Abstract
This paper investigates the problem of mixed far-field (FF) and near-field (NF) source localization using a linear electromagnetic-vector-sensor array with gain/phase uncertainties. Firstly, several special fourth-order cumulant matrices are constructed, such that the shift invariance structure in the cumulant domain can be derived to estimate the DOA and polarization angles of each source at two electromagnetic vector sensors (EMVSs). Then, by computing the determinant of the coefficient matrix, the sources types can be classified with the prior knowledge of the number of both the FF and NF sources. On this basis, the range of NF sources and the DOAs of mixed sources at the phase reference point are captured subsequently. Finally, these estimates can be employed to generate the unknown gain/phase errors. Compared to the existing methods, the proposed one exploits both the spatial and polarization information of sources and provides a satisfactory parameters estimation performance under unknown phase/gain responses. Moreover, it does not need to perform any spectral search and not impose restriction on EMVSs placement, as well as realizes a more reasonable classification of the signal types. Simulations are carried out to verify the effectiveness of the proposed method.
Highlights
In recent years, the problem of measuring spatial and polarization information of electromagnetic signals using vector sensor array has attracted increasing research, and numerous algorithms [1]–[8] have been developed for parameters estimation of far-field (FF) sources, whose wavefront is assumed to be a plane wave
In some practical applications, such as locating specific items in warehouses by using radio-frequency identification (RFID) tags [11], each item may be in the nearfield or far-field of the RFID reader antenna array, and both FF and NF sources may coexist in such environment
We propose a novel algorithm for mixed source localization using a linear electromagnetic vector sensors (EMVSs) array with gain/phase uncertainties
Summary
The problem of measuring spatial and polarization information of electromagnetic signals using vector sensor array has attracted increasing research, and numerous algorithms [1]–[8] have been developed for parameters estimation of far-field (FF) sources, whose wavefront is assumed to be a plane wave. In view of the previous analyses, most existing algorithms face the following difficulties: 1) measuring the spatial and polarization parameters of mixed sources; 2) localizing the mixed sources successfully with polarization sensitive array in the presence of gain/phase errors; 3) classifying the FF and NF sources reasonably; 4) avoiding spectral search. To solve these difficulties, we propose a novel algorithm for mixed source localization using a linear EMVS array with gain/phase uncertainties. The (·)T , (·)∗, (·)H and ⊗ denote the transpose, conjugate, conjugate transpose and kronecker product, respectively. {·} denotes the argument of a complex number and diag{·} denotes a diagonal matrix. · and × denote the 2-norm and cross product, respectively
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