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For spectrum analysis at freuqencies >67 GHz external harmonic mixers are used in combination with a spectrum analyzer. Operation fundamentals, image suppression and image free frequency range are discussed. Modern mixers with low conversion loss provide a high dynamic range, e.g. for measuerement of EIRP of radio links in the E band.
In this presentation, we experimentally demonstrate a broadband absorber in the terahertz (THz) spectral band. A thin silicon dioxide (SiO2) film is used as dielectric spacer. The combination of different sizes of Al squares gives rise to an absorption bandwidth over 200GHz with absorption magnitude of 90%.
The two spatiotemporally shaped, orthogonally polarized optical pulses undergoes difference-frequency mixing in nonlinear crystal. The phase matching condition of difference frequency mixing is theoretically investigated. Maximum coherent length and output power in ZnTe, GaAs, GaP, InP and CdTe crystals could be obtained with pump wavelengths at 800nm, 1350 nm, 1000 nm, 1200 nm and 1000 nm respectively.
A new metamaterial (MTM) for THz range applications is proposed. The unit cell consists of indium antimonide (InSb) and silicon (Si) single-layered fishnet MTM. The InSb-based MTM shows enhanced resonance in the THz band and can be efficiently tuned by changing doping level of the semiconductor.
An analytic model with different levels of cross-polarization for Gaussian feed is proposed to facilitate a general investigation of the cross-polarization in CATR's quiet zone. Simulation results based on GRASP are shown how different levels of cross-polarization of Gaussian feed affects the cross-polarization of the quiet zone in the proposed CATR.
The design of a 2-way power-combined amplifier module based on GaAs MMIC power amplifiers from Northrop Grumman is presented. The module incorporates WR-10 waveguide quadrature hybrids as power splitting/combining structures to achieve higher output power than a single amplifier-based module for driving Schottky diode-based frequency-multiplied terahertz sources.
This paper reports our simulation of the starting process of oscillation in a 42 GHz gyrotron using CST Particle Studio. The computer model of the gyrotron is setup using the similar parameters in Ref[1]. We have looked into the mode competition and building up of oscillation in this gyrotron's model. Also, we have investigated the influence of external magnetic field and azimuthal corrugation on...
Experimental results are presented of the first successful low-terahertz region operation of a pseudospark-driven backward wave oscillator (BWO) in the frequency range of 140 GHz to 220 GHz. The experiment agrees well with 3D particle-in-cell numerical simulations.
In this work, two kinds of phenylthiourea compounds are used as model systems to study the inter-molecular interactions between aromatic rings and the dynamics of the methyl internal rotation which falls into the terahertz region. Experimental and theoretical studies are utilized to identify low-frequency vibrational modes.
The double corrugated waveguide is an effective slow wave structure for realizing THz vacuum electron devices. Collisions of electrons of the beam, flowing between the corrugations, with the metal walls could determine a relevant thermal effect. This paper describes a preliminary thermal analysis of the structure by ANSYS simulator.
Heating systems are of outstanding relevance in magnetically confined plasmas in tokamak devices. They provide the tools to reach and sustain burning conditions. DEMO, and the future reactor require higher frequency for ECH. Therefore, high power (≥1MW) RF sources with output frequency in the 200–300 GHz range would be necessary.
A figure of the research effort on Terahertz radiation on a worldwide scale is given by a statistical analysis of papers presented at the IRMMW-THz Conference during the past few years. This series of conferences is the oldest and largest forum specifically devoted to the field of Infrared, Millimeter, and Terahertz Waves.
Design of the staggered double vane slow wave structure (SWS) for two bands of traveling wave tube (TWT) amplifier, one for Ka-band and another one for W-band, has been presented in this paper. The high-frequency characteristics of this kind of structure were calculated by the HFSS eigenmode solver. And particle-in-cell method was carried out to investigate the amplification performance of this structure...
In this paper, TeraView TPS3000 is adopted to evaluate wheat seed status and structures. A set of imaging tests have been done. By using the dataprocess software, seed structures can be revealed clearly. We conclude that wheat seeds' status and structures can be identified by terahertz imaging effectively and non-destructively.
This paper presents the design of an electron gun employable in THz vacuum tubes. A Multiphysics (MP) approach has been used in the electron gun design in order to study the effect of the multiple influencing factors such as mechanical stress or thermal expansion togheter with charged particle in electrostatic and magnetostatic fields.
The latest developments and experimental results a W-band gyro-TWA with a helically corrugated waveguide and a cusp electron gun are presented. The cusp gun generated a 40 keV, 1.5 A axis-encircling electron beam. The gyro-TWA was predicted to output 5 kW with a 3 dB frequency bandwidth of 90–100 GHz.
We recently showed (Savini 2012) the use of stacked graded photolithographic capacitive metal-mesh structures on polypropylene substrates to produce a thin flat Wood lens working in a wide (90%) bandwidth. Here an additional impedance-matched layer is designed to improve the original lens efficiency in a wide band around the central frequency of operation.
A cryogenic based primary noise standard specifically suited for THz applications is described. Key features which offer improved THz performance are described. The standard consists of a common cryogenic vessel with replaceable waveguide antenna assemblies and a computer controlled interface.
In a structure of nano-scale metal film with dielectric medium loading, the surface plasmon polaritons (SPPs) excited by a uniformly moving electron beam bunch can be transformed into Cherenkov radiation with intensity enhancement in the medium. Based on the mechanism, Surface Polariton Cherenkov Light Source (SPCLS) is proposed and explored.
Though hyperspectral imaging (HSI, or hypercube) has been applied in a wide range of applications, it suffers from massive volume of data for efficient data storage and transmission. Herein improved 3D discrete cosine transform (DCT) is proposed with good results yielded. Experiments on several datasets have validated the efficacy of our approach.
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