Author:  Yuan, Xin 
Title:  Diversely polarized antennaarray signal processing 
Degree:  Ph.D. 
Year:  2012 
Subject:  Antenna arrays. Signal processing. Electromagnetism. Antenna arrays. Polarization (Electricity) Hong Kong Polytechnic University  Dissertations 
Department:  Dept. of Electronic and Information Engineering 
Pages:  101 p. : ill. ; 30 cm. 
Language:  English 
OneSearch:  https://www.lib.polyu.edu.hk/bib/b2522719 
URI:  http://theses.lib.polyu.edu.hk/handle/200/6609 
Abstract:  The dissertation is composed of three distinct but related components, which relate to direction finding and/or polarization estimation with diversely polarized antenna arrays. The three parts are briefly summarized below: (1) "Vector crossproduct directionfinding" with an electromagnetic vectorsensor of six orthogonally oriented but spatially noncollocating dipoles / loops. Directionfinding capability has recently been advanced by synergies between the customary approach of interferometry and the new approach of "vector cross product" based Poyntingvector estimator. The latter approach measures the incident electromagnetic wavefield for each of its six electromagnetic components, all at one point in space, to allow a vector crossproduct between the measured electricfield vector and the measured magneticfield vector. This would lead to the estimation of each incident source's Poyntingvector, which (after proper normnormalization) would then reveal the corresponding Cartesian directioncosines, and thus the azimuthelevation arrival angles. Such a "vector cross product" algorithm has been predicated on the measurement of all six electromagnetic components at one same spatial location. This physically requires an electromagnetic vectorsensor, i.e., three identical but orthogonally oriented electrically short dipoles, plus three identical but orthogonally oriented magnetically small loops all spatially collocated in a pointlike geometry. Such a complicated "vectorantenna" would require exceptionally effective electromagnetic isolation among its six componentantennas. To minimize mutual coupling across these collocated antennas, considerable antennascomplexity and hardware cost could be required. Instead, Chapter 2 shows how to apply the "vector crossproduct" directionofarrival estimator, even if the three dipoles and the three loops are located separately (instead of collocating in a pointlike geometry). This new scheme has great practical value, in reducing mutual coupling, in simplifying the antennas hardware, and in extending the spatial aperture to refine the directionfinding accuracy by orders of magnitude. (2) Various triadcompositions of collocated dipoles/loops, for direction finding & polarization estimation. To form a collocated triad of orthogonally oriented dipole(s) and/or loop(s), 20 different compositions are possible and these compositions are investigated in Chapter 3. For each such composition: (i) closedform formulas are produced here to estimate the azimuthelevation directionofarrival and the polarizationparameters, or (ii) reasoning is given why such estimation is inviable. (3) Polarization estimation with a dipoledipole pair, a dipoleloop pair, or a looploop pair of various orientations. Chapter 4 aims to estimate the polarization of fully polarized sources, given prior knowledge of the incident sources' azimuthelevation directionsofarrival, using a pair of diversely polarized antennas two electrically small dipoles, or two small loops, or one each. The pair may be collocated, or spatially separated by a known displacement. Each antenna may orient along any Cartesian coordinate. Altogether, fifteen antenna/orientation configurations are thus possible. For each configuration, Chapter 4 derives (i) the closedform polarizationestimation formulas, (ii) the associated CramerRao bounds, and (iii) the associated computational numerical stability. 
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