There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

Thank you for reading principles of optics electromagnetic theory of propagation interference and diffraction of light. As you may know, people have search hundreds times for their favorite novels like this principles of optics electromagnetic theory of propagation interference and diffraction of light, but end up in harmful downloads. Rather than enjoying a good book with a cup of coffee in the afternoon, instead they are facing with some infectious bugs inside their computer.

Principles Of Optics Electromagnetic Theory Of Propagation Interference And Diffraction Of Light

This work was supported by National Basic Research Program of China
(Project No. 2013CB933301) and National Natural Science Foundation of
China (Project No. 51272038). L.V.B. was supported by China Postdoctoral
Science Foundation. A.O.G. was supported by the Volkswagen
Foundation (Germany) and via the Chang Jiang (Yangtze River)
Chair Professorship (China). G.P.W. acknowledges support from the
Center for Nanoscale Materials, a U.S. Department of Energy Office of
Science User Facility, and support by the U.S. Department of Energy,
Office of Science, under Contract No. DE-AC02-06CH11357. In addition,
the authors acknowledge financial support obtained from the Virtual
Institute for Theoretical Photonics and Energy. This review is part of the
Advanced Optical Materials Hall of Fame article series, which recognizes
the excellent contributions of leading researchers to the field of optical
materials science.

/pdf/broadband-metamaterial-absorbers-1ivwczjh1w.pdf

Broadband Metamaterial Absorbers

A simple, fast and efficient method for designing wideband radar absorbers is proposed. The idea is to modify the circuit analog absorber method without perturbing the bandwidth. This is done by utilizing the asymptotic behavior of such an absorber at low frequency and replacing the band-stop resonating frequency selective surfaces with low-pass capacitive ones, which can be synthesized by square patches. It is shown that higher frequencies are not influenced by these modifications. A thin wideband capacitive circuit absorber (CCA) is presented with 28% reduction of thickness and 57% increase of bandwidth in comparison to the Salisbury screen. It is also explained why some optimized metamaterial designs fail to compete with the CCA method. For high permittivity layers, it is shown that the CCA is a better solution than the Jaumann absorber and improvements both in thickness and bandwidth are possible. A three layered ultra wideband (4-24 GHz) CCA is presented with total thickness of 15.1 mm. Finally, a design capable of handling oblique angles of incidence for both polarizations and fulfilling different mechanical, thermal and fabrication constraints is given. The absorption band covers the entire C, X and Ku radar bands (4-18 GHz), showing significant improvement compared to the published circuit analog absorbers. (Less)

/pdf/capacitive-circuit-method-for-fast-and-efficient-design-of-2slqpdlohd.pdf

Capacitive Circuit Method for Fast and Efficient Design of Wideband Radar Absorbers

Although various photonic devices inspired by natural materials have been developed, there is no research focusing on multibands adaptability, which is not conducive to the advancement of materials science. Herein, inspired by the moth eye surface model, state-of-the-art hierarchical metamaterials (MMs) used as tunable devices in multispectral electromagnetic-waves (EMWs) frequency range, from microwave to ultraviolet (UV), are designed and prepared. Experimentally, the robust broad bandwidth of microwave absorption greater than 90% (reflection loss (RL) < -10 dB) covering almost entire X and Ku bands (8.04-17.88 GHz) under a deep sub-wavelength thickness (1 mm) is demonstrated. The infrared emissivity is reduced and does not affect the microwave absorption simultaneously, further realizing anti-reflection and camouflage via the strong visible light scattering by the microstructure, and can prevent degradation by reducing the transmittance to less than 10% over the whole near UV band, as well as having hydrophobic abilities. The mechanism explored via simulation model is that topological effects are found in the bio-structure. This discovery points to a pathway for using natural models to overcome physical limits of MMs and has promising prospect in novel photonic materials.

Bioinspired Metamaterials: Multibands Electromagnetic Wave Adaptability and Hydrophobic Characteristics.

Optically Transparent Microwave Metamaterial Absorber (OTMMA) is of significant use in both civil and military field. In this paper, equivalent circuit model is adopted as springboard to navigate the design of OTMMA. The physical model and absorption mechanisms of ideal lightweight ultrathin OTMMA are comprehensively researched. Both the theoretical value of equivalent resistance and the quantitative relation between the equivalent inductance and equivalent capacitance are derived for design. Frequency-dependent characteristics of theoretical equivalent resistance are also investigated. Based on these theoretical works, an effective and controllable design approach is proposed. To validate the approach, a wideband OTMMA is designed, fabricated, analyzed and tested. The results reveal that high absorption more than 90% can be achieved in the whole 6~18 GHz band. The fabricated OTMMA also has an optical transparency up to 78% at 600 nm and is much thinner and lighter than its counterparts.

/pdf/theoretical-analysis-and-design-of-ultrathin-broadband-1hq915iu8l.pdf

Theoretical Analysis and Design of Ultrathin Broadband Optically Transparent Microwave Metamaterial Absorbers.

This paper presents an ultracompact design of biomedical implantable devices with integrated wireless power transfer (WPT) and RF transmission capabilities for implantable medical applications. By reusing the spiral coil in an implantable device, both RF transmission and WPT are realized without the performance degradation of both functions in ultracompact size. The complete theory of WPT based on magnetic resonant coupling is discussed and the design methodology of an integrated structure is presented in detail, which can guide the design effectively. A system with an external power transmitter and implantable structure is fabricated to validate the proposed approach. The experimental results show that the implantable structure can receive power wirelessly at 39.86 MHz with power transfer efficiency of 47.2% and can also simultaneously radiate at 2.45 GHz with an impedance bandwidth of 10.8% and a gain of −15.71 dBi in the desired direction. Furthermore, sensitivity analyses are carried out with the help of experiment and simulation. The results reveal that the system has strong tolerance to the nonideal conditions. Additionally, the specific absorption rate distribution is evaluated in the light of strict IEEE standards. The results reveal that the implantable structure can receive up to 115 mW power from an external transmitter and radiate 6.4 dB·m of power safely.

Ultracompact Implantable Design With Integrated Wireless Power Transfer and RF Transmission Capabilities

Luneburg lens with flat focal surface has been developed to work together with planar antenna feeds for beam steering applications. According to our analysis of the conventional flattened Luneburg lens, it cannot accommodate enough feeding elements which can cover its whole scan range with half power beamwidths (HPBWs). In this paper, a novel Luneburg lens with extended flat focal surface is proposed based on the theory of Quasi-Conformal Transformation Optics (QCTO), with its beam steering features reserved. To demonstrate this design, a three-dimensional (3D) prototype of this novel extend-flattened Luneburg lens working at Ku band is fabricated based on 3D printing techniques, whose flat focal surface is attached to a 9-element microstrip antenna array to achieve different scan angles. Our measured results show that, with different antenna elements being fed, the HPBWs can cover the whole scan range.

Luneburg lens with extended flat focal surface for electronic scan applications

In this paper, a full solid angle scanning cylindrical-and-conical (CYLCON) conformal phased array antenna (PAA) is designed. First, a microstrip Yagi antenna with low profile and small size is proposed and discussed. Second, a cylindrical conformal Yagi antenna array consisting of 24 aforementioned 8-element Yagi antennas is designed and optimized. Simulation results show that the Yagi antenna array can realize low-elevation beam scanning in the region of $ 0 {^{\circ }} \le \theta \le 30 {^{\circ }}$ , $30 {^{\circ }} \le \varphi \le 150 {^{\circ }}$ with low sidelobe levels and sharp beams. Third, CYLCON conformal microstrip antenna arrays are developed to realize the broadside beam scanning. Afterwards, an integrated PAA by combining the aforementioned conformal arrays along with feeding networks is constructed to achieve full solid angle scanning. Finally, a prototype is fabricated, the measured results show that it can realize beam scanning in the regions of $ 0 {^{\circ }} \le \theta \le 30 {^{\circ }}$ , $30 {^{\circ }} \le \varphi \le 150 {^{\circ }}$ , and $30 {^{\circ }} \le \theta \le 180 {^{\circ }}$ , $60 {^{\circ }} \le \varphi \le 120 {^{\circ }}$ , which meet well with those of the simulated. By arranging proper number of arrays along the perimeter accompanied with the switchable feeding configurations, a full solid angle scanning can be achieved.

Qi Zhu

Papers

Theoretical Analysis and Design of Ultrathin Broadband Optically Transparent Microwave Metamaterial Absorbers.

Ultracompact Implantable Design With Integrated Wireless Power Transfer and RF Transmission Capabilities

Luneburg lens with extended flat focal surface for electronic scan applications

Design of a Full Solid Angle Scanning Cylindrical-and-Conical Phased Array Antennas

A Broadband Compatible Multispectral Metamaterial Absorber for Visible, Near‐Infrared, and Microwave Bands