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Equivalent-Circuit Model with Retarded Electromagnetic Coupling for Meta-Atoms of Wired Metallic Spheres
摘要： This paper describes the equivalent-circuit model of a metamaterial composed of conducting spheres and wires. This model involves electromagnetic coupling between the conductors, with retardation. The lumped-parameter equivalent circuit, which imports retardation to the electromagnetic coupling, is developed in this paper from Maxwell’s equation. Using the equivalent-circuit model, we clarify the relationship between the retardation and radiation loss; we theoretically demonstrate that the electromagnetic retardation in the near-field represents the radiation loss of the meta-atom in the far-field. Furthermore, this paper focuses on the retarded electromagnetic coupling between two meta-atoms; we estimate the changes in the resonant frequencies and the losses due to the distance between the two coupled meta-atoms. It is established that the dependence characteristics are significantly affected by electromagnetic retardation.
关键词： meta-atom,equivalent-circuit model,metamaterial,electromagnetic coupling,radiation,retardation
更新于2025-09-23 15:22:29
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[IEEE 2018 IEEE MTT-S International Conference on Numerical Electromagnetic and Multiphysics Modeling and Optimization (NEMO) - Reykjavik, Iceland (2018.8.8-2018.8.10)] 2018 IEEE MTT-S International Conference on Numerical Electromagnetic and Multiphysics Modeling and Optimization (NEMO) - Low-Cost Simulation-Driven Design of Broadband Rectifiers for Ambient RF Energy Harvesting
摘要： A steady growth of ambient RF energy density associated with a rapid increase of the number of broadcasting devices stimulates the research on broadband harvesting circuits. Such circuits can be used as energy sources for low-power sensors or Internet-of-Things devices. On the other hand, dedicated design techniques for rectifiers are lacking which results in poor performance of existing circuits. Also, their design cost is high because it involves hybrid electromagnetic (EM) and harmonic balance (HB) simulations. In this work, we propose a novel design procedure for low-cost design of broadband rectifiers. The core component of the approach is a novel equivalent-circuit-based low-fidelity model which does not involve harmonic balance (HB) simulations. The model consists of a matching circuit loaded with the RF-to-DC converter block represented using the S-parameter matrix. The latter is obtained from a single HB simulation of the converter circuit. Inaccuracy of the model is reduced using appropriate correction techniques. At the first stage of the design process, the proposed model is optimized for minimization of the in-band reflection. At the second stage, a hybrid HB-EM-based tuning oriented towards maximization of the structure efficiency is carried out. The proposed approach is demonstrated using a novel broadband rectifier operating within 0.5 GHz to 3.5 GHz band. Numerical cost of the method is 80% lower compared to direct EM-HB- based optimization of the rectifier circuit.
关键词： broadband rectifiers,constrained optimization,simulation-driven design,surrogate-based optimization,equivalent circuit model
更新于2025-09-23 15:21:21
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[IEEE 2019 International Conference on Signal Processing and Communication (ICSC) - NOIDA, India (2019.3.7-2019.3.9)] 2019 International Conference on Signal Processing and Communication (ICSC) - Design and Implementation of Photonic Crystal Vertical Cavity Surface Emitting Laser
摘要： An injection-locked magnetron with an external oscillator was investigated to obtain the parameters of the equivalent circuit model. The magnetron was locked over the ratio of the input power to output power of ?26 dB and had the resonance characteristics of a parallel LCR circuit model. Increasing the input power caused the anti-resonance frequency to become the original frequency of the magnetron; the range of the locking frequency was wider because of the lower Q value. The phase noise of the locked magnetron of ?70 dBc at a 40-kHz offset was improved in comparison with an unlocked magnetron. The results show that an injection-locked magnetron with an external oscillator has great potential for obtaining a high power output.
关键词： frequency locking,injection-locked magnetron,Equivalent circuit model of magnetron
更新于2025-09-23 15:21:01
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Tunable Terahertz Graphene-Based Absorber Design Method Based on a Circuit Model Approach
摘要： In this paper, a simple, fast, and novel method for designing a tunable terahertz absorber with arbitrary central frequency and desired fractional bandwidth is presented. The proposed absorber consists of a single layer periodic array of graphene ribbons (PAGRs), placed a quarter wavelength from a metallic ground, separated by a dielectric material. An analytical circuit model of the terahertz absorber is used to obtain analytical expressions for the input impedance of the proposed device. Then, a simple expression for determining the value of capacitance and the resonance conditions of the RLC circuit is used to achieve a terahertz absorber with arbitrary central frequency and desired fractional bandwidth. The proposed method is applicable for the design of both narrowband and broadband absorbers, with only one layer of graphene ribbons. Also, the presented method is applicable for designing ultra-wideband absorbers using multiple layered PAGRs. Full-wave numerical simulation is performed to verify the accuracy and validity of the presented method. Excellent performance of the proposed method in terms of computation time and memory resource and providing the desired terahertz absorber characteristics shows that our method is promising as a design approach for sensing, imaging and ?ltering applications.
关键词： circuit model,graphene,Terahertz absorber,transmission line method,tunable bandwidth
更新于2025-09-23 15:21:01
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A Stretchable Metamaterial Absorber with Deformation Compensation Design at Microwave Frequencies
摘要： A stretchable microwave metamaterial absorber with specific pattern design is proposed and fabricated in this paper to improve the stability of microwave absorption for deformation. Compensation mechanism is revealed by the electrical current loop for resonance absorption excitation in equivalent circuit model. The proposed metamaterial absorber with slotted cross pattern is compared with the conventional cross pattern absorber. A stretchable silver conductive ink validates the silk screen printing of resistive patterns on flexible polydimethylsiloxane (PDMS) substrate and hence realizes the stretching experiments. In a 25% stretch, the resonant frequency of the compensated absorber shifts only 0.5% for TM polarization, comparing to the 8% shifting of the conventional structure.
关键词： Stretchable,compensation mechanism,metamaterial absorber,resistive patterns,equivalent circuit model
更新于2025-09-23 15:21:01
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Analytical Methods of Equivalent Circuit Model and Transmission Matrix for a Plasmonic Switch with Sensing Capability in Near-Infrared Region
摘要： In this paper, the simultaneous switching and sensing capabilities of a compact plasmonic structure based on a conventional rectangular hole in a silver film are proposed and investigated. The proposed structure has ultrahigh sensitivity up to 3000 nm/RIU and high figure of merit of 170 RIU?1. Also, the simulation results show the potential of the presented refractive index sensor to detect malaria infection, cancer cells, bacillus bacteria, and solution of glucose in water. Simultaneously, by changing the incident lightwave polarization, the structure behaves like a plasmonic switch, which has high extinction ratios of 15.81, 31.20, and 25.03 dB at three telecommunication wavelengths of 850, 1310, and 1550 nm, respectively. The ultrafast response time of 20 fs is achieved for the wideband application of the switching capability at the wavelength range of 1056 to 1765 nm. Moreover, the equivalent circuit model and transmission (ABCD) matrix methods are derived to validate the simulated results. Simple design, good agreement between the numerical and analytical results, biomedical applications, ultrahigh sensitivity, and ultrafast performance of the proposed structure help this idea to open up paths for design and implementation of other multi-application plasmonic devices in near-infrared region. To the best of our knowledge, the mentioned analytical methods have not been studied former at near-infrared wavelengths. Therefore, the achievements could pave the way for verifying the simulation results of plasmonic nanostructures in future investigations.
关键词： Near-infrared,Switch,Circuit model,Transmission matrix,Sensor,Biomedical,Polarization-multiplexing,Plasmonic
更新于2025-09-23 15:19:57
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Continuous-variable quantum teleportation with vacuum-entangled Rindler modes
摘要： We consider a continuous-variable quantum teleportation protocol between a uniformly accelerated sender in the right Rindler wedge, a conformal receiver restricted to the future light cone, and an inertial observer in the Minkowski vacuum. Using a nonperturbative quantum circuit model, the accelerated observer interacts unitarily with the Rindler modes of the field, thereby accessing entanglement of the vacuum as a resource. We find that a Rindler-displaced Minkowski vacuum state prepared and teleported by the accelerated observer appears mixed according to the inertial observer, despite a reduction of the quadrature variances below classical limits. This is a surprising result, since the same state transmitted directly from the accelerated observer appears as a pure coherent state to the inertial observer. The decoherence of the state is caused by an interplay of opposing effects as the acceleration increases: the reduction of vacuum noise in the output state for a stronger entanglement resource, constrained by the amplification of thermal noise due to the presence of Unruh radiation.
关键词： quantum circuit model,Rindler modes,Unruh effect,continuous-variable quantum teleportation,vacuum entanglement
更新于2025-09-23 15:19:57
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DEVELOPMENT OF AN EQUIVALENT CIRCUIT MODEL OF A FINITE GROUND COPLANAR WAVEGUIDE INTERCONNECT IN MIS SYSTEM FOR ULTRA-BROADBAND MONOLITHIC ICS
摘要： An equivalent circuit model of a ?nite ground plane coplanar waveguide (FGCPW) interconnect in a metal-insulator-semiconductor (MIS) system for an ultra-broadband monolithic IC is proposed and illustrated. An e?ective substrate considering Maxwell-Wagner Polarization is suggested and demonstrated. The method of modeling the weak skin e?ect of the conductor is presented. The accuracy of the equivalent circuit model is evaluated. This proposed FGCPW interconnect equivalent circuit model enables a quick and e?cient time domain simulation to estimate the time delay and bandwidth of ultra-broadband ICs.
关键词： FGCPW interconnect,MIS system,equivalent circuit model,weak skin effect,Maxwell-Wagner Polarization,ultra-broadband monolithic IC
更新于2025-09-23 15:19:57
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A ternary nanocomposites of graphene / TiO <sub/>2</sub> / polypyrrole for energy storage applications
摘要： Designing a new electrode active materials including graphene and nanomaterials such as Titanium dioxide (TiO2) with polypyrrole have important for supercapacitor devices. In this work, we present a new ternary nanocomposite for using reduced graphene oxide (rGO), TiO2 and polypyrrole (rGO/TiO2/PPy) for supercapacitors. rGO/TiO2/PPy nanocomposites were characterized by the analysis of Fourier transform infrared-attenuated transmission reflectance (FTIR-ATR), Raman spectroscopy, and scanning electron microscopy-energy dispersion X-ray analysis (SEM-EDX). Electrochemical tests were taken by galvanostatic charge/discharge (GCD), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) studies. We have obtained the highest specific capacitance of Csp D 431.23 F/g for [rGO]o/[Py]o D 1/1 at 10 mV/s. A ternary rGO/TiO2/PPy nanocomposite has higher Csp values than Csp D 122.12 F/g at 10 mV/s for rGO/PPy, Csp D 93.17 F/g at 4 mV/s for rGO and Csp D 45.16 F/g at 4 mV/s for GO. A high energy density was obtained as E D 2.03 Wh/kg and power density of P D 18.3 kW/kg for rGO/TiO2/PPy nanocomposite at 1000 mV/s. rGO/TiO2/PPy nanocomposite had a relatively high Coulombic efficiency, as well as a retention of ?100% of its original capacitance for [rGO]o/[Py]o D 1/1 after 1000 cycles. A novel synthesized rGO/TiO2/PPy nanocomposite may be used for supercapacitor devices due to its good electrochemical performances.
关键词： energy density,reduced graphene oxide,circuit model,TiO2,supercapacitor,polypyrrole
更新于2025-09-23 15:19:57
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A novel analytical method for designing a multi-band, polarization-insensitive and wide angle graphene-based THz absorber
摘要： In this paper, we propose a simple and analytical method to design a multi-band tunable graphene-based absorber using circuit model. The presented paper provides a flowchart and equations to design a multi-band absorber which tremendously simplifies the design procedure of a multi-band absorber. This paper only investigates the disk shape graphene-based absorber, but we believe the proposed method is extendable to all presented shapes of graphene which previously designers provided with a circuit model. To verify the accuracy of the presented method; we have designed several multi-band absorbers and used Full-wave numerical modeling of the structure to approve our method. Also, this paper studies the reliability of our proposed model by investigating the fabrication sensitivity of the structure. Lastly, this paper investigates to see how a multi-band absorption spectra behave, in case there are any errors during the fabrication phase. The designed absorbers have potential applications in various fields of active THz metamaterials, tunable filters, and sensors. The graphene-based disk-shaped absorber has the advantage of polarization insensitivity, wide-angle absorption and ease of implementation due to its simple shape. Another advantage of using graphene in the absorber structure is that with the availability of changing the Fermi energy level, it is possible to tune the absorption frequency of the multi-band absorbers.
关键词： Circuit model,Absorber,Graphene Terahertz,Tunable bandwidth,Transmission line method
更新于2025-09-19 17:15:36