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 20 for “"boresight"”.
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Antenna boresight calibration using optimal estimation techniques
… azimuth misalignment of the antenna boresight with respect to the IMU is a significant contributor to motion compensation error. Currently, an awkward to perform, laser based antenna boresight calibration procedure is employed. This thesis investigates an alternative approach in which …
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Microwave Radiometer (MWR) Evaluation of Multi-Beam Satellite Antenna Boresight Pointing Using Land-Water Crossings, for the Aquarius/SAC-D Mission
This research concerns the CONAE Microwave Radiometer (MWR), on board the Aquarius/SAC-D platform. MWR's main purpose is to provide measurements that are simultaneous and spatially collocated with those of NASA's Aquarius radiometer/scatterometer. For this reason, knowledge of the MWR antenna beam …
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Airborne protected military satellite communications : analysis of open-loop pointing and closed-loop tracking with noisy platform attitude information
… antenna aperture size and GPS/INS unit for on-boresight, but not for off-boresight. With signal-to-noise ratios averaged over 100 hops and pointing biases less than or equal to 0.5 the half-power beamwidth, the step-tracking algorithm reduces the pointing error to within 0.1 the half-power …
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An optimized dual-polarized quad-ridges horn antenna with pyramidal sidewalls
… pattern of the antenna and large dips in the boresight gain. The performance of the quad-ridged horn antenna with pyramidal sidewalls is improved by separating the antenna into the transition and flared horn sections, and optimizing these sections individually. It is shown that a transition …
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Development of Integrated "Chip-Scale" Active Antennas for Wireless Applications
… (no PA) antenna indicates a gain of -12.7dB on boresight at 5.64 GHz, consistent with the antenna size reduction. The measurement of one active antenna (50 Ω system) shows a gain of -4.3dB on boresight at 5.80 GHz. The other version of active antenna (22.5 Ω system) shows a gain of −2.9 dBi on …
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Accuracy Improvement of Terrestrial Mobile Lidar System in Engineering Surveys
… both of tie points and tie features. Lastly, the boresight angles of a terrestrial LiDAR system was preliminarily calibrated by using the planar and/or line features of two scans acquired during consecutive runs in opposite driving directions at the post-processing stage proposed by Keller et al. …
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Modelling and resolving of the ambiguous angle of arrival measurements of the SANAE IV SuperDARN Radar
… below 33ᵒ in elevation when observing along boresight. This dissertation models a subcomponent of this phenomenon and develops an entirely separate pulsed-Doppler radar system on an FPGA platform known as the Red Pitaya. Operating parameters are specifically chosen to be consistent with the …
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Radar tracking system development
… keeping targets centered along the antenna boresight. Over three years, a new Seeker Computer was built to replace an old system constrained by obsolete hardware. The redevelopment project was a team effort and this thesis presents a systems-level analysis of the design process, the new …
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Mutual Coupling Reduction Techniques for Multi-band Base Station Antennas
… with the HB excitation, resulting in significant boresight radiation attenuation in the upper part of the HB operating band. A Fabry-Perot cavity antenna (FPCA) operating in the second resonance mode (N=1) is proposed to improve this attenuation through increasing the boresight directivity. Upon …
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Development of resource-constrained sensors and actuators for in-space satellite docking and servicing
… precision relative sensor designed to enable boresight visual docking. The measurements from this optical camera are applied to a nonlinear estimator to provide the highly accurate sensing necessary for docking. Finally, a free-flying robotic arm is examined and modeled as an experimental …
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Incoherent scatter modeling of Jicamarca radar spectra
… and the deviation angle of the radar boresight direction from the plane perpendicular to the geomagnetic field, the so-called magnetic aspect angle. While the extension of the model to the multi-ion case is straightforward, the discrete nature of the numerical electron ACF library …
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A Study of Indoor Ultra-wideband Propagation Measurement and Characterization
… radiated signals by TEM horn antennas along off-boresight directions are studied experimentally. Furthermore, pulse distortions resulting from propagation through dispersive walls are demonstrated by simulation. The roles of receive-transmit antennas in a UWB link are examined, and the …
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The Spiro-Helical Antenna
… the number of turns is 10, a gain of 11-14 dB, a boresight axial ratio of less than 3 dB, and a half-power beamwidth of about 40 degrees are achieved over a 30% bandwidth. The side-lobe level for most cases examined is better than 10 dB below the main beam. A unique advantage of this antenna is …
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Geração de pulsos radar na faixa de frequências de micro-ondas
… em relação à antena (∅), e do desvio de boresight da direção da máxima irradiação da antena (µ). Além disso, propôs-se um esquemático em bloco do circuito equivalente e sua implementação no HFSS. A equação que foi desenvolvida foi usada na modelagem do atenuador variável presente no …
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Concept Demonstrator for MeerKAT Operation from 14.5 to 20 GHz
… better than 15 dB in the operational band and boresight gain of 12 dB. The measured E- and H-plane cross-polarization for the antenna is lower than -40 dB. The measured edge taper at the halfsubtended angle of the sub-reflector is between -11.8 dB and -13.2 dB. The front-end receiver was …
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The Effects of Atomic Oxygen on Patch Antenna Performance and Lifetime
… Microwave Lab at Cal Poly was used to measure boresight gain and radiation pattern in the E-plane and H-plane. From the testing in the anechoic chamber it was determined that there was no apparent difference in the patch antenna’s gain and radiation pattern before and after AO exposure. By …
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Electronic scan weather radar: scan strategy and signal processing for volume targets
… data quality degradation occurs at far off boresight directions. The effective range for the bias correction methods is suggested by using radar simulation. The pulsing scheme used in PAWR requires a new ground clutter filtering method. The filter is designed to work with a signal covariance …
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Stealth technologies based on thin microwave FSS absorbers
… the antennas from the host vehicle removes the boresight null which occurs when the antenna is placed λ/2 above the CubeSat, and the forward hemisphere radiation pattern is shown to be very similar to the antenna in free-space.<br/><br/>This work also reports the use of resistively loaded FSS …
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Development of Efficient Techniques for the Analysis and Design of Antennas in Dual-Reflectarray Configuration
… ability to scan the beam over small angles about boresight. Two possible architectures for a Ku-band antenna are also described based on a dual planar reflectarray configuration that provides electronic beam scanning in a limited angular range. In the first architecture, the beam scanning is …
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An On-orbit Calibration Procedure for Spaceborne Microwave Radiometers Using Special Spacecraft Attitude Maneuvers
This dissertation revisits, develops, and documents methods that can be used to calibrate spaceborne microwave radiometers once in orbit. The on-orbit calibration methods discussed within this dissertation can provide accurate and early results by utilizing Calibration Attitude Maneuvers (CAM), …