scholarly journals A Generalized Approach for Computation of Near Field Radiation Pattern of an Antenna

2014 ◽  
Vol 2014 ◽  
pp. 1-18
Author(s):  
Preetham Shankpal ◽  
Varun Arur ◽  
Govind Kadambi ◽  
James Shuttleworth
Keyword(s):  
Radiation Pattern ◽  
Near Field ◽  
Circular Waveguide ◽  
Field Analysis ◽  
Far Field ◽  
Magnetic Dipoles ◽  
Underlying Principle ◽  
Field Radiation ◽  
Conical Horn

A generalized procedure in the form of an analytical formulation for the determination of radiation pattern of an antenna at any arbitrary distance which covers the near field as well as far field is presented in this paper. With the prior knowledge of either the current or field distribution on the radiating aperture, the proposed near field analysis is generic and can be applied for wide variety of antenna elements. The underlying principle of the generalized procedure is tantamount to considering the radiating aperture as an array of point electric and magnetic dipoles. The validity and novelty of the proposed new approach have been substantiated considering an open ended circular cylindrical waveguide and a conical horn as case studies and treating the far field as a special case of near field with pertinent distance criterion. The effect of change in the distance of observation ranging from reactive near field to far field on the radiation patterns of these antennas has also been discussed. The simulation studies reveal that the depicted normalized phase patterns of both the circular waveguide and conical horn follow the changes in the profile of the corresponding amplitude patterns.

scholarly journals Far-Field Reconstruction from Transient Near-Field Measurement Using Cylindrical Modal Development

2009 ◽  
Vol 2009 ◽  
pp. 1-7 ◽  
Author(s):  
R. Rammal ◽  
M. Lalande ◽  
E. Martinod ◽  
N. Feix ◽  
M. Jouvet ◽  
...  
Keyword(s):  
Field Measurement ◽  
Near Field ◽  
Accurate Determination ◽  
Ultra Wideband ◽  
Far Field ◽  
Field Radiation ◽  
Measurement Base ◽  
Large Frequency ◽  
Near Field Measurement

The aim of this work is to get far field radiation patterns for any radiating source from transient acquisition, in a large frequency range. An outdoor transient Ultra-Wideband near-field measurement base will be installed, a single time pulse radiated by the source will cover the desired spectrum, and the accurate determination of far field radiations will be accomplished by means of cylindrical waves' modal development. This method uses simplified test equipments, easy to be installed, and it reduces measurement costs.

scholarly journals Manipulating Optical Scattering of Quasi-BIC in Dielectric Metasurface with Off-Center Hole

Nanomaterials ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 54
Author(s):  
Chaobiao Zhou ◽  
Tianyao Pu ◽  
Jing Huang ◽  
Menghui Fan ◽  
Lujun Huang
Keyword(s):  
Radiation Pattern ◽  
Bound States ◽  
Near Field ◽  
Research Work ◽  
Electric Quadrupole ◽  
Asymmetric Structure ◽  
Far Field ◽  
Q Factor ◽  
Field Radiation ◽  
The Continuum

Bound states in the continuum (BICs) correspond to a particular leaky mode with an infinitely large quality-factor (Q-factor) located within the continuum spectrum. To date, most of the research work reported focuses on the BIC-enhanced light matter interaction due to its extreme near-field confinement. Little attention has been paid to the scattering properties of the BIC mode. In this work, we numerically study the far-field radiation manipulation of BICs by exploring multipole interference. By simply breaking the symmetry of the silicon metasurface, an ideal BIC is converted to a quasi-BIC with a finite Q-factor, which is manifested by the Fano resonance in the transmission spectrum. We found that both the intensity and directionality of the far-field radiation pattern can not only be tuned by the asymmetric parameters but can also experience huge changes around the resonance. Even for the same structure, two quasi-BICs show a different radiation pattern evolution when the asymmetric structure parameter d increases. It can be found that far-field radiation from one BIC evolves from electric-quadrupole-dominant radiation to toroidal-dipole-dominant radiation, whereas the other one shows electric-dipole-like radiation due to the interference of the magnetic dipole and electric quadrupole with the increasing asymmetric parameters. The result may find applications in high-directionality nonlinear optical devices and semiconductor lasers by using a quasi-BIC-based metasurface.

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