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Gabor's original holography, which is the basic theory of modern microwave holographic techniques, is introduced. By computer simulations, it is demonstrated that the conventional holographic approach can be used as a tool to reconstruct aperture field distributions of an antenna with some constraints. Computer simulations of the theory and technique of the improved microwave holographic approach originally introduced by Rahmat-Samii et al. are carried out. The results show that it can be used for surface distortion diagnosis of large reflector antennas. The physical optics integral formulation is derived by general solutions of the vector wave equations. The necessary theory , which is needed to reconstruct the aperture field from near-field measurements both in a rectangular coordinate system and in a cylindrical coordinate system is developed. It is based on the plane wave spectrum and the vector wave modal expansion of an electromagnetic field. By using a simple dipole and other well-defined antennas, computer simulations have been performed. The results show that the technique is rigorous and applicable. It is also demonstrated that the sampling intervals and the number of sampling points should be chosen carefully in order to obtain a satisfactory resolution of the reconstructed aperture field. Furthermore, the simulations carried out in this work reveal that the real aperture field distribution of a dipole antenna has a maximum point at each end of the antenna. This characteristic can only be obtained at a very close distance to the antenna. This study also reveals the significant contributions of the evanescent waves to the aperture reconstruction. A simple but effective method for examining the evanescent waves from the measured near-field is also presented. By using dipoles and other well known antennas and antenna arrays, the experiments were carried out. The experimental results provide reasonable good agreements with the simulations. The technique proposed is effective and accurate. / Doctor of Philosophy (PhD)

Bibliography : leaves i-xx / xi, 168, [99], xx leaves : ill ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Physics and Mathematical Physics, 1991

Thesis (Ph. D.)--University of Texas at Austin, 2006. / Vita. Includes bibliographical references.

Thesis (Ph. D.)--Ohio State University, 2006. / Title from first page of PDF file. Includes bibliographical references (p. 96-98).

Abstract Because of the rapid development of mobile communications, the bandwidth efficiency and the communication quality have become interesting issues for researchers. Multipath fading and multiple-access interference (MAI) are the main barriers of performance improvement. Fortunately, spread spectrum techniques have an inherent ability of anti-interference and anti-multipath. Thus, the commercialized CDMA systems are developed on the basis of spread spectrum techniques. Recently, smart antennas using adaptive array techniques have been applied in CDMA communications. There are two different approaches to realize smart antenna systems: one is named as ¡¥switching-beam arrays¡¦; the other is called ¡¥tracking-beam arrays¡¦. Switching-beam arrays use a number of fixed beams at an antenna site. The mobiles select the beam that offers the best signal enhancement and interference reduction. On the other hand, tracking-beam arrays can adjust their pattern to track desired signals, reduce interference, and collect correlated multipath power. In this thesis, several smart antenna systems based on tracking-beam arrays in DS-CDMA systems are developed. The proposed smart antennas comprise two main structures, i.e., the direction-of-arrival (DOA) tracking and the dynamic beamforming. The improved recursively updated method and the Kalman filter algorithm are employed to track the mobiles¡¦ DOAs. By referring to the estimated DOA, the minimum- variance-distortionless-response (MVDR) dynamic beamformer produces a main beam to target on a certain mobile and simultaneously, interferences from other mobiles are suppressed. Therefore, the MAI in DS-CDMA systems can be suppressed properly at all times. Besides, the inherent processing gain in DS-CDMA systems is utilized to break through the limit that the number of mobiles must be smaller than that of sensors. The proposed smart antennas work properly even the number of mobiles exceeds that of sensor. Simulation results show that the advantages of the proposed technique over the conventional tracking-beam arrays.

Thesis--Auburn University, 2008. / Abstract. Vita. Includes bibliographic references (p.65-67).

Thesis (Ph. D.)--Brigham Young University. Dept. of Electrical and Computer Engineering, 2004. / Includes bibliographical references (p. 129-145).

Thesis (Ph.D)--Electrical and Computer Engineering, Georgia Institute of Technology, 2009. / Committee Chair: Ingram, Mary Ann; Committee Member: Durgin, Greg; Committee Member: Kenney, Steve; Committee Member: Landgren, Jack; Committee Member: Li, Ye. Part of the SMARTech Electronic Thesis and Dissertation Collection.

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