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The design of dielectric wedge-scanned millimeter wave lens antennas with measured results is presented. The diffractive lens antenna (DLA) is treated; it incorporates a lens that transforms the radiation pattern of a scalar feedhorn. A schematic diagram of a zoned dielectric wedge-scanned DLA with Fresnel spherical surface is presented. An efficient device for scanning the beam produced by a DLA...
The "Abbe barrier" may be completely broken by curvilinear (conical) 3D diffractive lenses with unique 3D super resolution (∼0.4λ0 and ∼0.8λ0 for transverse and axial respectively), but in contrast to the flat diffractive optic the curvilinear 3D diffractive conical optic allow to overcome 3D Abbe barrier with focal distance F more than F>2λ.
Layered metasurfaces made of gold loop antennas are proposed for beam engineering at telecom band. Any transmitted amplitude or phase profile is designable by modifying the loop configuration cell by cell and layer by layer. Applications of 3D beam scanning and focusing are studied numerically and high efficiency of > 80% is achieved thanks to the low ohmic loss and the perfect impedance match...
In this paper, the design, fabrication and characterization of a 3D printed Luneburg lens antenna working at Ka and Q band are proposed. Gradient index control of the lens is based on the mixing ratio of air voids and polymer. The effective dielectric constant of the unit cell was estimated using effective medium theory and extracted from full-wave finite-element simulation results. The diameter of...
This article describes a semi-coaxial through glass via(TGV) interposer structure for high frequency three dimensional(3D) system applications. In order to overcome impedance mismatch in high frequency transition, a semi-coaxial structure is designed. The glass is 200 μm thick and the via's diameter is 50 μm. Re-distribution layer (RDL) line to TGV transition structure is designed and simulated to...
It has been experimentally shown that in the near field of single diffractive lens with subwavelength focal distance F≤λ without of the immersion medium a resolution of 0.3–0.4λ were obtained. The "Abbe barrier" can be completely broken by such diffractive lenses with unique 3D super resolution. Also it was experimentally shown the focal spot in the high numerical aperture diffractive lenses...
We demonstrate a technique of fabricating freestanding all-metal two-dimensional (2D) and three-dimensional (3D) terahertz metamaterials through injection molding of gallium, a metal that melts at temperatures slightly above room temperature. To obtain free-standing metamaterials, two polydimethylsiloxance (PDMS) molds are created using conventional soft lithography, reversibly bonded through van...
We present sub-millimeter wave transceiver modules intended for imaging radar applications. In particular a novel circuit architecture that operates in homodyne FMCW radar mode will be highlighted [1], and the trade-offs between performance and circuit complexity will be discussed. The transceiver units are based on monolithically integrated Schottky diodes fabricated on 3 μm thick membranes. Radar...
Time domain THz spectroscopy and 3D imaging are used for non-destructive analyses of modern pottery which was made using ancient and traditional technology. Our study demonstrates that the internal structure of this of Pre-Columbian civilizations Mochica type pottery can be revealed with the help of X-Ray images used as references.
We present a series of aspherical lenses and diffraction gratings 3D printed for use as optical components in terahertz spectroscopy systems. Commercially available plastics for 3D printing (VisyJet Crystal, Acrylonitrile Butadiene Styrene (ABS) Plastic and acrylic based polymers) have also been characterized via Terahertz Time Domain Spectroscopy (TDS) and two-color wave photomixing. In addition,...
The extended interaction oscillator (EIO) is regarded as a novel type of high power terahertz (THz) source, which has promising application prospects in radar, medical imaging etc. Up to now, CPI and other institutes have developed many types of EIO. For satisfying with the application request, the EIO with operation frequency exceeding 300GHz is designed and studied with three-dimensional particle-in-cell...
A portable THz imaging system for the study of wall paintings is currently under construction in the framework of the THz-ARTE project. The device design and operating principle will be presented together with preliminary results on test samples.
We experimentally demonstrate single-mode broadband THz propagation in hollow core waveguides fabricated with a 3D printer with metallic inclusions. The measurement data obtained from the Terahertz (THz) Time Domain spectroscopy experiments show low loss guidance and low dispersion characteristics, and these are in very good agreement with the results obtained from numerical simulations of the investigated...
In this paper we present a new processing sequence to perform (i) tomographic reconstruction, (ii) automated segmentation, (iii) component labelling and (iv) accurate measurements of an object from its 3D THz acquisition. This sequence, implemented in a new 3D THz imaging software2, is validated through the analysis of several samples.
Terahertz (THz) tomography is a recent imaging technique allowing 3D inspection of opaque objects. In this paper, we investigate a dual-energy experimental setup and a THz tomographic reconstruction algorithm based on dual-energy measurements. We discuss how this dual-energy approach is able to extract physical properties of acquired samples in addition to the 3D reconstruction from acquisitions measured...
Numerical FDTD and PiC simulations demonstrate the successful electron wave interaction in a Cherenkov maser utilizing a cylindrical 2D PSL as a mode selective cavity. Optimization of this structure's physical properties results in the design of a cavity with 16 longitudinal periods of 1.6 mm length, 7 azimuthal variations and an unperturbed inner radius of 4 mm. In numerical simulations this design...
Cold test results of a G-band sheet beam backward wave oscillator (BWO) with a double grating waveguide, fabricated by wire cutting and a 3D printing technique, are presented in this paper. The dispersion curve and S-parameters of the BWO slow wave circuit and Bragg reflector were measured and the results compared to the numerical modelling and analytical theory.
The extended interaction oscillator (EIO) is regarded as a novel type of high power terahertz (THz) source, which has promising applications prospects in military radar, medical imaging and wireless communications, etc. For being satisfied with the widely applications, a THz EIO operation at G-band is designed and studied with three-dimensional particle-in-cell simulation at IECAS. To improve the...
Beyond ITER, a future nuclear fusion demonstration power plant (DEMO) demands gyrotron frequencies above 200 GHz and gyrotron efficiencies of higher than 60 %. The unit power must well exceed 1 MW. Fast frequency tunability in steps of 2–3 GHz (in a few seconds) using broadband or tunable CVD-diamond windows is required. Beside these fundamental requirements, slow frequency tunability (in a few minutes)...
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