Near-Field Error Analysis for Arbitrary Scanning Grids Using Fast Irregular Antenna Field Transformation Algorithm

Qureshi, M. Ayyaz; Schmidt, Carsten H.; Eibert, Thomas F.

doi:10.2528/pierb12121502

Cited by 16 publications

(3 citation statements)

References 30 publications

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“…In [4], the authors have presented a novel approach to estimate the FF uncertainty using the fast irregular antenna field transformation algorithm, which can be utilized in planar, cylindrical, and spherical NF measurements, as well as arbitrary measurement grids. However, the article lacks a clear explanation regarding the procedure for acquiring reference FF data.…”

Section: Introduction 1background and Motivationmentioning

confidence: 99%

Near-to-Far Field RCS Calculation Using Correction Optimization Technique

2023

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Radar cross section (RCS) is a scattering measure of an object that scatters to the radar. However, existing methods for near-field (NF) measurement and data processing rarely extract amplitude characteristics, and there is a lack of effective verification of far-field (FF) data in the process of NF to FF transformation, which leads to inaccuracies in FF prediction accuracy. In this paper, we propose a method to establish the relationship between the NF and FF RCS using the state space method (SSM), which is based on accurate estimation of the NF amplitude in NF measurement, and then deriving the FF RCS from the NF scattering signal convolved with a near-to-far kernel. The proposed solution to address the uncertainty issue in reference FF data involves using the geometric theory of diffraction (GTD) scattering center model as the reference FF data and establishing a linear equation with the derived FF model. The negative gradient search (NGS) system identification concept is used to optimize the FF model in order to reduce the discrepancy between the reference and derived values. Finally, the corrected RCS error is provided as additional proof of the effectiveness of these techniques in enhancing near-to-far transformation accuracy by examining the outcomes of three experiments.

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Section: Introduction 1background and Motivationmentioning

confidence: 99%

Near-to-Far Field RCS Calculation Using Correction Optimization Technique

2023

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“…Further capabilities of FIAFTA including the efficient treatment of non-redundant measurements [29,30], echo suppression techniques by inward and outward looking measurement probes [31], volumetric imaging by hierarchical disaggregation of broadband field observations [32], efficient transformation of phaseless field measurements with first results [18,19], and the utilization of FIAFTA within non-linear inverse material problem solutions [14,15,33] are found in the given references. Extensive error investigations are presented in [34]. Recently, the FIAFTA concept was extended for the NFFF transformation of monostatic radar cross section measurements [35].…”

Section: Introductionmentioning

confidence: 99%

ELECTROMAGNETIC FIELD TRANSFORMATIONS FOR MEASUREMENTS AND SIMULATIONS (Invited Paper)

Eibert¹,

Kılıç²,

Lopez³

et al. 2015

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125

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Abstract-Electromagnetic field transformations are important for electromagnetic simulations and for measurements. Especially for field measurements, the influence of the measurement probe must be considered, and this can be achieved by working with weighted field transformations. This paper is a review paper on weighted field transformations, where new information on algorithmic properties and new results are also included. Starting from the spatial domain weighted radiation integral involving free space Green's functions, properties such as uniqueness and the meaning of the weighting function are discussed. Several spectral domain formulations of the weighted field transformation integrals are reviewed. The focus of the paper is on hierarchical multilevel representations of irregular field transformations with propagating plane waves on the Ewald sphere. The resulting Fast Irregular Antenna Field Transformation Algorithm (FIAFTA) is a versatile and efficient transformation technique for arbitrary antenna and scattering fields. The fields can be sampled at arbitrary irregular locations and with arbitrary measurement probes without compromising the accuracy and the efficiency of the algorithm. FIAFTA supports different equivalent sources representations of the radiation or scattering object: 1) equivalent surface current densities discretized on triangular meshes, 2) plane wave representations, 3) spherical harmonics representations. The current densities provide for excellent spatial localization and deliver most diagnostics information about the test object. A priori information about the test object can easily be incorporated, too. Using plane wave and spherical harmonics representations, the spatial localization is not as good as with spatial current densities, but still much better than in the case of conventional modal expansions. Both far-field based expansions lead to faster transformations than the equivalent currents and in particular the orthogonal spherical harmonics expansion is a very attractive and robust choice. All three expansions are well-suited for efficient echo suppression by spatial filtering. Various new field transformation and new computational performance results are shown in order to illustrate some capabilities of the algorithm.

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“…In this paper, the fast irregular antenna field transformation algorithm (FIAFTA) (Qureshi et al, 2013) is utilized and adapted for the processing of phaseless data. FIAFTA is based on multi-level fast multipole method (MLFMM) principles (Chew et al, 2001).…”

Section: Introductionmentioning

confidence: 99%

Fast near-field far-field transformation for phaseless and irregular antenna measurement data

et al. 2014

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Abstract. The characterization of antenna radiation patterns by transformed near-field measurements requires accurate amplitude and phase data. This represents a problem since expensive measurement equipment is required, especially at millimeter and submillimeter wavelengths (Isernia et al., 1996). Amplitude-only antenna field measurements are theoretically sufficient for the unique determination of antenna far-fields. Therefore, phaseless techniques are of special interest. However, the required field transformations are extremely challenging, since they are nonlinear and strongly ill-posed. In this work, the amplitude-only or phaseless near-field far-field transformation problem is formulated as a nonlinear optimization problem. The linear radiation operator within the nonlinear formulation is evaluated using the fast irregular antenna field transformation algorithm (FIAFTA). A hybrid solution procedure is described which combines a genetic algorithm with an iterative conjugate gradient (CG) search method. Numerical results prove the efficiency and flexibility of the formulation and it is shown that the algorithm remains stable when the noise level in the measurements is moderate. Nevertheless, regularization techniques might be beneficial to further improve the robustness of the algorithm.

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Near-Field Error Analysis for Arbitrary Scanning Grids Using Fast Irregular Antenna Field Transformation Algorithm

Cited by 16 publications

References 30 publications

Near-to-Far Field RCS Calculation Using Correction Optimization Technique

Near-to-Far Field RCS Calculation Using Correction Optimization Technique

ELECTROMAGNETIC FIELD TRANSFORMATIONS FOR MEASUREMENTS AND SIMULATIONS (Invited Paper)

Fast near-field far-field transformation for phaseless and irregular antenna measurement data

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