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Title:Design and analysis of pattern null reconfigurable antennas
Author(s):Yong, Siwen
Director of Research:Bernhard, Jennifer T.
Doctoral Committee Chair(s):Bernhard, Jennifer T.
Doctoral Committee Member(s):Cangellaris, Andreas C.; Schutt-Ainé, José E.; Franke, Steven J.
Department / Program:Electrical & Computer Eng
Discipline:Electrical & Computer Engr
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Pattern reconfigurable antenna
Null reconfiguration
intermodulation distortion (IMD)
Abstract:This dissertation presents the design, analysis, and measurement of pattern null reconfigurable antennas (NRAs). Unlike conventional pattern reconfigurable antennas, NRAs possess the ability to steer their pattern nulls, yielding interference rejection capabilities. While various NRAs exist, the current state of the art has two significant drawbacks, namely, the requirement for feed reconfiguration and the lack of null scanning capability. This dissertation develops a compact, varactor-loaded NRA that circumvents these limitations, providing measured continuous null steering up to 31 degrees off broadside at 2.42 GHz along the E plane within its common impedance bandwidth. In addition, careful consideration of the modes on the antenna illuminates the antenna's operating principles, yielding guidelines for simple NRA design at other frequencies. To improve the interference rejection capabilities of our antenna, we develop an improved NRA capable of null scanning in the complete upper hemispherical space. Both simulation and measurement confirm antenna performance. Consequently, the antenna's enhanced pattern agility provides improved performance when integrated in cognitive radios. In addition to highlighting the detrimental effects of varactor packaging parasitics, this dissertation presents a study of the impact of diode nonlinearity on antenna performance. While various authors perform two tone intermodulation distortion (IMD) measurements when characterizing reconfigurable antenna performance, an analysis of the relationship between diode linearity and fundamental antenna parameters has yet to be conducted. This dissertation addresses this need, demonstrating that reconfigurable antennas may suffer from gain compression and exhibit nonreciprocity, setting the stage for additional research to mitigate these effects.
Issue Date:2012-05-22
Rights Information:Copyright 2012 Siwen Yong
Date Available in IDEALS:2012-05-22
Date Deposited:2012-05

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