| Author: | Yuan, Xin |
| Title: | Diversely polarized antenna-array signal processing |
| Degree: | Ph.D. |
| Year: | 2012 |
| Subject: | Antenna arrays. Signal processing. Electromagnetism. Antenna arrays. Polarization (Electricity) Hong Kong Polytechnic University -- Dissertations |
| Department: | Department of Electronic and Information Engineering |
| Pages: | 101 p. : ill. ; 30 cm. |
| Language: | English |
| 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 cross-product direction-finding" with an electromagnetic vector-sensor of six orthogonally oriented but spatially non-collocating dipoles / loops. Direction-finding capability has recently been advanced by synergies between the customary approach of interferometry and the new approach of "vector cross product" based Poynting-vector 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 cross-product between the measured electric-field vector and the measured magnetic-field vector. This would lead to the estimation of each incident source's Poynting-vector, which (after proper norm-normalization) would then reveal the corresponding Cartesian direction-cosines, and thus the azimuth-elevation 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 vector-sensor, i.e., three identical but orthogonally oriented electrically short dipoles, plus three identical but orthogonally oriented magnetically small loops all spatially collocated in a point-like geometry. Such a complicated "vector-antenna" would require exceptionally effective electro-magnetic isolation among its six component-antennas. To minimize mutual coupling across these collocated antennas, considerable antennas-complexity and hardware cost could be required. Instead, Chapter 2 shows how to apply the "vector cross-product" direction-of-arrival estimator, even if the three dipoles and the three loops are located separately (instead of collocating in a point-like 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 direction-finding accuracy by orders of magnitude. (2) Various triad-compositions 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) closed-form formulas are produced here to estimate the azimuth-elevation direction-of-arrival and the polarization-parameters, or (ii) reasoning is given why such estimation is inviable. (3) Polarization estimation with a dipole-dipole pair, a dipole-loop pair, or a loop-loop pair of various orientations. Chapter 4 aims to estimate the polarization of fully polarized sources, given prior knowledge of the incident sources' azimuth-elevation directions-of-arrival, 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 closed-form polarization-estimation formulas, (ii) the associated Cramer-Rao bounds, and (iii) the associated computational numerical stability. |
| Rights: | All rights reserved |
| Access: | open access |
Files in This Item:
| File | Description | Size | Format | |
|---|---|---|---|---|
| b25227191.pdf | For All Users | 1.66 MB | Adobe PDF | View/Open |
Copyright Undertaking
As a bona fide Library user, I declare that:
- I will abide by the rules and legal ordinances governing copyright regarding the use of the Database.
- I will use the Database for the purpose of my research or private study only and not for circulation or further reproduction or any other purpose.
- I agree to indemnify and hold the University harmless from and against any loss, damage, cost, liability or expenses arising from copyright infringement or unauthorized usage.
By downloading any item(s) listed above, you acknowledge that you have read and understood the copyright undertaking as stated above, and agree to be bound by all of its terms.
Please use this identifier to cite or link to this item:
https://theses.lib.polyu.edu.hk/handle/200/6609