Dielectric constant and layer-thickness interpretation of helicopter-borne short-pulse radar waveforms reflected from wet and dry river-ice sheets

1991 ◽  
Vol 29 (5) ◽  
pp. 768-777 ◽  
Author(s):  
S.A. Arcone
Keyword(s):  
Dielectric Constant ◽  
Layer Thickness ◽  
Short Pulse ◽  
Ice Sheets ◽  
River Ice ◽  
Pulse Radar ◽  
Radar Waveforms

Investigation of Dead Layer Thickness in SrRuO3/Ba0.5Sr0.5TiO3/Au Thin Film Capacitors

2000 ◽  
Vol 655 ◽  
Author(s):  
L. J. Sinnamon ◽  
R. M. Bowman ◽  
J. M. Gregg
Keyword(s):  
Thin Film ◽  
Dielectric Constant ◽  
Layer Thickness ◽  
Perovskite Phase ◽  
Frequency Dispersion ◽  
Dead Layer ◽  
Parameter Ratio ◽  
Thin Film Capacitors ◽  
Dead Layer Thickness ◽  
The Dead

AbstractThin film capacitors with barium strontium titanate (BST) dielectric layers of 7.5 to 950 nm were fabricated by Pulsed Laser Deposition. XRD and EDX analyses confirmed a strongly oriented BST cubic perovskite phase with the desired cation stoichiometry. Room temperature frequency dispersion (ε100 kHz / ε100 Hz) for all capacitors was greater than 0.75. Absolute values for the dielectric constant were slightly lower than expected. This was attributed to the use of Au top electrodes since the same sample showed up to a threefold increase in dielectric constant when Pt was used in place of Au. Dielectric constant as a function of thicknesses greater than 70 nm, was fitted using the series capacitor model. The large interfacial parameter ratio di / εi of 0.40 ± 0.05 nm implied a significant dead-layer component within the capacitor structure. Modelled consideration of the dielectric behaviour for BST films, whose total thickness was below that of the dead layer, predicted anomalies in the plots of d/ ε against d at the dead layer thickness. For the SRO/BST/Au system studied, no anomaly was observed. Therefore, either (i) 7.5 nm is an upper limit for the total dead layer thickness in this system, or (ii) dielectric collapse is not associated with a distinct interfacial dead layer, and is instead due to a through-film effect.

scholarly journals Airborne River-Ice Thickness Profiling with Helicopter-Borne UHF Short-Pulse Radar

1987 ◽  
Vol 33 (115) ◽  
pp. 330-340 ◽  
Author(s):  
Steven A Arcone ◽  
Allan J Delaney
Keyword(s):  
Short Pulse ◽  
Hanging Wall ◽  
Open Water ◽  
High Water ◽  
High Water Content ◽  
Ice Thickness ◽  
Frazil Ice ◽  
Pulse Radar ◽  
Detailed Surface ◽  
Ice Conditions

AbstractThe ice-thickness profiling performance of a helicopter-mounted short-pulse radar operating at approximate center frequencies of 600 and 900 MHz was assessed. The antenna packages were mounted 1.2 m off the skid of a small helicopter whose speed and altitude were varied from about 1.8 to 9 m/s and 3 to 12 m. Clutter from the helicopter offered minimal interference with the ice data. Data were acquired in Alaska over lakes (as a proving exercise) and two rivers, whose conditions varied from open water to over 1.5 m of solid ice with numerous frazil-ice formations. The most readily interpretable data were acquired when the ice or snow surface was smooth. Detailed surface investigations on the Tanana River revealed good correlations of echo delay with solid ice depth, but an insensitivity to frazil-ice depth due to its high water content. On the Yukon River, coinciding temporally coherent surface and bottom reflections were associated with solid ice and smooth surfaces. All cases of incoherent surface returns (scatter) occurred over ice rubble. Rough-surface scattering was always followed by the appearance of bottom scattering but, in many cases, including a hanging-wall formation of solid frazil ice, bottom scattering occurred beneath coherent, smooth-surface reflections. Areas of incoherent bottom scattering investigated by drilling revealed highly variable ice conditions, including frazil ice. The minimum ice thickness that could be resolved from the raw data was about 0.2 m with the 600 MHz antenna and less than 0.15 m with the 900 MHz antenna.

scholarly journals Stratigraphic continuity in 400MHz short-pulse radar profiles of firn in West Antarctica

2004 ◽  
Vol 39 ◽  
pp. 195-200 ◽  
Author(s):  
Steven A. Arcone ◽  
Vandy B. Spikes ◽  
Gordon S. Hamilton ◽  
Paul A. Mayewski
Keyword(s):  
Short Pulse ◽  
Accumulation Rate ◽  
High Density ◽  
Thin Layers ◽  
East Antarctica ◽  
Relative Amplitude ◽  
Accumulation Rates ◽  
West Antarctica ◽  
Constructive Interference ◽  
Pulse Radar

AbstractWe track dated firn horizons within 400 MHz short-pulse radar profiles to find the continuous extent over which they can be used as historical benchmarks to study past accumulation rates in West Antarctica. The 30–40cm pulse resolution compares with the accumulation rates of most areas. We tracked a particular set that varied from 30 to 90 m in depth over a distance of 600 km. The main limitations to continuity are fading at depth, pinching associated with accumulation rate differences within hills and valleys, and artificial fading caused by stacking along dips. The latter two may be overcome through multi-kilometer distances by matching the relative amplitude and spacing of several close horizons, along with their pulse forms and phases. Modeling of reflections from thin layers suggests that the – 37 to – 50 dB range of reflectivity and the pulse waveforms we observed are caused by the numerous thin ice layers observed in core stratigraphy. Constructive interference between reflections from these close, high-density layers can explain the maintenance of reflective strength throughout the depth of the firn despite the effects of compaction. The continuity suggests that these layers formed throughout West Antarctica and possibly into East Antarctica as well.

scholarly journals Phase structure of radar stratigraphic horizons within Antarctic firn

2005 ◽  
Vol 41 ◽  
pp. 10-16 ◽  
Author(s):  
Steven A. Arcone ◽  
Vandy B. Spikes ◽  
Gordon S. Hamilton
Keyword(s):  
Phase Structure ◽  
Short Pulse ◽  
Double Layers ◽  
Accumulation Rates ◽  
West Antarctica ◽  
Antarctic Plateau ◽  
Pulse Radar ◽  
The Standard Model ◽  
Radar Resolution ◽  
The Antarctic

AbstractWe have recorded reflection profiles of firn through large areas of West Antarctica and part of the East Antarctic plateau using 400MHz short-pulse radar. The locations show accumulation rates that vary from well above to well below the vertical radar resolution. Most reflection horizons have extensive lateral continuity, and are composed of distinctive wavelets with a consistent phase polarity sequence within their successive half-cycles. We modeled these waveforms, and conclude that they arise from thin, double layers of ice over hoar, which is consistent with the standard model of firn stratification. In addition, we conclude that ice/hoar layers are extensive throughout West Antarctica and also present (although more sparsely) beneath the Antarctic Plateau.

scholarly journals Отражение света от слоя гиперболического метаматериала

2019 ◽  
Vol 127 (12) ◽  
pp. 954
Author(s):  
Н.С. Петров ◽  
С.Н. Курилкина ◽  
А.Б. Зимин ◽  
В.Н. Белый
Keyword(s):  
Dielectric Constant ◽  
Reflection Coefficient ◽  
Layer Thickness ◽  
Optical Axis ◽  
Extraordinary Wave ◽  
Angle Of Incidence ◽  
Absorbing Medium ◽  
Hyperbolic Metamaterial ◽  
Maximum Value ◽  
Elliptically Polarized

In this paper, we study the features of reflection of a plane elliptically polarized electromagnetic wave falling from an isotropic non-absorbing medium on a layer of hyperbolic metamaterial (HMM) the optical axis of which is parallel to the interface and the diagonal values ​​of the dielectric constant are less than the dielectric constant of an isotropic medium. It is shown that changing the values of the angle of incidence and the angle between the plane of incidence and the optical axis of the HMM one can realize different regimes of refrection: when ordinary ( or extraodinary) wave or both waves decay from the interface. Meanwhile, in the latter case, for some values ​​of the angles the decaying can be nonexponential. For these three cases, numerical calculations of the reflection coefficient from the ITO / Ag nanostructure layer are performed. When the polarization of the incident wave varies, the energetic reflection coefficient changes from minimum to maximum values which depend on the layer thickness. Unlike usual anisotropic media, in all cases the maximum value of the reflection coefficient tends to unity with increasing the layer thickness. When the amplitude of the ordinary or extraordinary wave does not decrease from the interface, the minimum reflection coefficient periodically vanishes with increasing layer thickness due to the interference. In the case when both waves decay, and under some conditions the incidence is not exponential, the minimum reflection coefficient vanishes at a certain layer thickness, and then tends to unity.

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