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Full-Text Articles in Engineering
System Identification Of An On Orbit Spacecraft's Antenna Dynamics, Christopher M. Sylvester
System Identification Of An On Orbit Spacecraft's Antenna Dynamics, Christopher M. Sylvester
Theses and Dissertations
As a result of previous efforts [Pachter, Barba, 2007] a tight control loop was designed to meet performance specifications while minimizing the feedback control system’s gains of a spacecraft mounted flexible antenna. Emphasis is now shifted to on orbit system identification of the antenna dynamics in order to increase nominal plant knowledge, estimate plant uncertainty bounds, as well as determine the disturbance band. Non-parametric system identification is undertaken. Knowledge of the plant dynamics along with the corresponding uncertainty bounds will provide for the design of a control system which meets the specifications (tracking and disturbance rejection) while at the same …
Design And Optimization Of Broadband High Impedance Ground Planes (Higp) For Surface Mount Antennas, Murat Dogrul
Design And Optimization Of Broadband High Impedance Ground Planes (Higp) For Surface Mount Antennas, Murat Dogrul
Theses and Dissertations
Gain and bandwidth metrics of broad-band low-profile antennas severely deteriorate when they are placed conformally onto the conductive skins of air, sea, and ground platforms. This detrimental effect is primarily due to out-of-phase reflections from the conductive body interfering with the antenna’s self radiation. Furthermore, lateral waves launched by the antenna couple into the thin substrate placed between the antenna and the platform, giving rise to surface waves resulting in significant diffraction from the edges of the substrate. To remedy these two major mechanisms degrading antenna performance, high impedance ground planes (HIGP) were designed. HIGPs made of a 2-dimensional periodic …
Finite Difference Time Domain (Fdtd) Analysis Of A Leaky Traveling Wave Microstrip Antenna, Gregory M. Zelinski
Finite Difference Time Domain (Fdtd) Analysis Of A Leaky Traveling Wave Microstrip Antenna, Gregory M. Zelinski
Theses and Dissertations
This thesis provides the groundwork that will enable the development of a lightweight, inexpensive, aerodynamic, and broadband antenna. Whether for radar or communication, an antenna with these properties would be a force multiplier for the smaller, limited payload air vehicles the United States Air Force will pursue in the coming years. Several microstrip antennas using the first higher order mode were simulated with the Finite-Difference Time-Domain (FDTD) method. The propagation constant of each antenna was extracted from the resulting field distribution for comparison with a transverse resonance approximation, measured far-field patterns, and other simulated antennas. Variations of the geometry were …
Trade Space Analysis Of Antenna Array Architecture Using System Modeling Tools, Eugene Johnson
Trade Space Analysis Of Antenna Array Architecture Using System Modeling Tools, Eugene Johnson
Theses and Dissertations
This trade study has two objectives. The first provides a trade space analysis of differing array architectures and associated radio frequency components using system-modeling tools. The second objective develops system modeling tools aiding similar analysis by other users. These objectives were accomplished by evaluating a selected group of output parameters to include overall system cost, mass, and power consumption, as well as the minimum detectable input level, system spurious free dynamic range, and selected beam spoilage parameters caused by the use of discrete phase shifters. A fixed number of designs were evaluated using simulation. The evaluation process examined input parameter …
Analysis Of Broadband Higp-Impedance Ground Plane Antenna Designs, James W. Stewart
Analysis Of Broadband Higp-Impedance Ground Plane Antenna Designs, James W. Stewart
Theses and Dissertations
This research ties together computational and experimental analysis of two types of high-impedance ground plane (HIGP) antennas. One type of antenna consists of a proposed two-layer design. The structure consists of a bowtie antenna mounted over the surface of a HIGR The proposed structure was intended to achieve a resonant frequency of 3 GHz and a bandwidth of 48%; however, a design error results in a significant mismatch in operating bands between the antenna and HIGR Experiment results indicate the structure performs poorly across the entire measured band of 2-5 GHz. A new two-layer design is developed and presented. The …
Evaluation And Analysis Of Array Antennas For Passive Coherent Location (Pcl) Systems, Baris Calikoglu
Evaluation And Analysis Of Array Antennas For Passive Coherent Location (Pcl) Systems, Baris Calikoglu
Theses and Dissertations
Passive Coherent Location (PCL) systems use a special form of a radar receiver that exploits the ambient radiation in the environment to detect and track targets. Typical transmissions of opportunity that might be exploited include television and FM radiobroadcasts. PCL implies the use of a non-radar electromagnetic sources of illumination, such as commercial radio or television broadcasts also referred as transmitters of opportunity. The use of such illumination sources means that the receiver needs to process waveforms that are not designed for radar purposes. As a consequence, the receivers for PCL systems must be much more customized than traditional receivers, …
Design And Testing Of A Lightweight, Planar Microwave Lens, Paul M. Proudfoot
Design And Testing Of A Lightweight, Planar Microwave Lens, Paul M. Proudfoot
Theses and Dissertations
This thesis documents the design, fabrication, and testing of a lightweight, planar microwave lens. The lens consists of two planar arrays of lightweight printed circuit antennas interconnected by microstrip lines whose length varies as a function of position on the lens. Microwave energy is coupled from one face of the lens to the other by means of a slot etched in the ground plane. At 8.0 GHz the lens is ten wavelengths across, is less than 1/8 inch thick, and weighs less than 4 pounds. The lens can scan a beam over a +/- 30 degree region in both the …