scholarly journals On the applicability of the spherical wave expansion with a single origin for near-field acoustical holography

2009 ◽  
Vol 125 (3) ◽  
pp. 1529-1537 ◽  
Author(s):  
Jesper Gomes ◽  
Jørgen Hald ◽  
Peter Juhl ◽  
Finn Jacobsen
Keyword(s):  
Near Field ◽  
Spherical Wave ◽  
Single Origin ◽  
Wave Expansion ◽  
Spherical Wave Expansion ◽  
Acoustical Holography

scholarly journals Near-Field to Far-Field RCS Prediction on Arbitrary Scanning Surfaces Based on Spherical Wave Expansion

Sensors ◽  
2020 ◽  
Vol 20 (24) ◽  
pp. 7199
Author(s):  
Woobin Kim ◽  
Hyeong-Rae Im ◽  
Yeong-Hoon Noh ◽  
Ic-Pyo Hong ◽  
Hyun-Sung Tae ◽  
...  
Keyword(s):  
Near Field ◽  
Linear Equations ◽  
Spherical Wave ◽  
Scattered Wave ◽  
Far Field ◽  
Field Region ◽  
System Of Linear Equations ◽  
Wave Expansion ◽  
Field Transformation ◽  
Spherical Wave Expansion

Near-field to far-field transformation (NFFFT) is a frequently-used method in antenna and radar cross section (RCS) measurements for various applications. For weapon systems, most measurements are captured in the near-field area in an anechoic chamber, considering the security requirements for the design process and high spatial costs of far-field measurements. As the theoretical RCS value is the power ratio of the scattered wave to the incident wave in the far-field region, a scattered wave measured in the near-field region needs to be converted into field values in the far-field region. Therefore, this paper proposes a near-field to far-field transformation algorithm based on spherical wave expansion for application in near-field RCS measurement systems. If the distance and angular coordinates of each measurement point are known, the spherical wave functions in an orthogonal relationship can be calculated. If each weight is assumed to be unknown, a system of linear equations as numerous as the number of samples measured in the near electric field can be generated. In this system of linear equations, each weight value can be calculated using the iterative least squares QR-factorization method. Based on this theory, the validity of the proposed NFFFT is verified for several scatterer types, frequencies and measurement distances.

scholarly journals Efficient estimation of EMI from stacked radiation sources by combining their spherical wave expansion coefficients

2020 ◽  
Vol 14 (13) ◽  
pp. 1504-1513
Author(s):  
Carlo Olivieri ◽  
Francesco de Paulis ◽  
Antonio Orlandi ◽  
Federico Centola ◽  
Gregory Sizikov
Keyword(s):  
Spherical Wave ◽  
Efficient Estimation ◽  
Wave Expansion ◽  
Radiation Sources ◽  
Expansion Coefficients ◽  
Spherical Wave Expansion
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