A Frequency Domain Approach For Time-reversal Of Microwave Impulses

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Title: A Frequency Domain Approach For Time-reversal Of Microwave Impulses
Author: Sha, Shaoshu
Abstract: In this thesis , a compact and low -cost electronic circuit system is designed for time -reversal of microwave impulses with nanosecond and sub -nanosecond temporal durations . A frequency domain approach is adopted in order to avoid high sampling rate in time . The proposed system obtains the discrete spectra of input impulses first , then realizes time -reversal in frequency domain , and finally synthesizes the time -reversed impulses using discrete continuous wave elements . It is composed of commercially available circuits including oscillators , mixers /multipliers , band -pass -filters , amplifiers , and switches , hence embodies low -cost system -on -chip implementation . The proposed time -reversal circuit's performance is verified by Advanced Design System (ADS ) simulations , with most non -idealities of realistic circuit components taken into account . Simulation results show that , microwave impulses with about 1 ns temporal width and 3 - 10 GHz spectral coverage are reliably reversed in time , even with presence of strong noise . Furthermore , the proposed time -reversal circuit system is validated in the context of electromagnetic propagation in complex environments . Specifically , circuit -electromagnetic co -simulation is carried out to investigate the "focusing" phenomena of time -reversal . A full -wave Maxwell's equations solver based on Finite Difference Time Domain (FDTD ) method is developed to model electromagnetic propagation , and it is coupled to ADS circuit simulator . The FDTD solver is implemented on parallel cluster Message Passing Interface (MPI ) , in order to relieve high computational complexity due to complex environments . Two real -world problems (one is for wireless communication and the other is for radar detection ) are investigated . Desired "focusing" phenomena in both space and time are demonstrated by the simulation results , which conclude that the proposed time -reversal system can be deployed in practical time -reversal communication and radar applications .
URI: http : / /hdl .handle .net /10106 /1787
Date: 2009-09-16


A Frequency Domain Approach For Time-reversal Of Microwave Impulses. Available electronically from http : / /hdl .handle .net /10106 /1787 .

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