scholarly journals Examination of Far-Field Mathematical Absorber Reflection Suppression through Computational Electromagnetic Simulation

2012 ◽  
Vol 2012 ◽  
pp. 1-10 ◽  
Author(s):  
S. F. Gregson ◽  
A. C. Newell ◽  
G. E. Hindman
Keyword(s):  
Near Field ◽  
Three Dimensional ◽  
Test System ◽  
General Purpose ◽  
Far Field ◽  
Antenna Measurement ◽  
Compact Antenna ◽  
Measurement Systems ◽  
Electromagnetic Model ◽  
Spherical Antenna

The mathematical absorber reflection suppression (MARS) technique has been used to identify and then suppress the effects of spurious scattering within spherical, cylindrical, and planar near-field antenna measurement systems, compact antenna test ranges (CATRs), and far-field measurement facilities for some time now. The recent development of a general-purpose three-dimensional computational electromagnetic model of a spherical antenna test system has enabled the MARS measurement and postprocessing technique to be further investigated. This paper provides an overview of the far-field MARS technique and presents an introduction to the computational electromagnetic range model. Preliminary results of computational electromagnetic range simulations that replicate typical MARS measurement configurations are presented and discussed which, for the first time, confirm through simulation many of the observations that have previously been noted using purely empirical techniques.

Multiband compact antenna for near‐field and far‐field RFID and wireless portable applications

2016 ◽  
Vol 11 (4) ◽  
pp. 535-541 ◽  
Author(s):  
Parisa Forouzannezhad ◽  
Amir Jafargholi ◽  
Alireza Jahanbakhshi
Keyword(s):  
Near Field ◽  
Far Field ◽  
Compact Antenna

scholarly journals An Innovative Direct NF-FF Transformation Technique with Helicoidal Scanning

2012 ◽  
Vol 2012 ◽  
pp. 1-9 ◽  
Author(s):  
Francesco D’Agostino ◽  
Flaminio Ferrara ◽  
Claudio Gennarelli ◽  
Rocco Guerriero ◽  
Massimo Migliozzi
Keyword(s):  
Electromagnetic Fields ◽  
Field Data ◽  
Near Field ◽  
Transverse Dimension ◽  
Computational Effort ◽  
Far Field ◽  
Transformation Technique ◽  
Spherical Antenna ◽  
Field Transformation ◽  
Mechanical Scanning

A direct near-field-far-field transformation with helicoidal scanning is developed. It is based on the nonredundant sampling representation of electromagnetic fields and uses a spherical antenna modelling to determine the number of helix turns. Moreover, the number of voltage samples on each of them is fixed by the maximum transverse dimension of the antenna, both to simplify the mechanical scanning and to reduce the computational effort. This technique allows the evaluation of the antenna far field directly from a minimum set of near-field data without interpolating them. Although the number of near-field data employed by the developed technique is slightly increased with respect to that required by rigorously applying the nonredundant sampling representation on the helix, it is still remarkably smaller than that needed by the standard near-field-far-field transformation with cylindrical scanning. The effectiveness of the technique is assessed by numerical and experimental results.

Theoretical and experimental studies of three-dimensional wavemaking in narrow tanks, including nonlinear phenomena near resonance

1994 ◽  
Vol 276 ◽  
pp. 211-232 ◽  
Author(s):  
Yitao Yao ◽  
Marshall P. Tulin ◽  
Ali R. Kolaini
Keyword(s):  
Nonlinear Wave ◽  
Near Field ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Analytical Techniques ◽  
Nonlinear Phenomena ◽  
Far Field ◽  
Wave Groups ◽  
Near Resonance ◽  
Matching Techniques

In view of several practical ramifications of this problem, computational-analytical techniques for calculating waves induced by heaving arbitrary bodies in narrow tanks have been developed, including nonlinear wave groups produced near tank resonance. These feature computational near-field solutions matched with appropriate far-field solutions. In the linear case, the far field is provided by linear mode superposition. In the nonlinear case, the far field is described by a suitable nonlinear evolution equation of the cubic Schrödinger type. Matching techniques were developed. Calculations were successfully carried out and the results confirm the important effect of tank walls on added mass and damping.Results of computations have been compared with some data obtained with a conical wavemaker in a narrow tank. Pronounced nonlinear wave groups were obtained near resonance, and these are well reproduced in some detail by the nonlinear theory and computations, without considering any effects of dissipation.The related problem of resonant wave groups produced by a segmented paddle wavemaker has also been treated by analysis and subject to computation, with good general agreement with past experiments. The technique features matching near- and far-field computations using energy considerations.

scholarly journals Roughness effect on the efficiency of dimer antenna based biosensor

2012 ◽  
Vol 1 (2) ◽  
pp. 41 ◽  
Author(s):  
D. Barchiesi ◽  
S. Kessentini
Keyword(s):  
Surface Roughness ◽  
Near Field ◽  
Three Dimensional ◽  
Biological Molecules ◽  
Far Field ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Roughness Effect ◽  
Highly Sensitive ◽  
Local Plasmon

The fabrication process of nanodevices is continually improved. However, most of the nanodevices, such as biosensors present rough surfaces with mean roughness of some nanometers even if the deposition rate of material is more controlled. The effect of roughness on performance of biosensors was fully addressed for plane biosensors and gratings, but rarely addressed for biosensors based on Local Plasmon Resonance. The purpose of this paper is to evaluate numerically the influence of nanometric roughness on the efficiency of a dimer nano-biosensor (two levels of roughness are considered). Therefore, we propose a general numerical method, that can be applied to any other nanometric shape, to take into account the roughness in a three dimensional model. The study focuses on both the far-field, which corresponds to the experimental detected data, and the near-field, responsible for exciting and then detecting biological molecules. The results suggest that the biosensor efficiency is highly sensitive to the surface roughness. The roughness can produce important shifts of the extinction efficiency peak and a decrease of its amplitude resulting from changes in the distribution of near-field and absorbed electric field intensities.

scholarly journals Error Analysis and Simulator in Cylindrical Near-Field Antenna Measurement Systems

10.5772/8735 ◽  
2010 ◽  
Author(s):  
Burgos Sara ◽  
Sierra-Castaner Manuel ◽  
Martin Fernando ◽  
Cano Francisco ◽  
Besada Jose
Keyword(s):  
Error Analysis ◽  
Near Field ◽  
Antenna Measurement ◽  
Measurement Systems
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