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This paper presents a mantle cloak structure to provide a wideband capability to hide a metallic cylinder over a broad span of angles of obliquely impinging plane waves. A bi-layered dielectric structure and a sheet of metasurface are used to enclose the object to be hidden. At first, the scattered field, including co- and cross-polarized components, is analytically formulated using circumferential waves for a multilayer wrap around the cylinder. A tensor description is also applied to model the impedance of the metasurface for TE and TM waves. Then, a metasurface made of rectangular patches is considered, and its related parameters are optimized to hide a perfect electric conductor (PEC) cylinder. Moreover, a double-layered mantle cloak is presented and numerically investigated using a software package to enhance its cloaking bandwidth. The numerical results show that the clocking bandwidth is enhanced by up to 33% compared to that of a single-layered structure. [ABSTRACT FROM AUTHOR]

Vibration in thin plates is a common issue in structural engineering that can significantly impact the performance of structures. One crucial objective is to control vibration intensity. Metamaterials offer a promising solution to this challenge. Herein, a multiband elastic waveguide cloak that uses metamaterials and does not require active components or complex designs is introduced. By converting flexural waves to waveguide-trapped waves, a cloaking region with negligible vibration can be created. Herein, independent mode conversion channels for elastic waves, which could lead to new approaches to modulating elastic waves, are discovered. The experiment results are in excellent agreement with the numerical simulation results and demonstrate a waveguide cloaking effect. This design has a compact structure and exhibits multiband performance, making it highly suitable for vibration control in various scenarios, including the aerospace industry, bridge engineering, and shock-absorbing platforms. [ABSTRACT FROM AUTHOR]

We present new exact results for the design of spherical thermal cloaks with the effect of imperfect interfaces. Thermal metamaterials are of great importance in advanced energy control and management. However, nearly all relevant studies considered that interfaces are ideally perfect. In principle, bonding imperfectness always exists at interfaces, and this effect is particularly important in small-length scales. Here, we will examine in detail the effect of bonding imperfectness on the performance of thermal functionality. The thermal metamaterial is made of a homogeneous spherically anisotropic material with a constant conductivity tensor. Low conductivity- and high conductivity-type interfaces are considered. We show how the anisotropic layer, together with the effect of imperfect bonding interfaces, can be made thermally invisible. An exact condition for thermal invisibility is derived in a simple algebraic form. Conditions for thermal shielding or enhancement are theoretically analyzed and numerically exemplified, in which relevant material and geometric parameters can be tuned to achieve the functionality. In addition, numerical simulations based on finite element calculations are carried out to validate our analytic solutions. The present findings offer a general guideline in the design of spherical thermal metamaterials with imperfect interfaces. [ABSTRACT FROM AUTHOR]

Manipulating transient mass transfer plays a crucial role in physics, chemistry, biology, and other fields. One typical example is chemical waves, whose concentration profiles have spatiotemporal variations. Based on a general model associated with the advection‐diffusion equation, an optimized transformation‐mass‐transfer theory is proposed to flexibly control transient mass transfer. As an example application, a class of separators is theoretically designed to achieve the separation of chemical waves. Meanwhile, three typical types of devices for cloaking, concentrating, and rotating chemical waves are proposed successfully, thus offering more versatile control methods. Such theoretical analysis is well confirmed by the computer simulations. These results provide insights into novel manipulation of chemical waves associated with biochemical reactions and promote potential applications for transient mass diffusion. [ABSTRACT FROM AUTHOR]

We introduce electrically thin cloaking devices that deflect a plane wave based on the principles of phase compensation and wave interference. An electrically large perfectly conducting object is cloaked by materials that control the phase velocity of the refracted wave. The design is based on gradient index materials to reflect incident waves in different directions resulting in a significant reduction in monostatic radar cross section. Unlike earlier cloaking devices that were constrained by specific geometry and involved complex media, the devices introduced here are electrically thin and can be made conformable to the surface of the structure to be cloaked. Numerical simulations are presented to validate the design concept presented here. [ABSTRACT FROM AUTHOR]

A three-dimensional acoustic device, which supports Fano resonance and induced transparency in its response to an incident sound wave, is designed and fabricated. These effects are generated from the destructive interference of closely coupled one broad- and one narrow-band acoustic modes. The proposed design ensures excitation and interference of two spectrally close modes by locating a small pipe inside a wider and longer one. Indeed, numerical simulations and experiments demonstrate that this simple-to-fabricate structure can be used to generate Fano resonance as well as acoustically induced transparency with promising applications in sensing, cloaking, and imaging. [ABSTRACT FROM AUTHOR]

Hitherto acoustic cloaking devices, which conceal objects externally, depend on objects' characteristics. Despite previous works, we design cloaking devices placed adjacent to an arbitrary object and make it invisible without the need to make it enclosed. Applying sequential linear coordinate transformations leads to a non-closed acoustic cloak with homogeneous materials, creating an open invisible region. Firstly, we propose to design a non-closed carpet cloak to conceal objects on a reflecting plane. Numerical simulations verify the cloaking effect, which is completely independent of the geometry and material properties of the hidden object. Moreover, we extend this idea to achieve a directional acoustic cloak with homogeneous materials that can render arbitrary objects in free space invisible to incident radiation. To demonstrate the feasibility of the realization, a non-resonant meta-atom is utilized which dramatically facilitated the physical realization of our design. Due to the simple acoustic constitutive parameters of the presented structures, this work paves the way toward realization of non-closed acoustic devices, which could find applications in airborne sound manipulation and underwater demands. [ABSTRACT FROM AUTHOR]

We present the theoretical design, numerical simulation, and experimental demonstration of a single-parameter-based underwater ultrasound cloaking of arbitrary objects based on metagrating. The carpet metagrating is implemented with periodic grooves, which circumvents the tedious calculations and extreme material responses of the conventional cloaking based on acoustic transformation theory, providing a simple design methodology and enabling easy fabrication in real-life scenarios. Particularly, we expand the working frequency range of this ultrasound cloaking to 100–900 kHz, which is commonly used in biomedical ultrasound and industrial testing. Our design with the advantages of extreme simplicity, robust concealment of sizeable objects, and potential broadband functionality will improve the applicability of ultrasound carpet cloaking for more realistic situations where the camouflage of the arbitrary target is needed. [ABSTRACT FROM AUTHOR]

Purpose: In this paper, we present strategies for active vibration suppression and defect detection in a one-dimensional network of an arbitrary number of coupled spring–mass units connected in series. The choice of a spring–mass system is not arbitrary, as the latter is found in many applications throughout a wide range of fields, for instance in defense detection/shielding studies, biomedical engineering, structures engineering, computer graphics and acoustics among others. Methods: The system of differential equations that model the spring–mass systems was analyzed and solved using the Laplace transform and other analytic tools. The data used in the numerical simulations were obtained by solving the associated forward problems analytically or numerically. Some of the simulations required numerical integration and minimization routines. Results: A scheme for active vibration suppression is given via explicit formulas for the required control forces. The detect defection strategy is given in terms of an explicit formula whenever only the location or mass of a lone defect is unknown and in terms of a minimization procedure whenever more than one information about the defect(s) are unknown. Several numerical simulations were done to validate these results. Conclusion: As we show in the paper, the success of the vibration suppression scheme we developed depends on the speed and accuracy of the intervening active controls. Meanwhile, the defect detection algorithm only requires measurements in a sufficiently large time interval of the longitudinal vibrations in the first mass. [ABSTRACT FROM AUTHOR]

In this paper, a new wearable (flexible) textile fabric-based 3D metamaterials absorber (MMA) structure is proposed. The proposed MMA was created from three layers; weft-knitted fabric, silicone, and plain weave fabric and then, it was simulated in Computer Simulation Technology (CST). It was obtained maximum absorption power (99.66%) at 9.38 GHz, and the average absorption power of 81-95% was obtained in the frequency range of 8 to 12 GHz depending on the incident angle in the simulation. The effect of the wearable textile structure on absorption was investigated. When compared with other materials, it can be said that the proposed MMA is broadband, incident angle independent, TE and TM polarization-independent, flexible, breathable, wearable, ease of fabrication, practical, low weight, and cost advantage. With this designed the textile fabric-based MMA, it can be obtained both low reflection coefficients and low transmission coefficients at broadband X-band frequencies. This provides a good solution for the cloaking of radar systems. [ABSTRACT FROM AUTHOR]

We consider the problem of hiding non-stationary objects from acoustic detection in a two-dimensional environment, where both the object's impedance and the properties of the detection signal may vary during operation. The detection signal is assumed to be an acoustic beam created by an array of emitters, which scans the area at different angles and different frequencies. We propose an active control-based solution that creates an effective moving dead zone around the object, and results in an artificial quiet channel for the object to pass through undetected. The control principle is based on mid-domain generation of near uni-directional beams using only monopole actuators. Based on real-time response prediction, these beams open and close the dead zone with a minimal perturbation backwards, which is crucial due to detector observers being located on both sides of the object's route. The back action wave determines the cloak efficiency, and is traded-off with the control effort; the higher is the effort the quieter is the cloaking channel. We validate our control algorithm via numerical simulations in a two-dimensional acoustic waveguide, testing variation in frequency and incidence angle of the detection source. Our cloak successfully intercepts the source by steering the control beams and adjusting their wavelength accordingly. [ABSTRACT FROM AUTHOR]

In this paper we establish the explicit expression for two-dimensional (2D) electro-magnetic cloaks of arbitrary star shapes without explicit contour expressions of the objects. Furthermore, 2D arbitrary star-shaped time domain cloak models are developed. A new finite element time domain (FETD) scheme is developed to solve the governing equations, and its stability is also proved. Numerical results are presented to confirm our theoretical analysis of the cloak models and the effectiveness of our FETD method. To our best knowledge, this is the first time domain finite element simulation of arbitrary star-shaped cloaks. [ABSTRACT FROM AUTHOR]

With the development of sensor technology and the popularization of the data-driven service paradigm, spatial crowdsourcing systems have become an important way of collecting map-based location data. However, large-scale task management and location privacy are important factors for participants in spatial crowdsourcing. In this paper, we propose the use of an R-tree spatial cloaking-based task-assignment method for large-scale spatial crowdsourcing. We use an estimated R-tree based on the requested crowdsourcing tasks to reduce the crowdsourcing server-side inserting cost and enable the scalability. By using Minimum Bounding Rectangle (MBR)-based spatial anonymous data without exact position data, this method preserves the location privacy of participants in a simple way. In our experiment, we showed that our proposed method is faster than the current method, and is very efficient when the scale is increased. [ABSTRACT FROM AUTHOR]

This paper presents the design and analysis of a novel biaxial double-negative (DNG) metamaterial for electromagnetic cloaking operation in the microwave range. The proposed metamaterial exhibits DNG characteristics for the three axes (x, y, and z axes) wave propagation through the material. For the z-axis wave propagation, it shows resonance in the X-band and shows DNG characteristics there. Similarly, for the x-axis wave propagation, the material displays resonances in the multi-band (S-, C-, and X-bands) microwave frequency ranges with DNG characteristics at the S-, C-, and X-bands. The material exhibits DNG properties at the S- and C-bands for y-axis wave propagation as well. In the basic design, a new metamaterial structure was developed that was split into two arms. The commercially available finite-difference time-domain (FDTD)-based computer simulation technology (CST) Microwave Studio software was adopted to obtain the reflection and transmission parameters of the unit cell. The metamaterial was then used in designing a rectangular electromagnetic cloaking device where a metal cylinder was perfectly cloaked in the C-band region of the microwave spectra. The metamaterial shows nearzero refractive-index property as well in the cloaked zone. This is a novel and promising design in the electromagnetic paradigm for its biaxial DNG characteristics and rectangular cloaking operation. [ABSTRACT FROM AUTHOR]

Perspective-correct occlusion-capable augmented reality displays are generalized using an optical cloak constraint for ray transfer analysis or simulations; any ray entering the optical system exits at the height and angle as if it passed through empty space. We analyze several systems with two-lens, three-lens, and four-lens looped groups in inline, folded, and looped configurations. We design and demonstrate a four-lens folded optical cloak and a three-lens inverted cloak with an erecting prism. [ABSTRACT FROM AUTHOR]

Thermal cloak has potential applications in thermal protection and sensing. Based on the theories of spatial transformation and effective medium, layered structure of elliptic cylindrical thermal cloak was designed. According to theoretical analysis and numerical simulation, the layered structure has typical characteristics of perfect thermal cloak. The external temperature field remains unchanged, while the internal temperature gradient decreases obviously. Meanwhile, the cloaking effect is stable in any direction. The cloaking effect can be improved by increasing the number of discretization layers or reducing the cloak thickness. The elliptic cylindrical cloak can be considered as cylindrical cloak when the focal distance is close to zero. This study has provided an effective way for realizing thermal cloak with more complex shapes. [ABSTRACT FROM AUTHOR]

‘Nonlinear invisibility cloak’ using metamaterial is presented in this paper. To comprehend the said, the notion of point source, cylindrical source, perfect metamaterials and reduced metamaterials are taken for cloaking application. Transformation optics to the metamaterial envisages an interesting variation of both clocking shape and cloaking area with respect to aspect ratio. Simulation results revealed that both cloaking area and cloaking configuration are changed nonlinearly in case of (point source, exact metamaterial), (point source, reduced metamaterial), (cylindrical source, exact metamaterial) and (cylindrical source, reduced metamaterial). [ABSTRACT FROM AUTHOR]

Thermal cloaks have potential applications in thermal protection and sensing, and those cloaks with complex shapes are much more efficient in application. Layered discretization is a valid way to realize thermal cloaks designed through spatial transformation which are usually nonhomogeneous and anisotropic. However, previous studies are limited to two-dimensional cylindrical ones. Based on the theories of spatial transformation and effective medium, a four-step design method for layered structure of thermal cloak with complex shape is proposed. It is expected to realize the designed layered structure by utilizing the existing regular materials. According to the numerical simulations, the thermal cloaking performances of layered structures are good and close to that of the perfect thermal cloaks. This study has provided an effective way for realizing thermal cloak with complex shape. [ABSTRACT FROM AUTHOR]

In this paper, an efficient integral equation method is developed for the response and scattering characteristics of cloaked 2-D planar microstrip receiving antennas. The featured technique combines Green’s function for the strip-free structure with the decomposition of the strip into cylindrical thin wires and a radiation integral evaluation for the scattered field. In essence, the desired low-profile operation of the antenna is achieved by overlaying a superstrate slab atop the antenna. Moreover, an optimization process determines the constitutive parameters and thickness of the slab, so that a significantly reduced scattering behavior is obtained. Finally, the performance of the receiving antenna is investigated for a specific range of frequencies around the operating one, while the accuracy of the proposed algorithm is successfully verified through several numerical simulations. [ABSTRACT FROM AUTHOR]

Based on classical EM field theory, the distributions of energy density and energy flow velocity in the 2-D cylinder cloak have been calculated. Due to the variable and special electromagnetic (EM) parameters, theoretical results indicate that the EM fields, EM energy density and EM energy flow are non-uniform in the cloak shell. The numerical simulations show that there is superluminal phenomena of the velocity of energy flow in the cloak shell, whether the EM field transmit along x -direction or along y -direction. [ABSTRACT FROM AUTHOR]

In this review, a brief introduction is given to the development of acoustic superlens cloaks that allow the cloaked object to receive signals while its presence is not sensed by the surrounding, which can be regarded as “cloaking an acoustic sensor”. Remarkably, the designed cloak consists of single-negative materials with parameters independent of the background medium or the sensor system, which is proven to be a magnifying superlens. This has facilitated significantly the design and fabrication of acoustic cloaks that generally require double-negative materials with customized parameters. Such innovative design has then been simplified further as a multi-layered structure comprising of two alternately arranged complementary media with homogeneous isotropic single-negative materials. Based on this, a scattering analyses method is developed for the numerical simulation of such multi-layered cloak structures, which may serve as an efficient approach for the investigation on such devices. [ABSTRACT FROM AUTHOR]

This paper deals with the numerical design of a directional invisibility cloak for backward scattered elastic waves propagating in a thin plate (A0 Lamb waves). The directional cloak is based on a set of resonating beams that are attached perpendicular to the plate and are arranged at a sub-wavelength scale in ten concentric rings. The exotic effective properties of this locally resonant metamaterial ensure coexistence of bandgaps and directional cloaking for certain beam configurations over a large frequency band. The best directional cloaking was obtained when the resonators' length decreases from the central to the outermost ring. In this case, flexural waves experience a vanishing index of refraction when they cross the outer layers, leading to a frequency bandgap that protects the central part of the cloak. Numerical simulation shows that there is no back-scattering in these configurations. These results might have applications in the design of seismic-wave protection devices. [ABSTRACT FROM AUTHOR]

The goal of this paper is to prove the well-posedness for the governing equations which are used for cylindrical cloaking simulation. A new time-domain finite element scheme is developed to solve the governing equations. Numerical results demonstrating the cloaking phenomenon with the cylindrical cloak are presented. We finally extend the analysis and simulation to an elliptical cloak model. [ABSTRACT FROM AUTHOR]

For ideal invisibility cloaks, electromagnetic radiations cannot penetrate through the cloaking shell. However, researchers have suggested that the originally hidden object with a cloaking shell is visible to the outside world when it is covered by an "anticloak." In this paper, we give the first experimental verification of the "anticloak" for the Laplace equation, which requires negative conductivity profiles. The proposed device consists of two layers-the cloak and anticloak, which can work individually or collectively and give rise to different functions. Functionality switching among the invisibility cloak, anticloak, transparent eloak, superscatterer, and illusion is suggested and demonstrated. Based on the circuit theory, we fabricate a switching resistor network with both positive and negative resistors to emulate the cloaking and anticloaking interactions. The switchable cloaking, anticloaking, transparent, superscatterer, and illusion performances are confirmed by the experiments and/or numerical simulations. [ABSTRACT FROM AUTHOR]

In recent years, invisibility cloaks have received a lot of attention and interest. These devices are generally classified into two types: passive and active. The design and realization of passive cloaks have been intensively studied using transformation optics and plasmonic approaches. However, active cloaks are still limited to theory and numerical simulations. Here, we present the first experiment on active cloaking and propose an active illusion for the Laplace equation. We make use of a resistor network to simulate a conducting medium. Then, we surround the central region with controlled sources to protect it from outside detection. We show that by dynamically changing the controlled sources, the protected region can be cloaked or disguised as different objects (illusion). Our measurement results agree very well with numerical simulations. Compared with the passive counterparts, the active cloaking and illusion devices do not need complicated metamaterials. They are flexible, in-line controllable, and adaptable to the environment. In addition to dc electricity, the proposed method can also be used for thermodynamics and other problems governed by the Laplace equation. [ABSTRACT FROM AUTHOR]

Abstract: We theoretically examine the cloaking condition for two-dimensional particles with varying geometry embedded inside a surface medium. General solutions are obtained for multi-layer particle configurations with either all positive or partially negative constitutive parameters respectively. Cloaking of particle geometries that are large relative to the incident wavelength is demonstrated. Theoretical predictions are compared to full-wave numerical simulations for arrays of particles consisting of different geometries. [Copyright &y& Elsevier]

A novel cloaking scheme to hide an object in a half space from electromagnetic (EM) detection without reflection is firstly presented. The proposed cloaking scheme contains a couple of matching strips, which consist of an isotropic material layer and an anisotropic UPML layer, located right under the bottom surface of a semi-cylindrical cloaking shell. Simple expressions for the material parameters of the cloaking scheme are derived. Numerical simulations are also performed, and a good cloaking effect is achieved. The cloaking scheme is effective to hide the local object with strong scattering characters placed on mobile carriers, such as the radar antenna system on an aircraft. [ABSTRACT FROM AUTHOR]

show that conformal cloak can not only work in geometrical optics limit but also in wave optics, if the working frequency is at the eigenfrequencies of the refractive index profile applied in the lower Riemann sheet (the profile is a special one that pushes light rays to propagate in close orbits). In this paper, we propose a more general concept of conformal cloaks for waves. We find that simply with a cavity set in the lower sheet, can the devices perform as good cloaking effect if the cavity mode can be excited out. The effect is not valid in geometrical optics limit but only for waves. Numerical simulations are performed to verify our findings. [ABSTRACT FROM AUTHOR]

In this article, we review definition, origin, terminology, fundamental properties, design concepts and procedures, basic applications, modeling, and numerical simulation of metamaterials. It is shown that metamaterial origin can be easily understood by placing metamaterials in the more general context of artificial electromagnetic materials and of the efforts performed by the scientific community working in complex materials to mimic and overcome the properties of natural materials. The basic properties of some classes of metamaterials as well as the related limitations are reviewed and discussed. A new application-oriented definition of metamaterials is given in terms of a functionalizing layer placed in between the traditional concepts of materials and devices. Metamaterial applications and the design steps of metamaterial-based and metamaterial-inspired components are also discussed, with particular emphasis on the numerical simulation of ideal metamaterials through available solvers. In this frame, finite-difference time-domain (FDTD) modeling and simulation of the electromagnetic properties of metamaterials are deeply discussed. The recently introduced virtual MTM-FDTD tool is used to simulate the interaction between the electromagnetic field and metamaterials and show some metamaterial effects, such as beam focusing, existence of negative refractive angle, and so forth, through various examples in different scenarios. © 2012 Wiley Periodicals, Inc. Int J RF and Microwave CAE 22:422-438, 2012. [ABSTRACT FROM AUTHOR]

We demonstrate a finite-difference time-domain (FDTD) modeling of a cloak with a nondiagonal permittivity tensor. Numerical instability due to material anisotropies is avoided by mapping the eigenvalues of the material parameters to a dispersion model. Our approach is implemented for an elliptic-cylindrical cloak in two dimensions. Numerical simulations demonstrated the stable calculation and cloaking performance of the elliptic-cylindrical cloak. [ABSTRACT FROM AUTHOR]

Periodically engineered structures, having the capability to manipulate mechanical wave propagation and exhibiting omnidirectional phononic band gaps, are important for various potential applications such as wave filtering, waveguiding, acoustic cloaking, thermal management, and energy harvesting. In natural materials, vibration mitigation capability depending on inherent damping feature usually cannot be adjusted easily and broad attenuation frequency ranges are still uncommon in these materials. Here, inspired by the Hoberman sphere architecture, we propose a novel lattice system with broad and multiple omnidirectional phononic band gaps, which are attributed to the local resonances mechanism. Guided by numerical simulations, analytical formulations, and low amplitude transmission testing, we show that the proposed lattice metamaterials can exhibit broad and multiple omnidirectional band gaps over a wide range of node connectivity and constituents. The finding reported here provides a new routine to design phononic metamaterial systems with tunable band gaps, offering a wide range of potential applications in harsh environmental conditions. Unlabelled Image • A class of metamaterials with multiple and wide band gaps is proposed. • The analytical formulations are conducted by combining triangular element, consistent mass method, dynamic equilibrium equation, Floquet periodical boundary and Bloch theorem. • Finite element simulations are performed to study the role of middle rods from hard to soft and the mechanism of band gaps. • The low amplitude transmission testing is implemented to verify the numerical simulations. [ABSTRACT FROM AUTHOR]

Inspired by electromagnetic waveguide cloaks with gradient index metamaterials, we fabricated a broadband cloak with simply a gradient depth profile on the bottom and without any other structures on the top to confine water waves in a certain area for cloaking regions. The new physics of mode conversion for water waves is first found. The experimental and numerical simulation results are in good agreement and show that the presented device has a nice performance for various situations and is feasible over a broadband of working frequencies. Being easy to construct, this design is potentially of significance for port applications. [ABSTRACT FROM AUTHOR]

Conventional carpet cloak structures have been utilized to conceal the objects located on a planar perfect electric conductor surface. We systematically investigate hiding arbitrarily shaped objects on a rough surface, as a more general and practical scenario. In addition, the required cloak is designed considering different boundary conditions for the surface beneath the object, despite the previous studies. To achieve an invisibility cloak, taking advantage of linear coordinate transformation, a simple homogeneous material is obtained to realize the cloak structure, facilitating the fabrication processes. Numerical simulations validate the performance of the proposed cloaking method. Therefore, the proposed structure is capable of cloaking in more general and complicated scenarios. [ABSTRACT FROM AUTHOR]

We propose open active cloaking and illusion devices for the Laplace equation. Compared with the closed configurations of active cloaking and illusion devices, we focus on improving the distribution schemes for the controlled sources, which do not have to surround the protected object strictly. Instead, the controlled sources can be placed in several small discrete clusters, and produce the desired voltages along the controlled boundary, to actively hide or disguise the protected object. Numerical simulations are performed with satisfactory results, which are further validated by experimental measurements. The open cloaking and illusion devices have many advantages over the closed configurations in various potential applications. [ABSTRACT FROM AUTHOR]

Electromagnetic invisible devices usually designed by transformation optics are rather complicated in material parameters and not suitable for general applications. Recently, a topology optimized cloak based on level-set method was proposed to realize nearly perfect cloaking [Fujii et al., Appl. Phys. Lett. 102, 251106 (2013)]. In this work, we experimentally implemented this idea and fabricated a unidirectional cloak with a relative large invisible region made of single dielectric material. Good cloaking performance was verified through measurement which consists very well with numerical simulation. The advantages and disadvantages of this optimization method are also discussed. [ABSTRACT FROM AUTHOR]