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Title: Investigation of the effect of phase conjugation and time reversal techniques in free space and reverberant environment
Author: Sundaralingam, Padmini
ISNI:       0000 0004 2745 1231
Awarding Body: Queen's University Belfast
Current Institution: Queen's University Belfast
Date of Award: 2012
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We numerically explore the performance of the time reversal approach in terms of temporal and spatial focussing in three different propagation environments: free space, partially reflected medium and fully reflected medium. Performance of the phase conjugation scheme is experimentally investigated in partially reflected medium and fully reflected medium based on the characteristics of focus sing and steering capabilities. We have explored numerically the E-field time evolution along the propagation path and the beam steering action of a 2.45 GHz time reversal retrodirective array using dipole antennas excited by a I0nS 2.45 GHz RP pulsed sinusoidal carrier. It is shown that temporal and spatially confined focussing can be achieved for a variety of different time reversal methods, un-modified, amplitude quantised and time decimated under sampled with a single transmitter and a receiver setup operating within a reverberation chamber at 2.4 GHz under RP pulsed sinewave. Also it has been shown that, by introducing various size cluttering objects into the reverberant environment, the application of classical and differential time reversal methods does not significantly affect the spatio-temporal focus sing properties of the system. The possibility of deploying multiple transmitters inside the cavity is also briefly investigated. We have numerically demonstrated that temporal, spatial focussing and beam steering action can be achieved in free space using a slot array positioned in one wall of a metal air filled cavity utilizing a single antenna time reversal system. This presents an interesting possibility for a new type of beam steered array. The phase conjugation technique is an alternative to the time reversal method, which is suitable for monochromatic signals. Various phase conjugation implementation techniques have been developed for retrodirective array deployment this thesis employs a QUB developed IQ modulator based phase conjugator. It is experimentally shown that spatial localization of the field occurs within a radius of approximately 1.5-2A around the pilot source position using the single analogue phase conjugation unit operating at 2.4GHz for spatially confined data signaling in an enclosed highly reverberant multipath rich environment.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available