Ultra wideband antenna array processing under spatial aliasing

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Title: Ultra wideband antenna array processing under spatial aliasing
Author: Shapoury, Alireza
Abstract: Given a certain transmission frequency , Shannon spatial sampling limit de ?nes an upper bound for the antenna element spacing . Beyond this bound , the exceeded ambiguity avoids correct estimation of the signal parameters (i .e . , array manifold crossing ) . This spacing limit is inversely proportional to the frequency of transmis - sion . Therefore , to meet a wider spectral support , the element spacing should be decreased . However , practical implementations of closely spaced elements result in a detrimental increase in electromagnetic mutual couplings among the sensors . Further - more , decreasing the spacing reduces the array angle resolution . In this dissertation , the problem of Direction of Arrival (DOA ) estimation of broadband sources is ad - dressed when the element spacing of a Uniform Array Antenna (ULA ) is inordinate . It is illustrated that one can resolve the aliasing ambiguity by utilizing the frequency diversity of the broadband sources . An algorithm , based on Maximum Likelihood Estimator (MLE ) , is proposed to estimate the transmitted data signal and the DOA of each source . In the sequel , a subspace -based algorithm is developed and the prob - lem of order estimation is discussed . The adopted signaling framework assumes a subband hopping transmission in order to resolve the problem of source associations and system identi ?cation . The proposed algorithms relax the stringent maximum element -spacing constraint of the arrays pertinent to the upper -bound of frequency transmission and suggest that , under some mild constraints , the element spacing can be conveniently increased . An approximate expression for the estimation error has also been developed to gauge the behavior of the proposed algorithms . Through con - ?rmatory simulation , it is shown that the performance gain of the proposed setup is potentially signi ?cant , speci ?cally when the transmitters are closely spaced and under low Signal to Noise Ratio (SNR ) , which makes it applicable to license -free communication .
URI: http : / /hdl .handle .net /1969 .1 /ETD -TAMU -1495
Date: 2009-05-15

Citation

Ultra wideband antenna array processing under spatial aliasing. Available electronically from http : / /hdl .handle .net /1969 .1 /ETD -TAMU -1495 .

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