- 标题
- 摘要
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- 实验方案
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A 230-GHz High-Power and Wideband Coupled Standing Wave VCO in 65-nm CMOS
摘要： This article presents a 230-GHz wideband harmonic voltage-controlled oscillator (VCO) with large output power based on a compact and low-loss structure of coupled standing wave oscillators. In order to boost the output power, oscillators are coupled together without adding extra passive loss to the circuit. Transistors with inductive drain impedances provide the necessary negative resistance to the oscillators while simultaneously acting as active variable capacitors for frequency tuning and generate the desired second-harmonic power through their nonlinearities. Transmission lines at the drains are responsible for creating the inductive impedance as well as coupling adjacent oscillators and routing and combining the output power. Therefore, the circuit has a compact structure that minimizes passive losses. A varactor-less frequency tuning scheme is used and allows for wideband operation without sacrificing the output power. In addition to oscillator coupling and minimizing the losses, the output power has been boosted by engineering the harmonic impedance that is seen by the transistors in the circuit. The prototype chip was implemented in a 65-nm CMOS process. The output power of the VCO covers 219–238 GHz frequency band (8.35% tuning range) and delivers 3.4-dBm maximum output power. The minimum measured phase noise is ?105.8 dBc/Hz (at 10-MHz offset) while consuming 195 mW from a 1.5-V supply.
关键词： standing wave,low-loss,THz,wideband,frequency tuning,Compact structure,millimeter-wave (mm-Wave),voltage-controlled oscillator (VCO),mm-wave/terahertz (THz) power generation,harmonic oscillator,varactor-less
更新于2025-09-12 10:27:22
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An advanced approach to control the electro-optical properties of LT-GaAs-based terahertz photoconductive antenna
摘要： This work reports on an advanced approach to the design of THz photoconductive antenna (PCA). The LT-GaAs thin films used for the PCA fabrication were synthesized by MBE method on GaAs (100) substrate by adjusting the As pressure, As/Ga fluxes ratio, growth/annealing temperatures and annealing time. These parameters crucially affect electro-optical properties of the PCA samples as evidenced by the THz radiation power and time-domain spectroscopy measurements. The annealing temperature of 670 °C was found to be optimal for constructing a PCA possessing high amplitude of the THz radiation over the spectral range up to 1 THz at the resonance of 0.1 THz. The comparison of this PCA with the reference ZnTe crystal reveals a 2-fold increase in THz power. Furthermore, this antenna attains a 1.5-, 3-, and 2-fold increase in THz power, photocurrent efficiency, and actuating dc BV, as compared with the commercial ZOMEGA antenna. These results pave the way towards the creation of highly efficient LT-GaAs-based PCAs.
关键词： THz-antenna,Terahertz (THz) radiation,Photoconductive antenna (PCA),Low temperature-grown gallium arsenide (LT-GaAs),THz-spectroscopy
更新于2025-09-11 14:15:04
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Wideband Rectangular Double-Ring Nanoribbon Graphene-Based Antenna for Terahertz Communications
摘要： A wideband nanoribbon graphene-based antenna with double rectangular rings for terahertz (THz) applications is presented. The wideband and efficient graphene-based antenna on physical parameters is developed in this paper. The antenna has a wide impedance bandwidth of 26% at the center frequency of 1 THz, minimum return loss equal to 24 dB and average radiation efficiency approximately equal to 44% is obtained. An average gain of 2.45 dB is achieved at the operational frequency band. The goal of this paper is to provide an antenna with capabilities of being wideband, efficient and re-configurable with a simple and single-layer structure for THz communication.
关键词： Double-ring antenna,wideband antenna,graphene,terahertz,THz,re-con?gurable,nanoribbon antenna
更新于2025-09-11 14:15:04
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[IEEE 2019 5th Conference on Knowledge Based Engineering and Innovation (KBEI) - Tehran, Iran (2019.2.28-2019.3.1)] 2019 5th Conference on Knowledge Based Engineering and Innovation (KBEI) - A Triple-Band THz Metamaterial Absorber Based on Symmetrical Split Rings
摘要： A simple pattern of a triple band terahertz (THz) absorber is presented. This absorber formed by only triple symmetrical split rings backed with a solid ground layer which is separated by a dielectric layer substrate. It is investigated that the presented absorber has three different absorption bands in which the average of the peaks is close to 96%. Results reveal that the absorption bandwidth of the presented design is insensitive to wave incident angle. In addition, in order to enhance the absorption peaks, a new method is introduced which is based on the difference of split rings thickness. Owing to the simple structure of the proposed absorber, the fabrication process can be quite easy. Therefore, the proposed THz absorber is able to perform in applications such as sensing, detection, and imaging.
关键词： split rings structure,metamaterial,triple band,terahertz (THz),absorber
更新于2025-09-11 14:15:04
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Modulation Mode Detection & Classification for in-Vivo Nano-Scale Communication Systems Operating in Terahertz Band
摘要： This work initiates the efforts to design an intelligent/cognitive nano receiver operating in Terahertz (THz) band. Specifically, we investigate two essential ingredients of an intelligent nano receiver—modulation mode detection (to differentiate between pulse based modulation and carrier based modulation), and modulation classification (to identify the exact modulation scheme in use). To implement modulation mode detection, we construct a binary hypothesis test in nano-receiver’s passband, and provide closed-form expressions for the two error probabilities. As for modulation classification, we aim to represent the received signal of interest by a Gaussian mixture model (GMM). This necessitates the explicit estimation of the THz channel impulse response, and its subsequent compensation (via deconvolution). We then learn the GMM parameters via Expectation-Maximization algorithm. We then do Gaussian approximation of each mixture density to compute symmetric Kullback-Leibler divergence in order to differentiate between various modulation schemes (i.e., M -ary phase shift keying, M -ary quadrature amplitude modulation). The simulation results on mode detection indicate that there exists a unique Pareto-optimal point (for both SNR and the decision threshold) where both error probabilities are minimized. The main takeaway message by the simulation results on modulation classification is that for a pre-specified probability of correct classification, higher SNR is required to correctly identify a higher order modulation scheme. On a broader note, this work should trigger the interest of the community in the design of intelligent/cognitive nano receivers (capable of performing various intelligent tasks, e.g., modulation prediction etc.).
关键词： nano-scale communication,Expectation-Maximization algorithm,Kullback-Leibler divergence,Gaussian mixture model (GMM),modulation classification,Terahertz (THz) band,modulation mode detection
更新于2025-09-09 09:28:46
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Effective Medium Model of Periodic Nanolayered Transparent Shields
摘要： An innovative effective medium model based on the transfer matrix method is proposed for the simulation of 1D-periodic subwavelength metal–dielectric laminated structures excited by TM- or TE-polarized plane wave with oblique incidence angles. The homogeneous medium of each period is characterized by TM or TE complex effective permeability and conductivity. The resulting effective single layer (ESL), having the same total thickness of the multilayer laminate, is represented by a transfer matrix given by the product of the transmission matrices of the periods composing the structure. Notice that this model allows the homogenization of n-layer periods, while the effective medium approximation method is formulated for only two-layer periods. The ESL is used to compute the transmission and reflection coefficients and the shielding effectiveness of 1D-periodic nanolayered transparent coatings made by alternating layers of silver, zinc oxide, or titanium dioxide films, in the frequency range from 100 MHz up to 10 THz. The propagating wave performances of the ESL are compared with the ones given by the rigorous multilayer model. Finally, two different screens made of transparent coatings over glass are proposed and analyzed.
关键词： 1D-periodic multilayer (ML) coating,Effective homogeneous model,terahertz (THz) shielding effectiveness
更新于2025-09-09 09:28:46
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[IEEE 2018 IEEE International Conference on Computational Electromagnetics (ICCEM) - Chengdu (2018.3.26-2018.3.28)] 2018 IEEE International Conference on Computational Electromagnetics (ICCEM) - Roughness Impact on the RCS of Simple Canonical Objects in the Terahertz Regime
摘要： The higher the frequency is, the greater the influence of the precision and the realism of the CAD models on electromagnetic (EM) scattering characteristics are. In the terahertz (THz) regime, surfaces of most objects can’t be taken as smooth according to Rayleigh criterion. The interaction of EM waves and the surface presents a coherent part in the specular direction and a scattering part in the other directions. Unfortunately, the roughness of surface can’t be represented by the CAD geometry. Based on statistics theory, the rough surface height profile is fully determined by the height probability density function (pdf) and its autocorrelation functions. Without loss of generality, the height pdf of surface is assumed to be Gaussian. Under the assumption, the random Gaussian rough is correspondingly generated. The original CAD surface geometry and the random Gaussian rough surface are superposed as the input of EM computation. To demonstrate the roughness impact on RCS, EM scattering characteristics of simple canonical objects such as plate and dihedral in the THz regime are investigated. Taking into account the statistical surface roughness, the ray-based high-frequency EM method, shooting and bouncing rays (SBR), is utilized to compute the RCS of the objects above in the THz regime. Furthermore, the inverse synthetic aperture radar (ISAR) images are also carried out via filtered back projection (FBP) method. The EM scattering characteristics of the objects above in the THz regime are analyzed. Great differences of the objects EM scattering characteristics between the smooth and rough ones are observed and discussed.
关键词： roughness,shooting and bouncing rays,terahertz (THz),canonical objects
更新于2025-09-04 15:30:14
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[Institution of Engineering and Technology 12th European Conference on Antennas and Propagation (EuCAP 2018) - London, UK (9-13 April 2018)] 12th European Conference on Antennas and Propagation (EuCAP 2018) - 140 GHz Linear to Circular Polarization Convertor Based on Modified Cross Slot Frequency Selective Surface with High Selectivity
摘要： A 140 GHz linear to circular polarization converter based on a frequency selective surface (FSS) with high selectivity is proposed and designed in this paper. The periodic element of the converter includes a square substrate integrated waveguide (SIW) cavity and two cross slots with stubs etched on the top and bottom conductor claddings of the cavity. Based on the SIW cavity, a transmission pole is provided to improve passband characteristics and sideband selectivity. Besides, this THz converter can be easily fabricated using normal PCB process instead of compacted and high-cost technologies.
关键词： high selectivity,frequency selective surface (FSS),circular polarization (CP),Terahertz (THz) technology,substrate integrated waveguide (SIW) cavity
更新于2025-09-04 15:30:14