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 26 for “"Reflector antennas"”.
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Tolerance analysis of synthesized dual-reflector antennas
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1993.
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Adaptive Pattern Modeling for Large Reflector Antennas
… of large axisymmetric paraboloidal focus-fed reflector antenna systems. The intended application of these methods is to improve the performance of time-domain interference canceling (TDC) in radio astronomy. The first method yields a closed-form expression for the antenna pattern with …
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Modification of Large Reflector Antennas for Low Frequency Operation
Modifications of large reflector antennas, such that their observing capabilities are enhanced in the range of about 10-500~MHz without affecting operation of the pre-existing higher-frequency systems, are addressed in this dissertation. The major contributions of this dissertation can be divided …
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Beam scanning offset Cassegrain reflector antennas by subreflector movement
… for the mission was a wide scanning, high gain reflector antenna system for use in radiometric remote sensing from geostationary orbit. This work describes research conducted at Virginia Tech into techniques for beam scanning offset Cassegrain reflector antennas by subreflector translation and …
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Analysis of scanning in dual offset reflector antennas and the bifocal system
Thesis (Elec. E.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science; and, (B.S.)--Massachusetts Institute of Technology, Dept. of Mathematics, 1982.
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Analysis and design of linear-to-circular polarising reflector antennas exploiting periodic metallodielectric arrays
… design linear-to-circular polarising reflector antennas comprising doubly periodic metallodielectric arrays. These type of structures, used in conjunction with subreflectors, has risen as a promising solution to reduce the number of reflectors in multi-beam antennas in single-feed-per beam …
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A synthesis procedure for array feeds to improve radiation performance of large distorted reflector antennas
Surface errors on parabolic reflector antennas degrade the overall performance of the antenna. They cause amplitude and phase errors in the aperture field which lower the gain, raise the side lobes, and fill in the nulls. These are major problems in large ->space reflector antenna systems. F or …
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Synthesis of Offset Dual Reflector Antennas Transforming a Given Feed Illumination Pattern Into a Specified Aperture Distribution
… through two reflections by an offset dual reflector system is investigated using the concepts of geometrical optics. A numerically rigorous solution for the reflector surfaces is developed. The solution gives an exact aperture phase distribution and an aperture amplitude distribution …
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Synthesis of dual offset Gregorian reflector antennas with very low cross polarization under practical constraints for mass production
… characteristics of axisymmetric and offset reflector antennas. Single and dual reflector configurations are considered. Cross polarization (XPOL) and beam squint are examined in detail. Although many of the phenomena are known, they are interpreted and explained in new ways and presented in …
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Multi-Layered Dual-Band Dual-Polarized Reflectarray Design Toward Rim-Located Reconfigurabable Reflectarrays for Interference Mitigation in Reflector Antennas
… small potion of the rim of the paraboloidal main reflector, its presence does not significantly effect the main lobe peak gain. Since Iridium and Starlink are the target mega-constellations, the reflectarray must be dual band. To cover the operational bandwidths of these constellations, the target …
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Printed log-periodic feeds for radar applications
… is detected using narrow beam width directive antennas (i.e. reflector antennas). The ability to discern about the nature and size of the target depends on the radar resolution which is related to the bandwidth and to the electrical size of the antenna. The physical principles of radar are …
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Selected Reflector Antenna Studies
… studies some of the current research topics in reflector antennas. The topics dicussed are reflector surface distortion, compensation and detection; reflector near-field analysis; and reflector antenna surface shaping. Each chapter of the thesis covers one topic and is self-contained. The most …
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Effects of random surface errors on the performance of paraboloidal reflectors
… to study the radiation patterns of paraboloidal reflector antennas whose surfaces are subjected to random errors with the emphasis on using an accurate representation of the statistics of the random surface errors. An ensemble of Gaussian random surfaces is created to be used with the Monte Carlo …
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Efficient Techniques for Near-Field Computation and Subreflector Analysis
… the method for both planar aperture and reflector antennas are given.
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Antenna systems research
… been grouped into 7 categories: - Log periodic antennas, - Antenna performance measurement techniques, - Spacecraft Antenna Systems, - Satcom Terminal Antennas, - Transmission lines and baluns, - High Radar Cross Section Reflectors for Spaceborne Radar Calibration, - Miscellaneous Antenna …
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Standalone Antenna Demonstration System
… used in present-day applications (embedded and reflector antennas), in addition to structural barriers encountered in typical operating environments, are used to define wireless system performance. Students gain insight on radiating structure and orientation effects on antenna system …
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Log-Periodic Loop Antennas
The Log-Periodic Loop Antenna with Ground Reflector (LPLA-GR) is investigated as a new type of antenna, which provides wide bandwidth, broad beamwidth, and high gain. This antenna has smaller transverse dimensions (by a factor of 2/pi) than a log-periodic dipole antenna with comparable radiation …
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The Development of a Small Scale Radio Astronomy Image Synthesis Array for Research in Radio Frequency Interference Mitigation
… imaging arrays are composed of many parabolic reflector antennas. These antennas are designed to be extremely sensitive to detect faint emissions from astronomical sources. Unfortunately, this also makes them susceptible to radio frequency interference (RFI) from man made sources such as …
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Characteristics of different focusing antennas in the near field region
Focusing antennas are of interest in many application including microwave wireless power transmission, remote (non-contact) sensing, and medical applications. Different kinds of antennas such as array antennas, reflector antennas and Fresnel zone plate (FZP) antennas have been used for these …
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