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Considering the frequency dispersion of the complex dielectric permittivity for metals, the accurate radar cross section (RCS) of a copper sphere is given from microwave to the optical frequency. By investigate the effects on the RCS caused by the dispersion of metals, we show that polished copper sphere can be treated as perfectly electrical conductor (PEC) for the RCS prediction at terahertz frequencies.
A three dimensional (3D) linear theoretical modal for a sine waveguide sheet beam travelling wave tube is developed based on the field matching method. The dispersion curve for a 0.22THz sine waveguide slow wave structure is given. The effects of the beam parameters on the beam-wave interaction are discussed.
This paper presents a liquid crystal (LC) phase shifter design for 250 GHz combining micro-milling and micro-fabrication — bearing in mind the potential for combining several phase shifters into one array. Simulation was carried out in order to find estimates for insertion loss and matching. Furthermore, the maximum differential phase shift is calculated. The presented structure is designed with mechanical...
Polystyrene composites with 0.25 wt. % loading of oriented multiwall carbon nanotubes (MWCNTs) have been produced by stretching method. The composites showed anisotropy of transmission of millimeter wave radiation depending on sample orientation relative to the polarization of electromagnetic wave.
Frequency dependence of the complex dielectric constant at 2 % and 4 % moisture content for 4 wood species in longitudinal and transverse fiber directions were measured using a free space method. Anisotropic properties of wood, notably manifested at 0.1–0.5 THz are marked.
Evaluation of the effect of the protective case of an antenna on wave propagation by measurement is difficult when the wave length is 1 mm such as for a frequency of 300 GHz. Thus, evaluation based on simulation is required and electric parameters such as the complex relative permittivity are needed for the simulation. In this study, we first constructed a system for measuring complex relative permittivity...
A compact quasioptical setup is designed and optimized for material characterization in the frequency range 50 GHz to 500 GHz. The S-parameters are measured with a commercial Vector Network Analyzer (VNA) together with its mm/sub-mm frequency extenders. A simple practical calibration process is used to determine the diffracted waves on the material surface. A new method is proposed to extract the...
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...
A THz TDS study of permittivity and conductivity properties of new variant of Yttria-stabilized-Zirconia (YSZ) produced using tape-cast method is reported. This study extends the frequency coverage of some of the previously published work. We find a general agreement with published results but the frequency gap in the mm-wave range needs to be measured more carefully before final conclusions on the...
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