نتایج جستجو برای: Radar wave absorption
تعداد نتایج: 379710 فیلتر نتایج به سال:
in this study, absorption of high frequency radio waves in the ionospheric plasma have beeninvestigated. the wave equation was obtained in terms of ionospheric parameters. the numerical values ofthe absorption have been calculated for 4 mhz, 4.5 mhz and 5 mhz waves. the necessary parameters forcalculation have been obtained using an international reference ionosphere (iri) model. the altitudina...
in this study, the effects of oleothermal modification on physical and mechanical peroperties of fir wood (abeis sp.) blocks were examined. at first, some blocks of fir wood with 5 × 20 × 120 cm dimensions were prepared. the blocks were treated in soybean oil. the effects of 3 factors such as treatments temperature (180and 200 °c), holding time (12 and 15 h) and initial moisture content of wood...
In this paper, a novel shore-based S-band microwave Doppler coherent wave radar (Microwave Ocean Remote SEnsor (MORSE)) is designed to improve wave measurements. Marine radars, which operate in the X band, have been widely used for ocean monitoring because of their low cost, small size and flexibility. However, because of the non-coherent measurements and strong absorption of X-band radio waves...
This theoretical study examines the characteristics of a surface wave driven plasma monopole antenna using finite difference time domain method (FDTD) as well as commercial full wave simulator. The results show that the full wave simulator can be considered as an acceptable tool in simulation of a plasma antenna. Input impedance, radiation pattern, gain, efficiency and radar cross section of pl...
Ocean wind and wave parameters can be measured by in-situ sensors such as anemometers and buoys. Since the 1980s, X-band marine radar has evolved as one of the remote sensing instruments for such purposes since its sea surface images contain considerable wind and wave information. The maturity and accuracy of X-band marine radar wind and wave measurements have already enabled relevant commercia...
[1] The technique for extracting wave period and wave direction from radar backscattering intensity is well developed, but the determination of spectral density or wave height is hindered by the complex nature of the modulation transfer function. In contrast to backscattering intensity, the Doppler signal of a coherent radar is originated from the radial velocity of the scattering objects. Its ...
[1] We compare Arecibo dual-polarization radar image data for Venus to Magellan images and emissivity data to investigate the physical properties of volcanic deposits. Radar waves can easily penetrate smooth mantling layers such as ash, aeolian and craterderived deposits. If a circularly polarized radar wave refracts into a surface that is smooth at wavelength scales, the vertical component of ...
Operational wave data assimilation at ECMWF started with ERS-1 radar altimeter wave heights on 15 August 1993. This had a significant impact on the wave model analysis and forecast. The impact of wave data assimilation based on the ECMWF experience is presented. This includes the impact of assimilation of ERS radar altimeter and synthetic aperture radar and ENVISAT radar altimeter-2 wave data. ...
Mitsubishi Electric Corporation has developed a millimeter-wave radar for automotive application. Monolithic microwave integrated circuits (MMICs), developed specifically for this application by Mitsubishi Electric, are used for the radio-frequency (RF) module to obtain outstanding radar performance. This millimeter-wave radar incorporates a signal-processing unit in the radar head, resulting i...
The proposed theorem in this paper is indicative of a kind of duality in the propagation of waves in the dual media of and in the spherical structures. Independent of wave frequency, the number of layers, their thickness, and the type of polarization, this theorem holds true in case of any change in any of these conditions. Theorem: Consider a plane wave incident on a multilayered spheric...
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