Design and development of a hybrid near field and far field antenna measurement system, The
Advisor
Elsherbeni, Atef Z.Date issued
2021Keywords
antenna measurementsfar field measurements
near field measurements
near field to far field transformation
software interface
Metadata
Show full item recordAbstract
In this thesis, a dual-purpose antenna chamber measurement system is presented. The measurement system is an anechoic chamber where the near-fields or far-fields of an antenna can be measured with the same equipment. A custom software was developed to perform either type of measurement. This antenna chamber is a much more cost-effective solution compared to conventional antenna chambers, where separate chambers are used for different types of measurements. This thesis presents the developed software and hardware for a custom-made chamber design that produces accurate results. Both mechanical and software capabilities are introduced, but emphasis is put on the development of the software capabilities throughout this thesis. Both theoretical, numerical, and experimental analysis is introduced to verify the performance of the chamber. The necessary methods to perform the near-field to far-field transformations are presented and discussed in detail. A circular patch antenna is designed, simulated and tested to verify the accuracy of the far fields measured in the chamber, and a broadband horn antenna is measured to verify the accuracy of the near field measurements. The measured results for these two types of antennas matched the expected results, verifying the accuracy of each measurement type. Lastly, an antenna array is tested using both far field and near field systems, and the results from both measurement system were compared with each other. Good agreement is obtained, but due to the physical limitations related to the equipment used in the chamber and the size of the antenna some differences in the far field patterns are observed.Rights
Copyright of the original work is retained by the author.Collections
Related items
Showing items related by title, author, creator and subject.
-
Yampa coal field, Colorado: Moffat Tunnel will make field accessible: accompanied by chart (2 sheets): "Proximate analyses of samples of coal from the Yampa coal field, Moffat & Routt Counties, Colorado; all analyses made by the United States Bureau of Mines": 1924 Dept. of the Interior release 17848, TheEby, J. Brian (James Brian), 1896-; Geological Survey (U.S.); United States. Bureau of Mines
-
Integrated wellbore stability analysis for well trajectory optimization and field development: the West Kazakhstan FieldTutuncu, Azra; Kadyrov, Tlek; Graves, Ramona M.; Fleckenstein, William W.; Bratton, Tom (Colorado School of Mines. Arthur Lakes Library, 2012)Severe wellbore-stability issues such as stuck pipe, sidetracking of wells and incomplete pipe-conveyed-logging operations have been encountered during drilling horizontal wells in the West Kazakhstan Field. To contribute to solutions of these issues, an integrated wellbore-stability study was implemented to effectively plan the future drilling operations in the West Kazakhstan Field, to maximize the drilling margin for the future wells drilled, and to optimize the future field development. Typically, only a rock mechanics component for wellbore-stability analysis has been used to obtain wellbore-stability numerical models. In this study, however, the rock mechanical model was coupled with the mechanical stress, temperature alteration, shale-fluid physicochemical interaction, and the flow-induced stress using the Mohr-Coulomb and Mogi-Coulomb failure criteria. The problem diagnosis is a very important part of any wellbore-stability analysis. A special wellbore-stability problem-diagnostic scheme was first used to identify problematic horizons. The possible causes of the wellbore-stability issues were narrowed down. The well trajectory, drilling-fluid density, and types of water-based mud were confirmed to have a dominant impact on the occurrence of the wellbore-stability problems in West Kazakhstan Field. Dipole sonic, imaging, and sonic scanner logs were utilized to obtain in-situ stresses and formation properties. The strike-slip regime was identified in the study field. Pore pressure was predicted in the interest intervals within the West Kazakhstan Field utilizing the Eaton method with significant modifications of the Eaton's compaction coefficients. The stochastic risk and sensitivity analysis was conducted to evaluate the sensitivity of the obtained input data on the study outcome. The Mogi-Coulomb formation failure criterion was found to be a better characterization of the brittle rock failure in the West Kazakhstan Field as utilization of the Mohr-Coulomb failure criterion resulted in overestimation of the wellbore collapse pressure, probably due to ignoring the strengthening effect of the intermediate principle stress. The results of this study could benefit the mitigation and/or prevention of wellbore-stability issues in the West Kazakhstan Field.
-
Field verification of stream-aquifer interactions: Colorado School of Mines survey field, Golden, ColoradoPoeter, Eileen; Anderman, Evan R. (Colorado School of Mines. Arthur Lakes Library, 1993)