dipole radiation
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Author(s):  
Jing-chun Yan ◽  
Shi-qian Zhang ◽  
Yong Zhang ◽  
Yu-lin Wang ◽  
Cheng-ping Huang

Abstract Planar split-ring resonators (SRRs) with broken symmetry, excited by the electric field of incident wave, have been widely used to realize the high-Q resonance. In this paper, we report by theory and experiment an alternative scheme to induce the SRR-based high-Q resonance. The proposed scheme utilizes a two-dimensional array of vertical SRRs with vertical air gaps, which enables the excitation of narrow resonance with magnetic field and strong enhancement of local electromagnetic fields. The working mechanism correlates with the strong directional dependence of the dipole radiation (i.e., the elimination of electric-dipole radiation of the SRRs in the propagation direction), rather than the destructive interference due to the structural symmetry breaking. The dependence of Q factor on the structural parameters has also been studied theoretically, suggesting that a Q factor more than 2000 can be achieved. The results may be useful for designing narrow-band filters and sensors in the microwave or THz regime.


2021 ◽  
Vol 921 (1) ◽  
pp. L1
Author(s):  
Le Zou ◽  
Tian-Ci Zheng ◽  
Xing Yang ◽  
Hai-ming Zhang ◽  
Xiao-Yan Li ◽  
...  

Author(s):  
Xiao-Bo Zhang ◽  
Xin Qiao ◽  
Li-Hong Cheng ◽  
Ai-Xia Zhang ◽  
Ju-Kui Xue

2021 ◽  
Vol 2021 (6) ◽  
Author(s):  
Mustafa A. Amin ◽  
Andrew J. Long ◽  
Zong-Gang Mou ◽  
Paul M. Saffin

Abstract We investigate the production of photons from coherently oscillating, spatially localized clumps of axionic fields (oscillons and axion stars) in the presence of external electromagnetic fields. We delineate different qualitative behaviour of the photon luminosity in terms of an effective dimensionless coupling parameter constructed out of the axion-photon coupling, and field amplitude, oscillation frequency and radius of the axion star. For small values of this dimensionless coupling, we provide a general analytic formula for the dipole radiation field and the photon luminosity per solid angle, including a strong dependence on the radius of the configuration. For moderate to large coupling, we report on a non-monotonic behavior of the luminosity with the coupling strength in the presence of external magnetic fields. After an initial rise in luminosity with the coupling strength, we see a suppression (by an order of magnitude or more compared to the dipole radiation approximation) at moderately large coupling. At sufficiently large coupling, we find a transition to a regime of exponential growth of the luminosity due to parametric resonance. We carry out 3+1 dimensional lattice simulations of axion electrodynamics, at small and large coupling, including non-perturbative effects of parametric resonance as well as backreaction effects when necessary. We also discuss medium (plasma) effects that lead to resonant axion to photon conversion, relevance of the coherence of the soliton, and implications of our results in astrophysical and cosmological settings.


2021 ◽  
Vol 57 (3) ◽  
pp. 50-61
Author(s):  
A. Grigoriev ◽  
◽  
S. Shiryaeva ◽  
N. Kolbneva ◽  
◽  
...  

An asymptotic calculation of a dipole electromagnetic radiation of an uncharged conductive drop oscillating with a finite amplitude in an external electrostatic field to within the second order of smallness inclusive on the relation of the amplitude of oscillations to the radius of an initial drop is carried out. It is shown that the first mode of oscillations is excited in the calculation of the second order of smallness. As a result, the centers of the induced charges with different signs will synchronously oscillate, and the drop will radiate electromagnetic waves of dipolar type, forming the nonlinear correction to intensity of dipole radiation of the first order of smallness. An assessment of the intensity of electromagnetic radiation of this correction and of the width of a strip of frequencies depending on the size of a drop and the strength of an external electrostatic field is carried out.


2021 ◽  
Vol 489 ◽  
pp. 126867
Author(s):  
Henk F. Arnoldus
Keyword(s):  

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