In this thesis, four-arm Archimedean spiral antennas are investigated, which are low profile and have compact structure. The operating frequency bands can be designed for any microwave and millimeter frequency ranges and the antenna may be utilized in any desired applications such as Global Positioning Systems, radars, navigation systems, modern satellite communications, adaptive nulling, beam shaping, and direction finding. The concept of cavity backed absorber-filled structure along with a small ground plane embedded inside, as an inexpensive and wideband balun, is employed to reduce the axial size of the antenna. The antenna can generate broadside and boresight-null radiation patterns at the dominant and higher order modes, respectively. The study demonstrates that the proposed compact structure successfully supports the excitation of higher order modes. Polarization diversity of spiral antennas is mathematically described for an N-arm spiral antenna along with the required feeding networks. Realization of circularly-polarized broadside radiation patterns, with both senses of polarization, is then elaborated for a center-fed low-profile four-arm Archimedean spiral antenna. The radiation active zones, for generating both right- and left-handed circular polarization waves, are determined and the antenna performance in a frequency band, shared by both senses of polarization, is investigated. The developed antennas can be utilized in frequency reuse applications to enhance the wireless channel capacity and as primary feeds in high gain reflector antennas. Their performance in small front-fed parabolic reflector antennas is numerically investigated. It is shown that excellent circular polarization performance, with a remarkable radiation pattern symmetry and axial ratios below 0.5dB, low cross polarization components, and reflector total efficiencies, as high as 77.8% can be attained. Moreover, backward radiation properties of center-fed four-arm Archimedean spiral antennas are also explored, and their possible applications in reflector antennas are presented. Finally, the proposed dual-polarized spiral antennas are further investigated by dielectric loading, for size reduction purposes and frequency tuning applications. Both full and partial dielectric loadings are considered and investigated for the spiral antenna performance. A grooved dielectric substrate is also utilized to enable generating low-contrast dielectric permittivities. The spiral antenna performance, etched on such a grooved substrate, is similarly investigated. / February 2015

Thesis (M.S.E.E.)--University of Puerto Rico, Mayagüez Campus, 2004. / Printout. Tables. Includes bibliographical references (leaves 122-124).

Novel compact antenna designs for WiMAX (Worldwide interoperability for microwave access) operation in the mobile phone are presented in this thesis. In the first design, the antenna is integrated at one corner of system circuit board of the mobile phone and consists of two radiating portions; the monopole slot is formed by integrating the two portions. In the second design, two different antenna structures are used to achieve all WiMAX operating bands. Finally, in the third design, the chip antenna comprises a resonant monopole patch, a resonant shorter slot and a matching longer slot. The latter two slots are embedded within the monopole patch to achieve a compact integration. Detailed antenna designs and experimental results are presented and discussed.

Thesis (M.S. in Electrical Engineering)--Naval Postgraduate School, March 2003. / Thesis advisor(s): Jovan Lebaric, Richard W. Adler. Includes bibliographical references (p. 49). Also available online.

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Thesis (M.S.)--Michigan State University. Dept. of Electrical and Computer Engineering, 2008. / "Thesis advisor, Dr. Edward J. Rothwell"--Acknowledgments. Title from PDF t.p. (viewed on July 29, 2009) Includes bibliographical references (p. 171-174). Also issued in print.

Thesis (M.S.)--University of Wisconsin--Madison, 1982. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaf 75).

Thesis (Ph.D)--Electrical and Computer Engineering, Georgia Institute of Technology, 2010. / Committee Chair: Scott, Waymond; Committee Member: Eslinger, Owen; Committee Member: Ingram, Mary; Committee Member: Peterson, Andrew; Committee Member: Smith, Glenn. Part of the SMARTech Electronic Thesis and Dissertation Collection.

Yes / In this paper, a conical horn antenna has been designed for Ultra-Wideband ap-plications by loading its section with a metamaterial. The work aims first to compare results obtained by the wavelet-moment method to a simulation performed using HFSS. Secondly the conical horn is loaded with a very thin layer of metamaterial to enhance the radiation pattern and the bandwidth performance of the conical horn antenna and reduce the size of the antenna. The operating bandwidth of the proposed antenna is in the range of 10{13 GHz. The results obtained from HFSS and moment method are in good agreement. / Electronics and Telecommunications