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In this paper the material characterization at sub-millimetre wave frequencies facility recently developed at the European Space Research and Technology Centre (ESA-ESTEC) to complement existing antenna ranges is presented. By means of a Quasi Optical test bench, transmission/reflection measurements from 50 to 500 GHz are performed. Complex material parameters are then calculated from transmission...
Reduction of human exposure to electromagnetic radiation generated by mobile phones terminals is a major concern both for equipment manufacturers and users. Reduced fares and technological development (antenna integration, energy consumption decrease, etc) led to an unprecedented increase of phone call duration with yet unknown consequences on human beings and especially on children. The authors identified...
In this work, we study for the first time the nonlinearity of AlN piezoelectric material subjected to high RF electric field (E). Nonlinear effects in BAW (Bulk Acoustic Wave) resonators are seen as a frequency shift and an amplitude variation at the resonance (fr) and anti-resonance (fa) frequencies. Moreover the coupling factor increases for high power measurements (high E). By model fittings, these...
In this paper, we present results of measurement S21 parameter for two special shielding materials in the 2,5-5 GHz frequency band. Measurements were carried out using well-known free-space transmission technique. Experimental set-up has been modified by adding an absorbing frame to reduce resonant and diffraction effects at specimen edges. Shielding effectiveness (SE) of two test materials depending...
A method using broadband acoustic holography has been put forward to determining the reflection coefficients at arbitrary angles of incidence and compared with mono-frequent acoustic holography. The selection principle about every parameter has been deduced by numerical experiments on an aluminum board. Under an average error level of 10%, the radius of holographic plane should be greater than two...
In this study, we propose an optimized NRUS measuring and data processing protocol dedicated to small bone samples specially designed to be used in a four-point bending mechanical fatigue test. Our goal was to assess the elastic and dissipative hysteretic nonlinear parameters repeatability with the proposed protocol using several classes of materials with weak, intermediate and high nonlinear properties...
Multiple modes excited in a single solidly-mounted ZnO bulk acoustic resonator would provide a multi-band resonator operating at non-harmonically-related frequencies in the GHz range. Ordinarily, separate devices with different electrode and reflector designs are needed to excite the thickness shear (TSM) and thickness-extensional (TE) bulk acoustic modes, each device optimized for a single mode....
A methodology to characterize the complex dielectric permittivity of low-loss materials at millimeter and submillimeter wavelengths, based on whispering gallery mode dielectric resonators, is presented, together with some illustrative results.
Spectroscopic images were obtained using a system combining a tunable continuous-wave terahertz laser with an InP-based Schottky barrier diode detector integrating a broadband log-periodic antenna. The distribution of polymorphic forms in pharmaceutical tablets was observed in obtained at images over 1 THz.
We discuss and verify experimentally the design of a 1-D planar periodic combline leaky-wave antenna that avoids the open-stopband effects as the beam is scanned through broadside.
The cylindrical cavity resonator method is presented to evaluate the complex relative permittivity of lossy materials. The loaded sample in the cavity is required to have the rotational symmetry but may have bulky and/or wide sample. To measure the sample at the specified frequency with high Q, movable dielectric supports with low permittivity and low loss are loaded in cavity. Theoretical basis of...
We proposed an application of the refractive polarizing Fourier Transform Spectrometer (r-FTS) to millimeter submillimeter wave multiband polarimetry. In this paper, the results of optical experiments in millimeter wavebands, aiming to verify the performance, will be reported.
We model and compare the uncertainties of the refractive index and the coefficient of absorption of materials in the far-infrared, determined from THz time-domain spectroscopy performed in reflection and in transmission. Our study is experimentally validated. We give rules to select the most appropriate experimental technique regarding studied samples.
The characterization of materials is one major task for systems which work e.g. in the field of quality or production control. One factor to analyze material volume information is the permittivity. The following paper describes a measurement method to determine and gives an overview about the measurement system. In addition first measurement results will be shown.
A two-contact photoconductive antenna has been experimentally found to be frequency-dependent and respond to the mixture of both polarization components of terahertz radiation. This effect leads to wrong polarization state measurement results. It may also result in a fake “absorption peak”.
We have developed a new measurement device called Dual Focus Flat Cavity (DFFC) that can measure the shielding effectiveness (SE) of a material up to a frequency of 33 GHz. SE depends on the measurement setup, and therefore, characteristics inherent to materials, such as sheet resistance, should be evaluated. In this study, we estimated the sheet resistance of a material by solving the inverse problem...
This report describes the decrease technique for the microwave exposure by which conductive cloth was inserted in the dress. The shield performance decreases fatally when the slit and the hole exist in conductive cloth usually. However, when the resistance material fringes the conductive clothes edge, it has been found to be able to avoid fatal deterioration of shield performance. The optimum fringing...
New magneto-dielectric material with improved electromagnetic properties in UHF band is manufactured. These electromagnetic properties, in particular the low levels of losses, show that this material could be useful to the design of miniaturized antennas in the VHF-UHF (300 MHz-700 MHz) range of frequency. This new material has been used to load a small coplanar slot antenna. Performances of the antenna...
Alumina Enhanced Thermal Barrier (AEBT-8) material is currently being considered as a potential radome material for phased array antennas that will be conformally mounted to the outer surface of NASA's Orion Crew Exploration Vehicle. Accordingly, there is a need to establish if the dielectric properties of the AEBT-8 material change as a function of temperature. In this paper we discuss the measurements...
In this work the dielectric response of three commonly used polymeric insulating materials, namely polyvinyl chloride (PVC), polytetrafluoroethylene (PTFE) and high-density polyethylene (HDPE), was measured after applying combined action of UV-radiation and condensation (humidity and heat) in an Accelerated Weathering Tester apparatus. Test samples were planar with a 2 mm thickness. For both aged...
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