الفهرس 
chapter 1Only 14 pages are availabe for public view
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Abstract
This thesis introduces a study for reconfigurable shaped beams synthesis using different array geometries. A shaped radiation pattern from 2D planar and 3D conformal antenna arrays based on phase-only synthesis technique using particle swarm optimization is introduced. The 2D planar sunflower and 3D conformal arrays, cylindrical helical and spherical helical arrays are investigated. Different radiation pattern constrains are employed in the synthesis process for beam shaping. A single narrow and flat-top beams are estimated using the 2D planar sunflower array. Using the same phase distribution, two narrow beams and flat-top beams are estimated in different planes. A 3D conformal arrays, cylindrical and spherical helical arrays consist of four orthogonally oriented arms are proposed. The proposed structure introduces four independent beams in four different directions separately. Also, simultaneous four beams are obtained. The side lobe level (SLL) of the synthesized patterns is optimized below -17 dB. Also, smart multiple shaped beams synthesis from different dipole antenna arrays are studied using the method of moments (MoM) and particle swarm optimization (PSO) techniques. To overcome the storage capacity and computational time limitations of the MoM, the wavelet packet transform (WPT) is employed. The MoM/WPT result in a sparse matrix after a thersholding process. A single-ring circular array with 40 elements is designed for single beam switching. The MoM/WPT introduces a matrix compression ratio of 26.2 %, and execution time of 0.025 sec. Multiple-ring circular dipole arrays are demonstrated for single, or multiple beams. 2D planar
Abstract
III
dipole array arranged in sunflower arrangement and 3D dipole array arranged in cylindrical helical arrangements are optimized for single and dual beams in different directions. WPT compresses the matrix by 27 % and decreases execution time by 80 %. Switched beam in 60o, 120o, and 240o are estimated with high directivity and low SLL. Furthermore, a design of half-wave dipole antenna array in linear and planar fractal arrangements are introduced. The dipole array elements are positioned at the tip points of Koch fractal curve. The proposed arrangement introduces a compact design of the fractal array with low mutual coupling and no grating lobes. The method of moments (MoM) and the wavelet packet transform (WPT) are used for efficient analysis of different antenna arrays. Different array geometries with single, dual, four Koch fractal curves are designed. The MoM/WPT reduces the non-zero elements in the matrix with compression ratio of 80 % which reduces the matrix inversion computational time to 0.0103 sec. The PSO algorithm estimates the voltage phase shift excitations of the dipole elements along the single arm Koch fractal. The radiation patterns of single ring and nested-ring Koch fractal curves are investigated.
All array analysis is achieved in a computer using home programmed MATLAB and FORTRAN codes with the inter-element coupling and edge effects are considered.