Analysis and design of compact low profile antennas for fixed volume applications

Van Niekerk, Carlo

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https://hdl.handle.net/2142/44284 Copy

Description

Title

Analysis and design of compact low profile antennas for fixed volume applications

Author(s)

Van Niekerk, Carlo

Issue Date

2013-05-24T22:06:32Z

Director of Research (if dissertation) or Advisor (if thesis)

Bernhard, Jennifer T.

Doctoral Committee Chair(s)

Bernhard, Jennifer T.

Committee Member(s)

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

Department of Study

Electrical & Computer Eng

Discipline

Electrical & Computer Engr

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

Ph.D.

Degree Level

Dissertation

Keyword(s)

• Electrically small antennas
• Planar Inverted-F Antenna (PIFA)
• Metamaterials
• Gustafsson's limit
• Top-loaded Monopole

Abstract

In this document we have accomplished a number of tasks that bring value to the field. A circuit analysis was performed on a transmission line based metamaterial antenna (in particular, the Infinite Wavelength Resonant Antenna or IWRA). It was discovered that the antenna works in similar manner to traditional coupled transmission lines. In fact, further investigation using characteristic mode theory showed that the IWRA could be thought of simply as two closely coupled Planar Inverted-F Antennas (PIFAs) that are proximity-couple fed. The concept of a Dual Reactively Loaded Monopole (DRLM) antenna is introduced, an antenna that features capacitive and inductive loading components. This new design allows for miniaturized performance with the benefit of tunability. The implementation of the DRLM antenna where the inductive loading is achieved by a lumped inductor as opposed to the conventional distributed copper strip shows relatively good performance when compared to the fundamental limit. This study demonstrates the viability of inductive loading by lumped element for radiating structures. The optimum position for the lumped inductor is determined by experimental means. The DRLM antenna with reduced height profile is analyzed, and it is determined that the antenna architecture is not well suited to extreme low profile applications (e.g., short-fat topology). Finally, a Stacked DRLM antenna is designed for the purpose of achieving wider impedance bandwidth. The final design has a bandwidth more than double the original single mode DRLM antenna, though now the tunability is limited. All antennas discussed are compared to the theoretical limits for antenna performance, and specific antenna structures are evaluated against Gustafsson's limit for the appropriate volume that best describes the antenna geometry. This presents a more realistic performance comparison than the spherical volume counterpart, Chu's limit.

Graduation Semester

2013-05

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http://hdl.handle.net/2142/44284

Copyright and License Information

Copyright 2013 Carlo Van Niekerk

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