scholarly journals A Subspace-Based Compensation Method for the Mutual Coupling in Concentric Circular Ring Arrays for Near-Field Source Localisation

2012 ◽  
Vol 2012 ◽  
pp. 1-13 ◽  
Author(s):  
Mohammed Jainul Abedin ◽  
Ananda Sanagavarapu Mohan
Keyword(s):  
Parameter Estimation ◽  
Mutual Coupling ◽  
Near Field ◽  
Three Dimensional ◽  
Super Resolution ◽  
Circular Ring ◽  
Dipole Antennas ◽  
Field Source ◽  
Full Wave ◽  
Compensation Approach

We propose a technique for compensating the effect of mutual coupling on parameter estimation that is suitable with any subspace-based super-resolution algorithms. A Concentric circular ring array (CCRA) formed using thin dipole antennas in the receiving mode is employed to estimate the parameters of electromagnetic sources located in the radiating near field of the array. A CCRA geometry that obtains a lowest Cramer-Rao lower bound (CRLB) in the presence of array mutual coupling is chosen for investigation. The mutual coupling among antenna elements of the array would affect the orthogonality of subspaces when MUSIC or ESPRIT algorithms are used for parameter estimation. The proposed method obtains a compensation matrix that restores the orthogonality between the subspaces there by improving the accuracy of estimation. To avoid three-dimensional searches, the range parameter is estimated using a cross-correlation-based method. Numerical simulation using a full-wave electromagnetic (EM) solver is employed to demonstrate the effectiveness of the proposed compensation approach.

Multifunctional metasurfaces integrating near-field display and 3D holography

2021 ◽  
Author(s):  
Wenjuan Du ◽  
Zhilang Lou ◽  
Xuesong Chen ◽  
Long Chen ◽  
Dongliang Tang
Keyword(s):  
Near Field ◽  
Three Dimensional ◽  
Optical Field ◽  
Amplitude Control ◽  
3D Images ◽  
Full Wave ◽  
Complex Functions ◽  
Channel Information ◽  
Amplitude Modulator ◽  
Optical Applications

Abstract Metasurfaces have versatile manipulation capabilities in the optical field and provide the possibility of building a compact optical device with various complex functions. They have been regarded as ideal candidates to construct a miniaturized optical system with high density and multi-channel information. In this work, reflective all-metallic multifunctional metasurfaces consisting of aluminum nanorods are designed by simultaneously realizing the near-filed display and three-dimensional (3D) holography. Specifically, in the proposed design, each nanorod acts as a complex amplitude modulator to provide continuous amplitude control and binary phase control. By carefully optimizing the orientations of nanorods, a multifunctional metasurface can be designed to display a near-field grayscale pattern and far-field 3D images simultaneously. Numerical results by a full-wave simulation validate the good performance of the proposed design. The proposed method could provide more degree of freedom to designs of lightweight devices, which could be employed in optical applications, such as the virtual or augmented reality display and anti-counterfeit technology.

scholarly journals Three-Dimensional Super-Resolution Morphology by Near-Field Assisted White-Light Interferometry

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Feifei Wang ◽  
Lianqing Liu ◽  
Peng Yu ◽  
Zhu Liu ◽  
Haibo Yu ◽  
...  
Keyword(s):  
White Light ◽  
Near Field ◽  
Three Dimensional ◽  
Super Resolution ◽  
White Light Interferometry

scholarly journals Ultrabroadband 3D invisibility with fast-light cloaks

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
K. L. Tsakmakidis ◽  
O. Reshef ◽  
E. Almpanis ◽  
G. P. Zouros ◽  
E. Mohammadi ◽  
...  
Keyword(s):  
Near Field ◽  
Three Dimensional ◽  
Visible Spectrum ◽  
Three Dimensions ◽  
Microscopy Imaging ◽  
The Road ◽  
Full Wave ◽  
Invisibility Cloak ◽  
Scanning Optical Microscopy ◽  
Fast Light

Abstract An invisibility cloak should completely hide an object from an observer, ideally across the visible spectrum and for all angles of incidence and polarizations of light, in three dimensions. However, until now, all such devices have been limited to either small bandwidths or have disregarded the phase of the impinging wave or worked only along specific directions. Here, we show that these seemingly fundamental restrictions can be lifted by using cloaks made of fast-light media, termed tachyonic cloaks, where the wave group velocity is larger than the speed of light in vacuum. On the basis of exact analytic calculations and full-wave causal simulations, we demonstrate three-dimensional cloaking that cannot be detected even interferometrically across the entire visible regime. Our results open the road for ultrabroadband invisibility of large objects, with direct implications for stealth and information technology, non-disturbing sensors, near-field scanning optical microscopy imaging, and superluminal propagation.

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