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"electromagnetic wave"
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The science of light waves
\"This engaging book describes the properties of light waves, how they move, and the way our eyes receive them. Readers will learn that we see an object when light reflects from its surface and into the eye. A link to interactive activities online plus an activity in the book allow readers to create models that explore how to redirect and block the path a light wave travels.\"-- Provided by publisher.
Book
A Novel Strategy in Electromagnetic Wave Absorbing and Shielding Materials Design: Multi‐Responsive Field Effect
The electromagnetic (EM) devices have been widely used in communication, electrical engineering, and medical care. However, EM device is a double‐edged sword for its convenience is followed by signal pollution and radiation. Electromagnetic interference (EMI) combat has brought lots of attention to researchers in this field. Researchers have made great efforts in developing electromagnetic wave absorbing and shielding (EMAS) materials to reduce EM wave power density to solve the above problem. However, the great majority of reported EMAS materials are powders and coatings, which possess merely EMAS property. Modern practical application has abundant multiple scenes, including high temperature, intense light, water flow, etc. Under the circumstances, EMAS materials should be functionalized with outstanding tunable absorption bands. Based on field theory in physics, multiexternal fields‐responsive materials are an effective method to deal with the above urgently unsolved problem. Thus, herein, different external field‐responsive materials, including temperature, light, space–time, electrical, wind, density, and flow fields, are focused on. Various action mechanisms, materials synthesis methods, and different macrostructures are summarized in detail. Meanwhile, the developing trends of novel external field‐responsive materials are also discussed in order. Finally, the challenges of designing new type of EMAS devices are mentioned. The current multifunctional electromagnetic wave absorbing and shielding (EMAS) materials are reviewed. An external field‐responsive strategy is proposed to enrich application scenes, including temperature field, light field, space–time field, electrical field, wind field, density field, and flow field. Action mechanisms and EMAS performance improvements are discussed and concluded.
Journal Article
Anechoic and Reverberation Chambers
<p><b>A Comprehensive Review of the Recent Advances in Anechoic Chamber and Reverberation Chamber Designs and Measurements</b></p> <p><i>Anechoic and Reverberation Chambers</i> is a guide to the latest systematic solutions for designing anechoic chambers that rely on state-of-the-art computational electromagnetic algorithms. This essential resource contains a theoretical and practical understanding for electromagnetic compatibility and antenna testing. The solutions outlined optimise chamber performance in the structure, absorber layout and antenna positions whilst minimising the overall cost. The anechoic chamber designs are verified by measurement results from Microwave Vision Group that validate the accuracy of the solution.</p> <p><i>Anechoic and Reverberation Chambers</i> fills an important gap in the literature by providing a comprehensive reference to electromagnetic measurements, applications and over-the-air tests inside chambers. The expert contributors offer a summary of the latest developments in anechoic and reverberation chambers to help scientists and engineers apply the most recent technologies in the field. In addition, the book contains a comparison between reverberation and anechoic chambers and identifies their strengths and weaknesses. This important resource:</p> <ul> <li>Provides a systematic solution for anechoic chamber design by using state-of-the-art computational electromagnetic algorithms</li> <li>Examines both types of chamber in use, comparing and contrasting the advantages and disadvantages of each</li> <li>Reviews typical over-the-air measurements and new applications in reverberation chambers</li> <li>Offers a timely and complete reference written by authors working at the cutting edge of the technology</li> <li>Contains helpful illustrations, photographs, practical examples and comparisons between measurements and simulations</li> </ul> <p>Written for both academics and industrial engineers and designers, <i>Anechoic and Reverberation Chambers</i> explores the most recent advances in anechoic chamber and reverberation chamber designs and measurements.</p>
eBook
Applied Frequency-Domain Electromagnetics
Understanding electromagnetic wave theory is pivotal in the design of antennas, microwave circuits, radars, and imaging systems. Researchers behind technology advances in these and other areas need to understand both the classical theory of electromagnetics as well as modern and emerging techniques of solving Maxwell's equations. To this end, the book provides a graduate-level treatment of selected analytical and computational methods. The analytical methods include the separation of variables, perturbation theory, Green's functions, geometrical optics, the geometrical theory of diffraction, physical optics, and the physical theory of diffraction. The numerical techniques include mode matching, the method of moments, and the finite element method. The analytical methods provide physical insights that are valuable in the design process and the invention of new devices. The numerical methods are more capable of treating general and complex structures. Together, they form a basis for modern electromagnetic design. The level of presentation allows the reader to immediately begin applying the methods to some problems of moderate complexity. It also provides explanations of the underlying theories so that their capabilities and limitations can be understood.
eBook
Approximate Analytic Formulas for Backscattering/Extinction Coefficients and Its Application to Lidar System
We present approximate analytical solutions, based on anomalous diffraction theory and the modified Rayleigh‐Debye approach for the backscattering/extinction coefficients and apply them to the elastic lidar equation. Figure shows a log polar plot of the angular dependence of the Mie scattering intensityfor a large particle size parameter, which resembles a flatfish facing the backscattering direction and provides a lidar signal.
Journal Article
Oblique Electromagnetic Wave Incidence on a Plane Resonator Consisting of Two Dielectric Layers with Strip Conductor Subwavelength Gratings at Their Interfaces
The parameters of a resonator consisting of two dielectric plates with gratings of strip conductors between the layers in the form of squares, and on the outer surfaces in the form of square meshes having the same subwavelength period, have been determined. The quality (Q) factor of the resonator, which has been measured at the normal wave incidence, is determined by the ratio of the widths of the internal and external conductors. Using electrodynamic analysis of a 3D resonator model, the propagation of plane linearly polarized electromagnetic waves when their angle of incidence φ deviates from the normal to the plane of the layered structure has been studied. It is found that for the parallel polarization of the wave, the Q factor of the observed half-wave resonance with increasing φ first drops to a minimum when approaching the Brewster angle, and then increases as φ → 90°. In the case of the perpendicular polarization of the wave, the Q factor of the half-wave resonance gradually increases with increasing φ, approaching the maximum value at φ → 90°.
Journal Article
Verification of the Radio Wave Absorption Effect in the Millimeter Wave Band of SWCNTs and Conventional Carbon-Based Materials
Using a sample coated with three types of carbon-based paints, namely single-wall carbon nanotube (SWCNTs), carbon black, and graphite, the amount of radio wave absorption for each was measured. SWCNTs proved to have the superior radio wave absorption effect in the millimeter band. Considering the change in the amount of radio wave absorption depending on the coating amount, three different coating thicknesses were prepared for each test material. The measurement frequency was set to two frequency bands of 28 GHz and 75 GHz, and the measurement method was carried out based on Japanese Industrial Standard (JIS) R1679 “Radio wave absorption characteristic measurement method in the millimeter wave band of the radio wave absorber.” As for the amount of radio wave absorption in the 28 GHz band, a maximum amount of radio wave absorption of about 6 dB was obtained when 35 m of CNT spray paint was applied. It was confirmed that the carbon black paint came to about 60% that of the SWCNT, and the graphite paint did not obtain much radio wave absorption even when the coating thickness was changed. Furthermore, even in the 75 GHz band, the radio wave absorption was about 7 dB when 16 μm of CNT spray paint was applied, showing the maximum value. Within these experimental results, the CNT spray paint has a higher amount of radio wave absorption in the millimeter wave band than paints using general carbon materials. Its effectiveness could be confirmed even with a very thin coating thickness of 35 μm or less. It was also confirmed that even with the same paint, the radio wave absorption effect changes depending on the difference in coating thickness and the condition of the coated surface.
Journal Article
Experimental validation of nonreciprocal metasurface using simple structure
The non‐reciprocity of electromagnetic waves is a technology garnering significant attention for its applications in electromagnetic security and the mitigation of electromagnetic interference, serving to control radio waves in space. This article outlines a comprehensive design approach for a novel non‐reciprocal structure that integrates ferrite and metal patches. Additionally, it presents experimental results utilizing two types of ferrites. The experiments demonstrated the attainment of 15 dB isolation at both 6.25 GHz and 6.5 GHz. In this article, a non‐reciprocal, radio band one‐way mirror is realized using magnetic material array.
Journal Article
The Behaviours of Electromagnetic Wave Propagation in Carbon Nanotube-Layered Nanocomposites
This comprehensive study delves into the intricate behaviours of electromagnetic (EM) wave propagation in a sophisticated, multilayered nanocomposite structure. The structure comprises four precisely engineered layers, each meticulously crafted from carbon nanotube (CNT) fibres arranged at specific angles and directions. These intricate arrangements not only define the structural integrity of the composite but also play a pivotal role in determining the material properties of each layer. Remarkably, when the layers are meticulously arranged at angles of [0°/90°/90°/0°] with respect to each other, the structure exhibits the highest reduced material property parameter (D*). Conversely, positioning the layers at 90-degree angles [90°/90°/90°/90°] results in the lowest reduced material property parameters, elucidating the profound influence of the arrangement patterns of the CNTs on the structural and material behaviour of the composite. Given the nanostructure nature of the composite, this study leverages the nonlocal theory to delve into the electromagnetic wave propagation frequencies (ω) and meticulously scrutinise the behaviour of transmitted and reflected electromagnetic waves within the intricate layered structure. This nanocomposite structure has been engineered as a multi-layered system, with its design grounded in the principles of nonlocal theory. Within this framework, it is revealed that, as the nonlocal parameter (η) increases, there is a discernible reduction in the frequencies (ω) of EM wave propagation through the material. This in-depth analysis aims to contribute to a fundamental understanding of electromagnetic wave propagation behaviour in complex nanocomposite structures, with potentially far-reaching implications in various technological applications.
Journal Article