Design and analysis of pattern null reconfigurable antennas

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.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Electrical & Computer Engr

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2012

Author dc:creator

• Yong, Siwen

Contributors dc:contributor

• Bernhard, Jennifer T.
• Cangellaris, Andreas C.
• Schutt-Ainé, José E.
• Franke, Steven J.

• Pattern reconfigurable antenna
• Null reconfiguration
• intermodulation distortion (IMD)

Statement dc:rights

• Copyright 2012 Siwen Yong

Language dc:language

en

Handle dc:identifier

http://hdl.handle.net/2142/31106

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/31106