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Title: Eliminating array manifold and mutual coupling uncertainties
Author: Fistas, Nikolaos
ISNI:       0000 0004 2737 3093
Awarding Body: Imperial College London
Current Institution: Imperial College London
Date of Award: 1994
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In spite of the potential advantages of Signal-Subspace-type techniques (eigenstructure techniques), these techniques have not yet been, extensively utilised in practical applications. The reason for this is related to uncertainties with respect to the geometrical and electrical characteristics of the array (array calibration problem), and to uncertainties relating to the mutual coupling between the array elements. This thesis investigates ways to estimate the errors due to these uncertainties and proposes solutions based on the use of some known pilot sources. Initially, the mathematical modelling of the errors associated with the calibration problem is presented. The effects of the geometrical and electrical errors are incorporated into the Manifold Perturbation Vector. In addition the modelling of the mutual coupling effects is presented. The effects of mutual coupling are modelled in the form of a complex square matrix, the Mutual Coupling Matrix. Two new techniques are proposed for calibrating an array of receiving elements with respect to errors in location, phase and gain, even when all types of errors are present at the same time. The main characteristic of these two new techniques is that they differentiate between the physical and the electrical locations of the array elements. One of the proposed techniques is based on the optimisation of a suitable cost function with respect to the relevant calibration parameters and can be implemented in a number of different ways depending on the characteristics of the array used. The other technique is based on the solution of a set of equations. Calibration of single-type errors can be seen as a special case of the general approach in both techniques. In addition, a technique is proposed for estimating the mutual coupling between the elements of an array. The proposed technique employs one pilot source and uses an extra element at some distance away from the other elements, so that its mutual coupling contribution will be negligible. All the proposed techniques are supported by computer simulation studies. Furthermore, the performance of the proposed techniques is investigated in the case where only a finite number of samples of the received signal is available (finite averaging effects).
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available