A generalized reciprocity theorem for electromagnetic optics in the moving media

1980 ◽  
Author(s):  
Hideya Gamo
Keyword(s):  
Reciprocity Theorem ◽  
Electromagnetic Optics ◽  
Moving Media

Application of the reciprocity theorem for the evaluation of vibrations generated by moving loads

2020 ◽  
pp. 33-40
Author(s):  
Nguyen Tron Tam ◽  
◽  
E.N. Kurbatsky ◽  
Nguyen Anh Tuan ◽  
◽  
...  
Keyword(s):  
Reciprocity Theorem ◽  
Moving Loads

An efficient hybrid method for analyzing the coupling response of microstrip antenna system

2021 ◽  
pp. 1-14
Author(s):  
Xiao Hu ◽  
Yang Qiu ◽  
Qing-Lin Xu ◽  
Jin Tian
Keyword(s):  
Hybrid Method ◽  
Microstrip Antenna ◽  
Fdtd Method ◽  
Antenna System ◽  
Reciprocity Theorem ◽  
Thin Wire ◽  
Equivalent Source ◽  
Impedance Model ◽  
Antenna Coupling ◽  
Lorentz Reciprocity Theorem

This paper presents an efficient hybrid method consisting of Lorentz reciprocity theorem, finite-difference-time-domain (FDTD) method, thin wire model, transmission line (TL) equations and transfer impedance model, which can be utilized to analyze the system-level transient responses of the microstrip antenna system with antenna, metallic enclosures, braided shielded cable, and lumped element, when illuminated by an external electromagnetic pulse (EMP). In order to avoid over-fine mesh generation and repeated modeling of the antenna in multiple simulations, Lorentz reciprocity theorem is employed to extract an equivalent source model of antenna coupling, thereby improving the computational efficiency. Then, the transfer impedance model and thin wire model are incorporated into the FDTD-TL method efficiently to deal with the back-door coupling through the shielding layer of feeding coaxial cable. Finally, the hybrid FDTD method combined with the extracted equivalent source of antenna coupling is utilized to solve the coupling responses of the whole antenna system. The results of numerical simulation are verified by comparing with the simulation results of CST CS. Then, considering the influence of different incident conditions of external EMP, the characteristics of the coupling response of the system are analyzed. The obtained coupling response information demonstrate that the proposed method is available for further designing electromagnetic protection of the inner circuits of the microstrip antenna system against the impact of external EMP.

scholarly journals Tutorial on seismic interferometry: Part 2 — Underlying theory and new advances

Geophysics ◽  
2010 ◽  
Vol 75 (5) ◽  
pp. 75A211-75A227 ◽  
Author(s):  
Kees Wapenaar ◽  
Evert Slob ◽  
Roel Snieder ◽  
Andrew Curtis
Keyword(s):  
Green’S Function ◽  
Green's Function ◽  
Seismic Interferometry ◽  
Virtual Source ◽  
Bending Waves ◽  
Complex Source ◽  
Recent Developments ◽  
Diffusion Phenomena ◽  
Quantum Mechanical Scattering ◽  
Moving Media

In the 1990s, the method of time-reversed acoustics was developed. This method exploits the fact that the acoustic wave equation for a lossless medium is invariant for time reversal. When ultrasonic responses recorded by piezoelectric transducers are reversed in time and fed simultaneously as source signals to the transducers, they focus at the position of the original source, even when the medium is very complex. In seismic interferometry the time-reversed responses are not physically sent into the earth, but they are convolved with other measured responses. The effect is essentially the same: The time-reversed signals focus and create a virtual source which radiates waves into the medium that are subsequently recorded by receivers. A mathematical derivation, based on reciprocity theory, formalizes this principle: The crosscorrelation of responses at two receivers, integrated over differ-ent sources, gives the Green’s function emitted by a virtual source at the position of one of the receivers and observed by the other receiver. This Green’s function representation for seismic interferometry is based on the assumption that the medium is lossless and nonmoving. Recent developments, circumventing these assumptions, include interferometric representations for attenuating and/or moving media, as well as unified representations for waves and diffusion phenomena, bending waves, quantum mechanical scattering, potential fields, elastodynamic, electromagnetic, poroelastic, and electroseismic waves. Significant improvements in the quality of the retrieved Green’s functions have been obtained with interferometry by deconvolution. A trace-by-trace deconvolution process compensates for complex source functions and the attenuation of the medium. Interferometry by multidimensional deconvolution also compensates for the effects of one-sided and/or irregular illumination.

Neutron Transport in Moving Media

1979 ◽  
Vol 36 (2) ◽  
pp. 230-262 ◽  
Author(s):  
H. L. Wilson ◽  
W. H. Scott, Jr. ◽  
G C. Pomraning
Keyword(s):  
Neutron Transport ◽  
Moving Media
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