Spelling suggestions: "subject:"millimetrewave"" "subject:"millimeterwaves""
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Radiowave propagation modelling of vertical characteristics of rainstorms for high elevation angle slant path communication systems at millimetre wavelengthsDominguez, Javier Bandera January 2000 (has links)
No description available.
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Improvements to the modelling of radiowave propagation at millimetre wavelengths : in-depth studies are reported on resonance phenomena in the scattering of spherical ice particles, extinction and backscattering properties of clouds and on the absorption and dispersion spectra of atmospheric gasesPapatsoris, Anastassios Dimitriou January 1993 (has links)
Various physical mechanisms that affect radiowave propagation at millimetre wavelengths are considered. Current modelling weaknesses are highlighted and new improved models or more appropriate modelling approaches are suggested. Interference and resonance phenomena in the scattering of spherical ice and water particles are reviewed. The long standing problem of the numerous resonances observed in the scattering diagrams of dielectric spheres is answered. The spatial structure and the physical characteristics of non-precipitable ice and water clouds are reviewed. Extinction and back scattering calculations for a wide variety of cloud models over the entire millimetre frequency spectrum are given. Multiple scattering and the effects of super-large drops in clouds are also dealt with. The potential of a spaceborne instrument in deducing information about the vertical structure of various cloud types is examined. Attenuation and reflectivity profiles resulting from various cloud types are calculated for a nadir pointing fixed beam millimetre wave radar operating at 94 GHz. The physics and application of the equation of radiative transfer to millimetre wave propagation in the earth's atmosphere are given and also is the solution of this equation for a typical millimetre wave remote sensing application. The theory of gaseous absorption at millimetre wavelengths is presented and an improved modelling approach is proposed for the calculation of the absorption and dispersion spectra of atmospheric gases. The effects of trace gases on communication systems operating at high altitudes are for the first time reported. Finally the use of the 60 GHz oxygen absorption band for top-side air traffic control/navigation and broadband transmission purposes is studied.
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Hot electron bolometer sensors for millimetre-wave and terahertz wave detectionNortheast, David Bernard 03 1900 (has links)
Thesis (MScEng (Electrical and Electronic Engineering))--Univerity of Stellenbosch, 2011. / ENGLISH ABSTRACT: The design and simulation of hot electron bolometer sensors for the detection
of millimeter and terahertz wave radiation is presented. These devices can be
used for the formation of images or for spectroscopy in these frequency ranges.
Many molecules resonate and have absorption spectra over these ranges, allowing
for the identi cation, non-destructively and at a distance, of the constitution
of many di erent materials. The penetrating ability of the radiation
makes mm-wave and THz wave detectors ideal for security imaging. The design
and simulation of these devices predicts performance as mixers and as
interferometers. Manufacturing processes used while fabricating these thin
lm devices are outlined and experimental results are reported. / AFRIKAANSE OPSOMMING: Hierdie tesis bespreek die ontwerp en simulasie van warm-elektron bolometers
vir die waarneming van millimetergolf- en terahertz-straling. Sodanige
toestelle kan in bogenoemde frekwensiebereike gebruik word vir beeldvorming
of spektroskopie. Aangesien heelwat molekules binne hierdie bande resoneer,
kan die samestelling van 'n verskeidenheid materiale oor 'n afstand en op
'n nie-vernietigende wyse gedenti seer word. Die deurdringingsvermo van
millimetergolf- en terahertz-straling maak sulke detektors ideaal vir beeldvorming
in veiligheidstoepassings. Met die ontwerp en simulasie van hierdie
toestelle word gewys wat hul werkverrigting as mengers en interferometers kan
wees. Die prosesse wat gebruik is om hierdie dun lmtoestelle mee te vervaardig
word ook bespreek en eksperimentele resultate word aangebied.
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Improvements to the modelling of radiowave propagation at millimetre wavelengths. In-depth studies are reported on resonance phenomena in the scattering of spherical ice particles, extinction and backscattering properties of clouds and on the absorption and dispersion spectra of atmospheric gases.Papatsoris, Anastassios Dimitriou January 1993 (has links)
Various physical mechanisms that affect radiowave propagation at millimetre
wavelengths are considered. Current modelling weaknesses are highlighted and new
improved models or more appropriate modelling approaches are suggested.
Interference and resonance phenomena in the scattering of spherical ice and water
particles are reviewed. The long standing problem of the numerous resonances
observed in the scattering diagrams of dielectric spheres is answered.
The spatial structure and the physical characteristics of non-precipitable ice and water
clouds are reviewed. Extinction and back scattering calculations for a wide variety of
cloud models over the entire millimetre frequency spectrum are given. Multiple
scattering and the effects of super-large drops in clouds are also dealt with. The
potential of a spaceborne instrument in deducing information about the vertical
structure of various cloud types is examined. Attenuation and reflectivity profiles
resulting from various cloud types are calculated for a nadir pointing fixed beam
millimetre wave radar operating at 94 GHz.
The physics and application of the equation of radiative transfer to millimetre wave
propagation in the earth's atmosphere are given and also is the solution of this
equation for a typical millimetre wave remote sensing application. The theory of
gaseous absorption at millimetre wavelengths is presented and an improved modelling
approach is proposed for the calculation of the absorption and dispersion spectra of
atmospheric gases. The effects of trace gases on communication systems operating at
high altitudes are for the first time reported.
Finally the use of the 60 GHz oxygen absorption band for top-side air traffic
control/navigation and broadband transmission purposes is studied.
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