The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
This contribution presents the design of a dual polarized leaky lens antenna coupled to a Kinetic Inductance Detector (KID) in order to enable a broadband THz detector for future space applications. The designed antenna presents high aperture efficiency and clean symmetric patterns.
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...
In this paper, with the help of a two-dimensional (2D) particle-in-cell (PIC) code, a simulation of Smith-Purcell (SP) radiation from the dielectric loaded grating is performed in the terahertz regime. The results show that the SP radiation frequency is in good agreement with the theoretical curve. Comparing with the general grating, the usage of dielectric loaded grating enhances the evanescent wave,...
A simple method is presented to characterize the dielectric probe for the near-field beam scanning in mm-wave domain. It is shown that the probe spatial-response can be modeled by Gaussian functions and then directly used in the convolution process to determine the actual measured field. Therefore, the complicated classic deconvolution operation can be replaced by an easy comprehensive analytical...
In previous work, we have studied thermal and behavioral effects and the detection of termites by millimeter waves. Motivated by the intriguing possibilities of millimeter wave — cellular, and higher level, biological interactions, we have investigated the design of an acupuncture-like needle for efficient delivery of millimeter waves through the skin. Contrary to conventional knowledge, a bare conductor...
We demonstrate imaging with a single-shot THz Time Domain spectrometer for the rapid, but precise location and characterization of defects in an adhesive bond.
Structures based on a periodic surface lattice (PSL) of planar geometry have been studied. It is shown that volume and surface fields can couple to form a cavity eigenmode, demonstrating the potential for novel mm-wave sources when combined in appropriate configurations with an electron beam.
Terahertz digital off-axis holography has been demonstrated as a non-destructive imaging tool for three-dimensional (3D) printed structures. Digital holographic reconstructions from two structures were used to measure the imager's modulation transfer function and to show that terahertz digital holography can provide submillimeter resolution images of visually opaque printed structures and map their...
In the summer of 2011, I was awarded a Consolidator Grant by the European Research Council titled “Advanced Antenna Architectures for THz Sensing Systems (AAATSI)”. The grant lasts 5 years and is aimed at solving the “antenna dispersion problem”: i.e. improving the efficiency x Bandwidth product in THz antennas. To achieve this goal an enhanced Fourier Optics methodology is being developed and three...
In an effort to develop compact millimeter and THz wave radiation power sources, two types of traveling wave amplification concept with multi-beam have been studied using Pierce small signal analysis and particle-in-cell (PIC) simulation. Our prior work includes theoretical and numerical assessment on performance of the aluminum-nitride (AlN)-loaded multi-beam structure, indicating that the TM31-mode...
The higher transmission through tissues of long wavelength light motivates the development of fluorescent proteins with excitation shifted to the red. However red fluorescent proteins (RFPs) are more susceptible to photobleaching than their shorter wavelength counterparts. In particular RFPs are more susceptible to photobleaching [1]. A possible reason for this is a decrease in the structural stability...
This paper presents the analysis and design of the pill box input and output windows for THz traveling-wave tube (TWT) amplifier. Both the theoretical mechanism and simulation results are analyzed. The simulation results clearly show a pass band 14 GHz of the window as desired frequency. The results can provide a foundation on the fabricating of THz TWT amplifier.
We report the first investigation of single Titanium Dioxide (TiO2) sub-wavelength size (20–30μm) spheres and ellipsoids using THz near-field microscopy. The Mie resonances are observed in individual particles allowing characterization of the resonance line-width and its dependence on the particle dimensions and shape.
Experiments on study of surface waves launched with a monochromatic terahertz source are described. We compare characteristics of the surface waves at the gold samples of different curvature covered with thin dielectric layers. Transmission of SEWs across surface impedance boundaries and air gaps is also examined.
We investigate through numerical simulation the coupling properties of a novel, AC-coupled, contact-free probe. The new probe couples radiation from a CPW-embedded device-under-test via polarization current, which is then transformed to conduction current in the probe and down-converted in frequency to baseband by an optically-pumped photomixer. Numerous simulations have been realized in order to...
Negative-type liquid crystal material, which has an inverse dielectric anisotropy for the low frequency, is introduced on a microstripline for modulating its dielectric constant with low driving voltage and low power consumption. Since the molecular orientation response for the driving voltage is inverted in comparison with positive-type LC materials, the transmission MMW phase magnitude decreases...
A systematic study of strained SrTiO3/DyScO3 heterostructures was performed using time-domain terahertz spectroscopy in the temperature range from 20 to 294 K. Interdigitated electrodes deposited on top of the structures allowed probing of the terahertz response upon an applied electric field. We explored a possibility to increase the total thickness of SrTiO3 layers while maintaining the epitaxial...
We propose a design of small-core multiple-layer Bragg waveguide for guiding the THz signal by TE01 mode, which is composed of alternating un-doped silicon (high refractive index) and high-density polyethylene (low refractive index). The group velocity of the THz wave traveling inside this small-core waveguide slows down to below 0.5c, while the propagation loss is less than 0.3 dB per centimeter...
This paper reports the design, fabrication, and characterization of a suite of dielectric probes for near-field and evanescent microfluidic sensing applications. Four different probe designs are studied. These structures are made from cylindrical alumina dielectric rods, and were integrated with microfluidic channels. Mixtures of two different solvents were used to characterize the probes. The sensitivity...
We use subwavelength metal rigs to control THz transmission through a planar dielectric waveguide. In this case magnetic field has maximal projection on the current loops. Transmission enhancement is observed in a narrow frequency band for a particular orientation of rings gaps and field polarization.
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.