficient and low-power inverse class-F voltage doubler (VD) designed for radio frequency (RF) energy harvesting systems. Specifically tailored for mid-band 5G technology, the VD is designed for operation within the 1240–1300 MHz satellite band. The innovative design employs an inverse class-F architecture, incorporating a λ/8\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\lambda /8$$\\end{document} short-ended transmission line (TL) connected to the diode anode and a (λ/12\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\lambda /12$$\\end{document}) open-ended transmission line linked to the input of the voltage doubler. This configuration aims to reshape voltage and current waveforms, effectively reducing losses and series resistance in the diode. Dual-coupled transmission lines (CTLs) are utilized to provide passive voltage boosting at low-input power levels. The suggested voltage doubler is implemented using RO4003C substrate material with a dielectric relative permittivity (εr\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\upvarepsilon }_{r}$$\\end{document}) of 3.38 and a thickness of 0.81 mm. Measured results demonstrate a minimum input return loss of − 29.3 dB at 1.25 GHz, operating seamlessly within a frequency band from 1.18 to 1.32 GHz. The measured conversion efficiency is 45.2% at an input power (Pin) of − 4dBm. Furthermore, the peak RF–DC efficiency reaches 50% at an input power of 0dBm. Simulated results predict a remarkable conversion efficiency of 60% and 68.7% at − 4dBm and 0 dBm, respectively. In addition to its exceptional performance, the suggested voltage doubler exhibits an experimental DC output voltage of 0.53 V at Pin=-10dBm\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$P_{{{\ ext{in}}}} = - 10{\ ext{dBm}}$$\\end{document} and a saturated DC voltage of 3.4 V at an input power of 10dBm under a load terminal resistance of 8 KΩ. Finally, the dimensions of the proposed voltage doubler are 25.3×10.5mm2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$25.3 \ imes 10.5 {\ ext{mm}}^{{2}}$$\\end{document}.

Compact and high gain cup-shaped 4-Port MIMO antenna using low profile material for the sub-6 GHz, IoT and military applications

The article introduces a novel design of a miniaturised and high-gain 4-Port MIMO antenna ingeniously crafted as a cup. The evolution of the radiating structure, achieved through meticulous iterations involving alterations to the patch element’s shape and feedline modifications, underscores the commitment to optimal performance. Leveraging parametric analysis, which includes strategic adjustments to the ground layer’s length, incorporation of vertical and horizontal slots, and the addition of a parasitic patch in the top layer, our proposed framework spans the spectrum from 1 GHz to 14 GHz. The antenna exhibits a tripartite frequency response at 4.6 GHz, 8.7 GHz, and 13 GHz, showcasing a peak bandwidth of 5.5 GHz and a minimum return loss of −24.22 dB. Remarkably, the design achieves a peak gain of 8.32 dB, coupled with stellar performance in diverse parameters such as ECC, MEG, TARC, CCL, and DG. Constructed with low-profile FR4 material, the antenna thoroughly compares simulated and measured results, affirming its robust performance. This innovative architecture, poised for Sub6GHz, IoT, and military applications, not only pushes the boundaries of antenna design but also stands out as a significant advancement in the field.

A Case Study of Nelder Mead Simplex Optimization Algorithm: Trade-Offs of Sprienski Fractal Bowtie Antenna Parameters

In this study, tri-band antenna design adapted for wireless communication, Internet of Things (IoT) and RFID systems is examined. The simulation results indicate that the proposed antenna has three distinct frequency bands. Band 1 (lower band) covers the frequency range of 1.64-1.78 GHz with a resonance frequency of 1.7 GHz. Band 2 covers the range of 3.06-3.9 GHz with a resonance frequency of 3.4 GHz with a high gain of 10 dBi and a radiation efficiency of 92% for long-range communication. Band 3 radiates from 6.25 to 7.6 GHz with a resonance frequency of 6.62 GHz, which is suitable for higher-frequency applications. The antenna design is simulated and analyzed regarding S11, VSWR, gain, radiation efficiency, and bandwidth. Especially, Band 2 (mid-band) provides notable performance, with its 10 dBi gain and 92% efficiency, which makes the proposed antenna an ideal structure for high-data-rate, long-distance communication systems, and 5G (midband) applications. This study also employs the Nelder-Mead Simplex algorithm to observe the optimization of the physical parameters of the proposed antenna via multiple objective functions. The optimization results outlines that longer the arm length of the proposed antenna causes to decrease the resonance frequency of Band 3. Addition to this, the gain is higher with the lower arm length except for the arm length of 90.467 mm and flare angle of 64.77o. That’s, the trade-off condition occurs between minimum return loss and gain. At this point, it can be concluded from this optimization algorithm results that each objective function should be evaluated separately due to this trade-off condition.

Development of high performance microwave absorption modified epoxy coatings based on nano-ferrites

With the rapid spread of wireless technologies and increasing electromagnetic energy, electromagnetic waves (EMW) have become a severe threat to human health. Therefore, minimizing the harmful effects of electromagnetic wave radiation is possible through the development of high-efficiency EMW absorption coatings. The aim of this work was to generate microwave absorbance coatings containing synthesized nano-CuFe2O4 and nano-CaFe2O4. Firstly, nano-CuFe2O4 and nano-CaFe2O4 were synthesized using the sol–gel method. Then, their structure, electrical, dielectric, and magnetic properties were investigated to find out the possibility of using these materials in high-frequency applications (e.g., microwave absorbance coatings). After that, two dosages (2.5 wt% and 5 wt%) of nano-CuFe2O4 and nano-CaFe2O4 were incorporated into epoxy resin to prepare modified epoxy resin as microwave coatings. The dielectric studies show that the AC conductivity of the prepared samples is high at high frequencies. Additionally, the magnetic properties reveal a low coercivity value, making these samples suitable for high-frequency devices. The microwave results illustrate that adding nano-ferrites with high content enhances the absorption characteristics of the tested films. The results showed that the two films have two absorption bands with RL < –10 dB ranging from 10.61 to 10.97 GHz and from 10.25 to 11.2 GHz. The minimum return loss achieved for the two cases is −13 and −16 dB, respectively. Indicating that the film coated with CuFe has a better absorption value than the one coated with CaFe.

Design and diversity performance analysis of C shape engraved miniaturised, and high gain Quad-Port MIMO antenna for 5 G and P2P communication

The 4-Port multiband operated MIMO antenna operating at 4 GHz, 6 GHz and 9 GHz is proposed to target the 5 G and P2P communication applications. The electrical size of the 4-Port antenna structure is 0.8λ × 0.48λ. The unique shape of a single radiating patch element is identified by engraving a circular shape patch element and modifying the shape of the feedline. The optimisation in terms of return loss was achieved based on the defected ground structure and changing radius of different elements of the patch structure. The 2-Port and 4-Port MIMO antenna structures are designed using the FR4 substrate and their return loss is compared and examined. The proposed design provides a minimum return loss of −22 dB, peak bandwidth of 2.25 GHz, peak gain of 4.67 dB, and normalised directivity of 187°. Different MIMO diversity parameters are analysed. The proposed design provides an envelope correlation coefficient of 0.01, Diversity gain near 10 dB, mean effective gain of almost zero, channel capacity loss of almost zero and Mean effective gain within the acceptable range. The overall Performance of the Proposed Design is compared with other 4-Port design structures and it represents healthy gain, multiple band response and proper diversity parameters making it suitable for the 5 G and P2P communication applications.

A compact fifth-order SIW BPF based on TSV technology with high selectivity

In this paper, a fifth-order Substrate Integrated Waveguide (SIW) filter using Through-Silicon Via (TSV) technology is proposed. The slots on the top and bottom redistribution layers (RDL) of the filter provide negative coupling and a finite transmission zero (FTZ). This effectively improves stopband attenuation. Asynchronous tuning is applied to the coupling path of this component. The center frequency of the filter is 3.6 GHz (fractional bandwidth is 3.50 %). The minimum insertion loss is 1.58 dB, the minimum return loss is 23.6 dB, and the overall size is 1.855 × 1.316 mm2. The simulation results show that the proposed SIW filter can achieve better in-band characteristics and selectivity with the similar size or smaller size as compared to the SIW filter operating at the similar frequency.

High-Performance SAW Resonator with Spurious Mode Suppression Using Hexagonal Weighted Electrode Structure.

Surface acoustic wave resonators are widely applied in electronics, communication, and other engineering fields. However, the spurious modes generally present in resonators can cause deterioration in device performance. Therefore, this paper proposes a hexagonal weighted structure to suppress them. With the construction of a finite element resonator model, the parameters of the interdigital transducer (IDT) and the area of the dummy finger weighting are determined. The spurious waves are confined within the dummy finger area, whereas the main mode is less affected by this structure. To verify the suppression effect of the simulation, resonators with conventional and hexagonal weighted structures are fabricated using the micro-electromechanical systems (MEMS) process. After the S-parameter test of the prepared resonators, the hexagonal weighted resonators achieve a high level of spurious mode suppression. Their properties are superior to those of the conventional structure, with a higher Q value (10,406), a higher minimum return loss (25.7 dB), and a lower ratio of peak sidelobe (19%). This work provides a feasible solution for the design of SAW resonators to suppress spurious modes.

Six-element MIMO antenna structure with squared ring structure with multiband and high gain characteristics for C/X/Ku/K band applications

Using ring resonator structure, we have presented a structure of the six-element multiple input multiple output (MIMO) antenna structure. The proposed structure is numerically investigated and experimentally verified for antenna performance in the 1 to 25 GHz wideband frequency range. We have designed and verified the five antenna structure types, which consist of the various forms of ring/patch with different ground plane geometries. Various performance parameters like gain, directivity, reflections, and electric field distributions are analyzed for MIMO antennas. Essential performanceparameters observed for the MIMO antennas are also presented in this manuscript to identify the behaviour of the structure with different physical conditions. These parameters are also investigated for the identification of suitable ranges for the multi-channel transmission capability of the communication system. Return loss and Gain values are< −12 dB and ∼ 20 dBi achieved with ∼12 GHz of the operating bandwidth. Overall, the antenna offers minimum return loss values of −25 dB for the operating band of 19 to 25 GHz with anoperational bandwidth of 6 GHz. The designed antennas are tested using a ground patch and a rectangular patch in a scattered manner, and the obtained results are utilized in the Ultrawideband MIMO antenna applications. These antennas are also used in various band operations in satellite communication, including C/X/Ku/K bands.

GNR based Tapered Vivaldi antenna for THz band applications

This article presents a novel high gain Tapered Vivaldi antenna (TVA) utilizing Graphene Nano Ribbon (GNR) for the Terahertz band applications. The proposed design based on substrate extension technique and graphene hybrid metal structure to improve the radiation characteristics. It also derives the Electric and Magnetic field of graphene is systematically using FDTD numerical modeling. The reconfigurability properties of antenna can be achieved by changing the chemical potential. The result offers a minimum return loss of −58.68 dB, an impedance bandwidth of 298.84 GHz, a peak gain of 12.31 dBi, peak directivity of 13.1 dBi, and radiation efficiency of 83.63 %. The investigated results reveal the better results within the preferred frequency band. Therefore, the designed antenna can be useful for various THz applications.

Miniaturized and high gain circularly slotted 4×4 MIMO antenna with diversity performance analysis for 5G/Wi-Fi/WLAN wireless communication applications

A miniaturized with a high gain four port Multiple-Input Multiple-Output (MIMO) is presented in the manuscript. The presented design contains four radiating patch elements with a Defected Ground Structure (DGS). The shape of the radiating element is identified after the analysis of three stages. The design optimization is performed by changing the diameter of the circle loaded in the patch region and changing the length of the ground layer. The design is investigated for L, S, C, and X frequency band regions. The structure is designed using flame-retardant glass-reinforced epoxy laminate material (FR4) substrate material. The physical size of the four-port structure is 78x50 mm2. Three resonating frequency bands are observed at 2.02 GHz, 5.87 GHz and 11.19 GHz. The structure provides minimum return loss of −10.27 dB, −18.51 dB and −18.59 dB. The proposed design achieves a peak bandwidth of 3.94 GHz, and a maximum gain of 10.03 dBi, Various diversity parameters, including Total active reflection coefficient (TARC), Envelope Correlation Coefficient (ECC), mean effective gain (MEG), Diversity Gain (DG), and channel capacity loss (CCL), have been thoroughly analyzed. The measured and simulated outcomes are compared and analyzed. All performance indicators meet the allowed limits, demonstrating the suitability of the design for 5G, Wi-Fi and WLAN wireless communication applications.

Design and analysis the performance of triangular patch antenna for THz applications

Modern technology advancement requires a more extensive data rate to convey information more rapidly than ever. Improved bandwidth can satisfy the need for high-speed transmission demand. In order to achieve significantly increased bandwidth for a high data rate communication, the antenna design at the THz band is essential. The microstrip patch antenna is one of the most prominent antennas for THz band applications such future 5G communication systems and advanced wireless communication system. This paper proposed a triangular patch antenna for THz applications where FR4 is used at the substrate as an insulator and Graphene at the patch as a conductor. Moreover, we improve the performance of the proposed antenna by modifying the shape of the patch and ground (GND) layer. We modify the patch shape by cutting the corner edge of the triangular patch. Moreover, the GND layer is modified with horizontally partial ground. The size of the proposed antenna is set to 160×120 µm2. We analyze the performance of the proposed antenna using CST simulation software. Based on the simulation results, the proposed antenna with a modified patch and GND shape shows wide bandwidth of 1.27 THz and minimal return loss of -33.22 dB at a resonant frequency of 2.28 THz. Additionally, the gain and efficiency of the suggested antenna show good improvement. Therefore, the proposed triangular patch antenna with a modified patch and GND shape is expected to be suitable for high-speed THz applications.

Sickle-shaped high gain and low profile based four port MIMO antenna for 5G and aeronautical mobile communication

The construction of the four-port MIMO antenna in the form of a sickle is provided in the article. Initially, the single port element is designed and optimized. Next, a structure with two ports is created, and lastly, a design with four ports is completed. This process is repeated until the design is optimized. Three types of parametric analysis are considered, including variations in length, widths of sickle-shaped patches, and varying sizes of DGS. The frequency range of 2–8 GHz is used for structural investigation. The − 18.77 dB of return loss was observed at 3.825 GHz for a single-element structure. The optimized one-port structure provides a return loss of − 19.79 dB at 3.825 GHz. The port design offers a bandwidth of 0.71 GHz (3.515–4.225). The four-port design represents two bands that are observed at 3 GHz and 5.43 GHz. Both bands provide the return loss at respectively − 19.79 dB and − 20.53 dB with bandwidths of 1.375 GHz (2.14–3.515) and 0.25 GHz (5.335–5.585). The healthy isolation among both transmittance and reflectance response is achieved. The low-profile material was used to create the design that was presented. The article includes a comparison of the findings that were measured and those that were simulated. The four-port design that has been shown offers a total gain of 15.93 dB, a peak co-polar value of 5.46 dB, a minimum return loss of − 20.53 dB, a peak field distribution of 46.43 A/m and a maximum bandwidth of 1.375 GHz. The values for all diversity parameters like ECC are near zero, the Negative value of TARC, Near to zero MEG, DG is almost 10 dB, and a zero value of CCL is achieved. All diversity parameter performance is within the allowable range. The design is well suited for 5G and aeronautical mobile communication applications.

A 2 shape slot microstrip patch antenna for global positioning system satellite communication applications

In this paper, a compact two-shape slot microstrip antenna is proposed for global positioning system (GPS) satellite application. The proposed antenna is designed with FR 4 substrate with a height of 1.6 mm, a dielectric constant εr of 4.3 within a compact size 56 x 56 mm2 area. The design parameters are optimized to achieve good performance. At the optimum setting of design parameters, this antenna shows good characteristics to cover L1 band 1,575.42 MHz, ± 12 MHz frequency which is used for GPS satellites. At the 1,572 MHz resonance frequency, this antenna achieves a minimum return loss of -30 dB covering a frequency bandwidth of 50 MHz (1,550 MHz – 1,600 MHz) at -10 dB reference level which ensures 100% bandwidth coverage of the L1 band. Besides, the proposed antenna achieved a maximum gain of 8.3 dBi and a beam width of 1010 at -3 dB point. In terms of other performance, such as voltage standing wave ratio (VSWR), directivity, radiation pattern, the proposed antenna shows good performance for the application of GPS satellites.

An eye bolt shape slotted microstrip patch antenna design utilizing a substrate-integrated waveguide for 5G systems

Antenna design is usually done on FR4 substrates, since they have a dielectric constant of 4.4, and a loss tangent of 0.02. The proposed microstrip patch antenna operates at 28 GHz and incorporates substrate-integrated waveguides (SIW) in a 0.8 mm thick FR4 substrate into the design to increase bandwidth performance so that the 5G network can function reliably. In comparison with conventional patch antennas, substrate-integrated waveguides bear the advantage of being able to shift to a frequency of 29 GHz, therefore resulting in a more effective antenna. A slot of eyebolt shape has been added to the patch to increase antenna gain. The design was simulated with HFSS software, and it was able to attain a maximum bandwidth of 8 GHz (28%), a gain of 5.5 dB, and a minimal return loss of −38 dB. The VSWR of this antenna is 1.02, which indicates good impedance matching, and a high efficiency of 87% has been achieved as a result. This is a low-profile antenna that combines enhanced bandwidth with the ability to be mounted at the edge of a device, making it an ideal choice for the use of 5G technology to enable machine-to-machine communication.

Design and analysis of multiple beams phased array microstrip antenna for 5G applications

The paper presents a novel and compact antenna array design fed through a 3 dB BLC for producing phase shift in the array. Beam steering is an attractive design feature for avoiding obstacles in the path of the beam. It is achieved by switching the beam to another path by simply varying the phase shift between elements. The proposed structure exhibits resonance in the frequency having range of 27.6 GHz −29.6 GHz with a minimal return loss value of −45 dB for frequency applications of 28 GHz, which can be further employed for 5G frequency applications, there are two multiple beams observed, with main beam at theta equal to −35 degrees, the main beam shifts to +28 degrees by changing the feed port of the coupler. A stable gain of around 11.5 dB is obtained for the entire frequency range. The input phase has been varied for different elements in the array, and best results were obtained for a 90 degree phase difference, which required the use of a 3 dB BLC. Rogers RT Duroid 5880, having a dielectric of 2.2 and a 0.51 mm dielectric height, was used as a substrate for antenna fabrication. The simulations were performed on the CST Microwave studio and the measurements were done on VNA (Agilent N5247A).

Design of graphene-based multi-input multi-output antenna for 6G/IoT applications

In the future, 6G wireless communications will be integrated into various applications. It is expected that it will handle all Internet of Things services as well as satellite communications. Additionally, it is predicted to support machine learning (ML) and artificial intelligence (AI). So this work investigated four orthogonal ports graphene-based multiple-input and multiple-output (MIMO) antenna in the terahertz frequency regime. With wide-band (7.1-13) THz, minimum return loss close to -30 dB and a good isolation value. That was designed over silicon dioxide (Sio2) 100×100 substrate with a thickness of 10 µm and a maximum gain reaching 8.3 dB at 11 THz. By adjusting the provided DC voltage, the chemical potential of graphene can be tuned, which in turn allows for the MIMO antenna characteristics to be changed. Envelop correlation coefficient (ECC) and diversity gain (DG) were investigated for the presented design. In addition, these values were determined to assess compatibility and difficulties connected with communication over a short distance. The geometry of the MIMO antenna is adaptable to various applications in the THz band with highperformance requirements, such as sensing, scanning for security threats, biomedical applications, wireless communication systems with high speed built on the 6G standard, and the internet of things (IoT).