Far-Field Characteristics of Discrete Parabolic Reflector Made of Circular PEC Wires, Symmetrically Illuminated by Plane Waves

2021 ◽  
Author(s):  
Elena A. Velichko
Keyword(s):  
Plane Waves ◽  
Far Field ◽  
Parabolic Reflector

scholarly journals Hybrid multilevel plane wave based near-field far-field transformation utilising combined near- and far-field translations

2009 ◽  
Vol 7 ◽  
pp. 17-22 ◽  
Author(s):  
C. H. Schmidt ◽  
T. F. Eibert
Keyword(s):  
Near Field ◽  
Measurement Techniques ◽  
Plane Waves ◽  
Low Complexity ◽  
Far Field ◽  
Computation Complexity ◽  
Low Frequencies ◽  
Field Transformation ◽  
Translation Operators ◽  
Equivalent Sources

Abstract. The radiation of large antennas and those operating at low frequencies can be determined efficiently by near-field measurement techniques and a subsequent near-field far-field transformation. Various approaches and algorithms have been researched but for electrically large antennas and irregular measurement contours advanced algorithms with low computation complexity are required. In this paper an algorithm employing plane waves as equivalent sources and utilising efficient diagonal translation operators is presented. The efficiency is further enhanced using simple far-field translations in combination with the expensive near-field translations. In this way a low complexity near-field transformation is achieved, which works for arbitrary sample point distributions and incorporates a full probe correction without increasing the complexity.

Far-field Interference and Diameter Measurement on Two Coherent Plane Waves Irradiating Sphere

2015 ◽  
Vol 44 (9) ◽  
pp. 912002
Author(s):  
李建民 LI Jian-min ◽  
牛振风 NIU Zhen-feng ◽  
王延峰 WANG Yan-feng ◽  
邵雪辉 SHAO Xue-hui ◽  
陈方 CHEN Fang ◽  
...  
Keyword(s):  
Plane Waves ◽  
Far Field ◽  
Diameter Measurement

scholarly journals Method to Determine the Far-Field Beam Pattern of A Long Array From Subarray Beam Pattern Measurements

Sensors ◽  
2020 ◽  
Vol 20 (4) ◽  
pp. 1236
Author(s):  
Donghwan Jung ◽  
Jeasoo Kim
Keyword(s):  
Conventional Method ◽  
Field Condition ◽  
Near Field ◽  
Plane Waves ◽  
Measurement Data ◽  
Beam Pattern ◽  
Far Field ◽  
Water Tank ◽  
Discrete Line ◽  
Line Array

Beam pattern measurement is essential to verifying the performance of an array sonar. However, common problems in beam pattern measurement of arrays include constraints on achieving the far-field condition and reaching plane waves mainly due to limited measurement space as in acoustic water tank. For this purpose, the conventional method of measuring beam patterns in limited spaces, which transform near-field measurement data into far-field results, is used. However, the conventional method is time-consuming because of the dense spatial sampling. Hence, we devised a method to measure the beam pattern of a discrete line array in limited space based on the subarray method. In this method, a discrete line array with a measurement space that does not satisfy the far-field condition is divided into several subarrays, and the beam pattern of the line array can then be determined from the subarray measurements by the spatial convolution that is equivalent to the multiplication of beam pattern. The proposed method was verified through simulation and experimental measurement on a line array with 256 elements of 16 subarrays.

scholarly journals Factorization method with one plane wave: from model-driven and data-driven perspectives

2021 ◽  
Author(s):  
Guanqiu Ma ◽  
Hu Guanghui
Keyword(s):  
A Priori ◽  
Plane Waves ◽  
Factorization Method ◽  
Data Driven ◽  
Field Pattern ◽  
Far Field ◽  
Model Driven ◽  
The One ◽  
Necessary And Sufficient ◽  
Mathematical Justification

Abstract The factorization method provides a necessary and sufficient condition for characterizing the shape and position of an unknown scatterer by using far-field patterns of infinitely many time-harmonic plane waves at a fixed frequency (which are also called the multistatic data response matrix). This paper is concerned with the factorization method with a single far-field pattern to recover an arbitrary convex polygonal scatterer/source. Its one-wave version relies on the absence of analytical continuation of the scattered/radiated wave-fields in corner domains. It can be regarded as a domain-defined sampling method and does not require forward solvers. In this paper we provide a rigorous mathematical justification of the one-wave factorization method and present some preliminary numerical examples. In particular, the proposed method can be interpreted as a model-driven and data-driven imaging scheme, and it shows how to incorporate a priori knowledge about the unknown target into the test scatterers for the purpose of detecting obstacles/sources with specific features.

Nonlinear Wave Propagation in Elastic Submerged Cables

1997 ◽  
Author(s):  
M. Behbahani-Nejad ◽  
N. C. Perkins
Keyword(s):  
Wave Propagation ◽  
Linear Theory ◽  
Fluid Model ◽  
Plane Waves ◽  
Three Dimensional ◽  
Hydrodynamic Drag ◽  
Far Field ◽  
Computational Domain ◽  
Nonlinear Wave Propagation ◽  
Closed Form Solutions

Abstract This paper analyzes the coupled nonlinear tangential-normal waves that propagate along underwater cable suspensions. Taken with the recently developed linear theory governing the in-plane structural waves (3) and an analysis of nonlinear out-of-plane waves for submerged cables (2), this investigation contributes further understanding toward a nonlinear three-dimensional theory for wave propagation along fluid loaded cables. The nonlinearities present in the in-plane model render the cable/fluid model intractable by exact analytical methods. A numerical solution is pursued in this study using finite difference algorithms. To this end, an infinite cable domain is divided to two sub domains, namely an interior (finite computational) domain and exterior (infinite far field) domain. Closed-form solutions for the approximate linear theory are employed for the far field in constructing nonreflecting boundary conditions for the computational domain. Numerical results highlight the governing role of nonlinear hydrodynamic drag for underwater cable suspentions.

scholarly journals Uniqueness in inverse electromagnetic scattering problem with phaseless far-field data at a fixed frequency

2020 ◽  
Author(s):  
Xiaoxu Xu ◽  
Bo Zhang ◽  
Haiwen Zhang
Keyword(s):  
Electromagnetic Scattering ◽  
Field Data ◽  
Scattering Problem ◽  
Plane Waves ◽  
Index Of Refraction ◽  
Field Pattern ◽  
Far Field ◽  
Fixed Frequency ◽  
Uniqueness Results ◽  
Far Field Pattern

Abstract This paper is concerned with uniqueness in inverse electromagnetic scattering with phaseless far-field pattern at a fixed frequency. In our previous work (2018,SIAM J. Appl. Math. 78, 3024–3039), by adding a known reference ball into the acoustic scattering system, it was proved that the impenetrable obstacle and the index of refraction of an inhomogeneous medium can be uniquely determined by the acoustic phaseless far-field patterns generated by infinitely many sets of superpositions of two plane waves with different directions at a fixed frequency. In this paper, we extend these uniqueness results to the inverse electromagnetic scattering case. The phaseless far-field data are the modulus of the tangential component in the orientations ${\boldsymbol{e}}_\phi $ and ${\boldsymbol{e}}_\theta $, respectively, of the electric far-field pattern measured on the unit sphere and generated by infinitely many sets of superpositions of two electromagnetic plane waves with different directions and polarizations. Our proof is mainly based on Rellich’s lemma and the Stratton–Chu formula for radiating solutions to the Maxwell equations.

Evanescent plane waves and the far field: Resolution of a controversy

2000 ◽  
Vol 47 (4) ◽  
pp. 759-763 ◽  
Author(s):  
Akhlesh Lakhtakia ◽  
Werner S. Weiglhofer
Keyword(s):  
Plane Waves ◽  
Far Field
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