Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 66 for “"L-Band"”.
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Design of an L Band Radar Sensor
… of a SAR transceiver, as a prototype L band sensor, to be used in a software defined radar system. This examination includes the evaluation, testing and recommissioning the available hardware. Tests on various subsystems which make up the sensor are carried out and described in detail.
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L-band RFI measurement system simulation and investigation
… a dwell time of 2μS duration over a large 1 MHz bandwidth in the 960 -1400 MHz band (L-band). The reason for this short dwell time is to capture and characterize pulsed interference from radars and Distance Measuring Equipment (DME) in this band. This kind of interference is expected, potentially …
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Design and Analysis of L-Band Reconfigurable Liquid-Metal Alloy Antennas
Efficient reconfigurable antennas are highly sought after in all communication applications for the ability to reduce space cost while maintaining the ability to control the frequency, gain, and polarization. The ability to control these parameters allows a single antenna to maximize its …
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Adaptation of an unused paraboloidal reflector for L-band drift scan observations
… reflector, with a focal ratio of 0.34, in an L-band radiometer system targeting observations of the neutral hydrogen 21cm line. A coaxial cavity feed horn was implemented using cost-effective manufacturing techniques. The horn is comprised of sheet metal sections and standard aluminum pipe. The …
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System design of the MeerKAT L - band 3D radar for monitoring near earth objects
This thesis investigates the current knowledge of small space debris (diameter less than 10 cm) and potentially hazardous asteroids (PHA) by the use of radar systems. It clearly identifies the challenges involved in detecting and tracking of small space debris and PHAs. The most significant …
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Design and implementation of a dual polarised L-band parabolic dish antenna for NeXtRAD
Research into multi-static, multi-band networked radar has led to the development of the NeXtRAD radar system. This dissertation will investigate the design and implementation of a dual polarised L-Band prime focus dish antenna with a centre frequency of 1.3 GHz and a HPBW of 10° in the azimuth …
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Hillslope-scale soil moisture estimation with a physically-based ecohydrology model and L-band microwave remote sensing observations from space
… model estimates with noisy active and passive L-band microwave observations. Uncertainty in the modeled soil moisture state is estimated through Monte Carlo simulations with an existing spatially distributed ecohydrology model. Application of the EnKF to estimate hillslope-scale soil moisture in …
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Part~I: Determination of Quadrupole Couplings via L-Band, B(0) // B(1) EPR. Part~II: Surface Interactions of Perylene Adsorbed on Oxide Powders
Nuclei in the environment (matrix) of the radicals were also probed by ENDOR spectroscopy. Depending on the nature of the sample and experimental conditions, signals could be detected from $\sp1$H, $\sp2$D, and $\sp{27}$Al. The source and behavior of these signals are investigated with special …
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Multifrequency Scintillation in the Polar Caps
… measures amplitude and phase signals in the L-band. Through these measurements we can calculate the scintillation indexes, S_4 and sigma_phi to gain insight into the plasma density structures the scintillation originated from. In this Thesis, the processes of detrending and processing VHF …
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Tidal Wetland Inundation and Vegetation Phenology from Space: A Synthesis of Approaches for Characterizing Ecological Status and Inundation Dynamics in Tidal Wetlands with Remote Sensing Observations
… approach utilized multitemporal Sentinel-1 C-band SAR imagery. The same decision tree classification was utilized to map non-persistent emergent vegetation, an indicator of tidal freshwater wetlands, with greater than 93% accuracy.</p> <p>Chapter 4 seeks to assess tidal marsh inundation …
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A Roughness Correction for Aquarius Ocean Brightness Temperature Using the CONAE MicroWave Radiometer
… global sea surface salinity (SSS), using an L-band radiometer that measures ocean brightness temperature (Tb). The application of L-band radiometry to retrieve SSS is a difficult task, and therefore, precise Tb corrections are necessary to obtain accurate measurements. One of the major error …
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The Design of an Anti-Aliasing Filter for the Next Generation Digitiser
… signals produced by celestial sources at UHF-Band, L-Band, S-Band and X-Band frequencies. The first phase of the construction included the design, development and integration of the UHF-Band, L-Band and S-band Receivers, whilst the X-band design has been superseded by the incorporation of the …
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Soil parameter retrieval under vegetation cover using SAR polarimetry
… SAR acquisitions at a longer wavelength (L-band, lambda=23cm). In this thesis, the penetration capabilities of L-band are combined with newly developed (multi-angular) polarimetric decomposition techniques to separate the different scattering contributions, which are occurring in vegetation …
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A study of bistatic radar and the development of an independent bistatic radar receiver
… radar and also describes an experimental L-Band bistatic radar receiver which was built at the University of Cape Town. In a bistatic radar the transmitter and receiver are separated by an amount which is comparable to the distance to the targets which are being displayed. The separation of …
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A study of satellite contamination for single dish Hi intensity mapping with MeerKAT
… In this work, we attempt to use the higher L-Band frequency data (1300 - 1500 MHz) and understand the foreground behavior at higher frequencies. We use a foreground removal pipeline used for previous works with the lower L-band frequencies and make additions to it which allow us to identify …
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Design and implementation of L and X-band filters for the NeXtRAD front end
… research radar called NeXtRAD to suppress out of band transmitted and received signals. NeXtRAD is a multistatic pulse-Doppler radar system, developed at the University of Cape Town (UCT) in collaboration with the University College London (UCL). It has been designed to operate in two frequency …
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Multi-Layered Dual-Band Dual-Polarized Reflectarray Design Toward Rim-Located Reconfigurabable Reflectarrays for Interference Mitigation in Reflector Antennas
… interference in the important L- and X-band frequencies which are crucial for astronomical observations. This thesis introduces reflectarray design which can serve as a basis for an interference mitigation solution for radio telescopes. In the envisioned application, When the …
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Evaluation of diode-based non-linear transmission lines as microwave sources in compact pulsed power systems
… HPM sources by demonstrating the generation of L-band spectral content in MW+ pulses. Nonlinear transmission lines composed of saturable magnetic materials and nonlinear dielectrics are a standard choice for high power rf sources, but are lacking in some combination of compactness, power …
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Design and Implementation of an RF front end for the NeXtRAD radar system
… benefits to be derived from a multistatic, dual-band (X- and L-band), polarimetric radar architecture, particularly within dense clutter environments such as the maritime environment. By examining the high-level system requirements and objectives, requirement specifications for the RF front end …
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