Diffraction of electromagnetic waves in Schwarzschild's space-time

1980 ◽  
Vol 71 (1) ◽  
pp. 171-194 ◽  
Author(s):  
Thomas Elster
Keyword(s):  
Electromagnetic Waves ◽  
Space Time

Bateman electromagnetic waves

1984 ◽  
Vol 396 (1810) ◽  
pp. 199-204 ◽  
Keyword(s):  
Electromagnetic Wave ◽  
Electromagnetic Waves ◽  
Plane Electromagnetic Wave ◽  
Flat Space ◽  
Space Time

It is proved that in flat space-time every electromagnetic wave is a Bateman wave and, as a corollary, that every plane electromagnetic wave is a Synge wave.

scholarly journals Quanton Fields: Evolution and Degrees of Freedom

2021 ◽  
Author(s):  
AYMAN KASSEM MOHAMMED
Keyword(s):  
Electromagnetic Waves ◽  
Maxwell Equations ◽  
Degrees Of Freedom ◽  
Space Time ◽  
The Third ◽  
Space And Time ◽  
The Subject ◽  
Physical Phenomena

The concept of space time had been the subject of debate for so long, here another version will be discussed in the form of space and time fields where a new concept of energy constraining can explain the interactions between those fields. This model comes in three parts : energy constraining , where the evolution of the quanton and its different transitions are discussed, the second part , energy fields, their degrees of freedom and the third part electromagnetic waves as relativistic quantons and the generic form of Maxwell equations in terms of space and time fields. This work shows that the origin many of the physical phenomena can be traced back to the quanton based world .

scholarly journals Design of In-phase and Quadrature Two Paths Space-Time-Modulated Metasurfaces

2021 ◽  
Author(s):  
Mengmeng Li ◽  
Mengmeng Li ◽  
Filiberto Bilotti
Keyword(s):  
Frequency Domain ◽  
Electromagnetic Waves ◽  
Specular Reflection ◽  
Small Dimension ◽  
Space Time ◽  
Start Time ◽  
First Order ◽  
Unit Cells ◽  
Potential Applications ◽  
Space Frequency

<p>Space-time-modulated metasurfaces can manipulate electromagnetic waves in space and frequency domain simultaneously. In this paper, an analytical design of space-time- modulated metasurfaces with modulation elements composed of two paths, In-phase (I) and Quadrature (Q), is proposed. The model is derived analytically, <a>the space/frequency domain</a> manipulations are achieved by designing the dimension and time sequence of I and Q paths.<a> In the specular reflection direction, an objective frequency shift of the reflected first order harmonic can be obtained. While, in other directions, the opposite first order harmonic can be easily controlled by changing the dimension of I/Q paths and the objective first order harmonic remains unchanged.</a> Furthermore, with a small dimension of I/Q paths, the first order harmonic can be used for beam scanning by pre-designing the start time of the modulation element. To realize the space-time-modulated metasurface with the required periodically time-varying responses, 2-bit unit-cells loaded with dynamically switchable pin diodes are employed as I/Q modulation. Both analytical and numerical results demonstrate that space and frequency domain manipulations of the reflected fields by the first order harmonics can be simultaneously obtained. The proposed designs have potential applications in wireless communications, radar camouflaging, and cloaking.</p>

scholarly journals Space-Time-Coding Digital Metasurfaces: Principles and Applications

Research ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-25
Author(s):  
Lei Zhang ◽  
Tie Jun Cui
Keyword(s):  
Electromagnetic Waves ◽  
Space Time ◽  
Research Field ◽  
Future Directions ◽  
Space Time Coding ◽  
Research Fields ◽  
Nonreciprocal Effect ◽  
Comprehensive Survey ◽  
Spatial Domains ◽  
Time Coding

Space-time-modulated metastructures characterized by spatiotemporally varying properties have recently attracted great interest and become one of the most fascinating and promising research fields. In the meantime, space-time-coding digital metasurfaces with inherently programmable natures emerge as powerful and versatile platforms for implementing the spatiotemporal modulations, which have been successfully realized and used to manipulate the electromagnetic waves in both the spectral and spatial domains. In this article, we systematically introduce the general concepts and working principles of space-time-coding digital metasurfaces and provide a comprehensive survey of recent advances and representative applications in this field. Specifically, we illustrate the examples of complicated wave manipulations, including harmonic beam control and programmable nonreciprocal effect. The fascinating strategy of space-time-coding opens the door to exciting scenarios for information systems, with abundant applications ranging from wireless communications to imaging and radars. We summarize this review by presenting the perspectives on the existing challenges and future directions in this fast-growing research field.

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