Chessboard Configuration Research Articles

Ultra-wide band and high efficient Polarization converting metasurface employing Bell-shaped unit cell for RCS reduction

Polarization is a dominant parameter regarding communication systems in recent times. The standard polarization techniques can be used only to a certain extent because of their huge size and limited bandwidth constraints. A design of bell-shaped polarization converting metasurface (PCMS) is presented in this paper which is highly efficient for Radar cross section (RCS reduction) and also operates in ultra-wideband. The designed PCMS attains a polarization conversion ratio of more than 90% by demonstrating the transformation of the linear polarization wave to its orthogonal counterpart. The PCMS is arranged in a triangular chessboard configuration to reduce the RCS. RCS reduction is obtained by achieving destructive interference, accomplished by two unit cells. The two unit cells, PCMS and its mirror will have a phase difference of 180 ± 37°. The phase cancellation is obtained by rotating and arranging the proposed PCMS at 90°, 180° and 270°. RCS reduction is obtained in a frequency range from 4 GHz to 24.8 GHz with 144% FBW. This PCMS is verified experimentally. A good agreement is found between the simulation and the experimental results.

A Wideband Polarization-Insensitive Bistatic Radar Cross-Section Reduction Design Based on Hybrid Spherical Phase-Chessboard Metasurfaces

A wideband polarization-insensitive bistatic radar cross-section (RCS) reduction design under linear and circular polarization incidence is proposed based on spherical-chessboard metasurfaces. A new metasurface element with wideband characteristics was designed, including a double split-ring structure, single-layer media, and metal board. In the proposed RCS-reduction design, the Pancharatnam–Berry (P-B) phase theory is applied with the designed metasurface element to realize phase distribution mimicking the low-scattering sphere, and thus realizing RCS reduction. In addition, the chessboard configuration is combined with spherical phase distribution to further improve the performance of monostatic and bistatic RCS reduction. Finally, the proposed RCS reduction design can not only realize wideband RCS reduction but also exhibit polarization-insensitive characteristics. It realized 10 dB monostatic and bistatic RCS reduction in a frequency band ranging from 8.5 to 21 GHz (84.8% relative bandwidth) under linear polarization (LP) and circular polarization (CP) incidence. The straightforward and efficient design method of the hybrid spherical chessboard can effectively avoid the complex and time-consuming optimization process in RCS-reduction design.

A switchable PCM-based integrated structure with alternative radiation and stealth functions

In this work, based on the switchable polarization conversion metasurface (SPCM), the dual functions of high gain right-handed circularly polarized (RHCP) radiation and wideband 10 dB radar cross section (RCS) reduction stealth are achieved in one structure. As the key component to achieve good radiation and low RCS, the proposed SPCM unit consists of the asymmetrical Jerusalem Cross top layer and switchable metal plate bottom layer separated by an air space. Then the SPCMs are arranged in a chessboard configuration and placed above a patch array antenna with the sequentially rotated feeding network. When p-i-n diodes are on, low RCS is implemented by 180° (±37°) reflection phase differences between two neighboring SPCM cells. When p-i-ns are off, the chessboard SPCM provides a transmission window for highly directional RHCP wave radiation.

Broadband RCS Reduction Using Circular Sector Structure

In this paper, a new metasurface structure is designed to reduce radar cross section (RCS). In order to reduce the radar cross section (RCS), a new metasurface structure is designed. The unit adopts the polarization conversion metasurface structure, which is composed of asymmetric double arrow-shaped metal structure and etched on the dielectric substrate on the back of the metal plate. This polarization conversion metasurface (PCM) unit consists of asymmetric double arrow-shaped metal structure, and it is etched on a dielectric substrate backed with metallic plate. It can realize converting linear polarized waves to orthogonal ones in a broadband from 18.1 GHz to 32.7 GHz efficiently. According to the further development of the triangle chessboard layout, we also designed several new circular fan-shaped configurations, which realize RCS reduction in a wider -10 dB bandwidth compared with the triangle chessboard configuration. Finally, an optimized 8-lobed circular sector configuration composed of the designed PCM unit is selected for processing and testing. It can realize the RCS reduction greater than 10 dB in a wide bandwidth ranging from 13.7 GHz to 27.5 GHz, compared with the equal-sized metallic-backed dielectric substrate plate. The experimental results basically agree with the simulation ones. The proposed broadband circular sector structure has broad application prospects such as phased array antenna technology, electromagnetic stealth technology, and electromagnetic absorption technology.

Reconfigurable chessboard coding plasma-based dielectric resonator structure for RCS reduction

In this paper, reconfigurable chessboard coding plasma-based dielectric resonator structure for radar cross section reduction is investigated. The radar cross section (RCS) reduction is essential in military applications. The metallic conductor surface is covered with plasma-based dielectric resonator (DRA) unit-cells arranged in chessboard configuration. The plasma DRA unit-cell consists of concentric cylindrical ring filled with ionized plasma placed over FR4 dielectric substrate. The plasma ionization voltage values are tuned to reflect the electromagnetic wave with phase shift of 180° and equal amplitudes. The phase 0° state represents the logic “0” while the phase 180° state represents the logic “1”. The chessboard arrangement consists of super-cells with 0/1 logic states. Different sizes of uniform super-cells 3 × 3, 4 × 4, 6 × 6, and 12 × 12 unit-cells are investigated for maximum RCS reduction. The scattered beams are directed to (± 30°, 180° ± 30°), (± 25°, 180° ± 25°), (± 20°, 180° ± 20°), (± 15°, 180° ± 15°) and (± 10°, 180° ± 10°) for 3 × 3, 4 × 4, 6 × 6, 8 × 8, and 12 × 12 uniform super-cells, respectively. The RCS is reduced over a wide angle range reduction with − 18 dBm2 at the broadside direction and below − 32 dBm2 over the angular range from − 90° to 90° according to the super-cell size. The non-uniform allocation of unit-cells in the super-cell chessboard arrangement is investigated. The RCS reduction bandwidth extended from 8.5 to 9.65 GHz. The scattered beam produces null in the broadside direction with wideband RCS reduction. The proposed structures are simulated using CST-MWS electromagnetic simulator.

An Optically Transparent Hybrid Mechanism Metasurface for Wideband, Wide-Angle and Omnidirectional Scattering Suppression

Metasurface provides an efficient method to regulate wave propagation in multiphysics fields ranging from light waves, electromagnetic (EM) waves, and acoustic waves. Considering the versatile demands in practical scenarios, the essential challenge is to design the metasurface with spectral compatibility to satisfy the various applications. Here, we proposed an optically transparent hybrid mechanism metasurface (HMM) incorporating absorption, polarization conversion, and phase cancellation mechanisms for wideband, wide-angle, and omnidirectional scattering suppression performance. The unit cell integrates absorption and polarization conversion capabilities by etching the indium tin oxide (ITO) film into the specific structure, exhibiting wideband ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$7.44-31.31$ </tex-math></inline-formula> GHz), wide-angle ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\!&lt; 45^{\circ }$ </tex-math></inline-formula> ), high-efficiency ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\!\ge 90$ </tex-math></inline-formula> %), and omnidirectional co-polarized scattering suppression performance. Moreover, the phase cancellation mechanism is implemented by distributing the unit cell and its mirror structure in the chessboard configuration, which provides cross-polarized reflection reduction capability for the HMM. Therefore, the HMM achieves a significant total radar cross section (RCS) reduction by integrating multiple scattering suppression mechanisms. Eventually, the simulated and measured results indicate that the proposed HMM can realize more than 10 dB total monostatic and bistatic RCS reduction within 7.49-32.23 and 7.46-30.55 GHz, respectively. In addition, good specular and omnidirectional RCS reduction capabilities are also obtained. Furthermore, the HMM also presents good optical transparency, which is attributed to the high transmittance of the polyethylene terephthalate (PET) substrates and the ITO films. The proposed strategy has potential application in the multifunctional stealth design of stealth platforms.

High efficient and ultra-wideband polarization converter based on I-shaped metasurface for RCS reduction

In modern communication systems, polarization has always been a major issue. Traditional polarization converters have limited uses because of their enormous size and narrow bandwidth. In this paper, an ultra-wideband and high efficient polarization converting metasurface (PCMS) is designed for radar cross section (RCS) reduction. The designed PCMS consists of I-shape unit cell manifesting linearly polarized (LP) incident wave to its orthogonal equivalent. In a frequency range of 10.5 GHz to 29.5 GHz, the design PCM achieves a polarization conversion ratio (PCR) more than 90% with 95% fractional bandwidth (FBW). The designed PCMS is used in a triangular chessboard configuration to reduce the RCS. To obtain destructive interference, the proposed array consists of two-unit cells, PCMS and its mirror, with a phase difference of 180 ± 37°. To reduce RCS, the proposed PCMS unit cell is rotated at 90°, 180°, and 270° for phase cancellation. The proposed array reduced RCS in the ultra-wide frequency range of 8.2 GHz to 29.4 GHz with 113% FBW. The proposed PCMS is validated experimentally. Simulation and experimental results are found in good agreement.

Diffusive Energy-Selective Surface With Low Backscattering

In this article, a diffusive energy-selective surface (ESS) is proposed for obtaining high-power electromagnetic (EM) protection and low backscattering at the same time. With properly designed unit cell structures, the ESS is almost transparent to an incident wave of low power, while it fully rejects the high-power incidence. Meanwhile, the ESS unit cells are endowed with different reflection phases. Therefore, when arranged in a chessboard configuration, the high-power waves rejected by the ESS are diffused into other directions resulting in a low backscattering. To demonstrate the design concept, a diffusive ESS with an operating frequency of 3 GHz is designed. A unit cell with an asymmetric structure is proposed, which provides identical transmission coefficients but opposite reflection phases on its two sides. By properly assembling the unit cell and its mirror, an ESS with low-power transmission and high-power diffusive backscattering is designed. Equivalent circuit models are constructed to analyze the unit cell and to formulate the design guidelines. Moreover, the diffusive ESS is fabricated and measured based on the free-space setup, where a good agreement is observed between the simulation and measurement. The transmission magnitude is larger than −0.5 dB and smaller than −25 dB under the low- and high-power normal incidences at the operating frequency. In addition, the backscattering of the ESS is reduced significantly in comparison with a metallic plate of the same size.

Wideband and wide-angle radar cross section reduction using a hybrid mechanism metasurface.

In this paper, a hybrid mechanism metasurface (HMM) that incorporates absorption, polarization conversion and phase cancellation mechanisms is proposed for wideband and wide-angle radar cross section (RCS) reduction. The polarization conversion absorber (PCA) is proposed by embedding the lumped resistors into the polarization conversion structure, which integrates the absorption and polarization conversion mechanisms. Then, the phase cancellation mechanism is employed to redirect the scattering energy to the non-incident directions through the chessboard configuration, which exploits the opposite phase between the PCA and its mirror structure. Unlike previous HMMs that depended on nested or cascaded structures, the proposed strategy integrates the absorption and polarization conversion mechanisms in the same structure, and the two mechanisms are complementary to each other. Through the integration of multiple mechanisms, the HMM can achieve more than a 10 dB monostatic and bistatic RCS reduction in 8.7-32.5 GHz and 8.6-31.2 GHz, respectively. Furthermore, the specular and bistatic RCS reduction performances under oblique incident waves are also studied, and the stable scattering suppression performances are determined. The proposed hybrid mechanism strategy exhibits significant scattering suppression capability through the incorporation of multiple mechanisms, which have potential applications in the multifunctional metasurface.

Trifunctional metasurface based on spoof surface plasmon polaritons.

In this paper, we propose the design of a metasurface that can achieve three functions in different frequency bands. The proposed metasurface is composed of two kinds of unit cells which are designed on the basis of the spatial k-dispersion engineering of spoof surface plasmon polaritons (SSPPs). By arranging these two kinds of unit cells in the chessboard configuration, the three functions of transmission, anomalous refraction and absorption can be integrated into one metasurface. High transmission and strong absorption can be achieved in 2.0-9.0 GHz and 12.6-20.0 GHz, respectively. Meanwhile, anomalous refraction can be achieved in 10-11.7 GHz due to forward scattering cancellation of two unit cells. To verify the design, a prototype was fabricated and measured. The measured results are consistent with the simulation ones. The metasurface can integrate multiple functions into one aperture and therefore has potential application values in multifunctional microwave devices such as shared-aperture antennas, etc.

Wavevector and Frequency Multiplexing Performed by a Spin‐Decoupled Multichannel Metasurface

AbstractAchieving kaleidoscopic wavefront controls with a thin flat plate is pivotal for increasing data capacity yet still challenging in integrated optics. An anisotropic metasurface provides an efficient recipe primarily for linear polarization, but is less efficient for multiple functionalities at arbitrary spin states. Here, a strategy of realizing a spin‐decoupled high‐capacity multifunctional metasurface by multiplexing the frequency and wavevector degree of freedom (DoF) is reported. By integrating both geometric and dynamic phases in split ring resonators and crossbars in a chessboard configuration, the inherent limitation of spin‐flipped Pancharatnam–Berry phases can be completely decoupled between two spin states. Such released extraordinary DoF unprecedentedly increases the capability to yield kaleidoscopic wavefront control. To verify the significance, two proof‐of‐concept metadevices that are nearly impossible in conventional metasurfaces are experimentally demonstrated with four‐port wavefront manipulations, exhibiting spin‐, frequency‐, and wavevector‐dependent anomalous reflections, lensing, orbital angular momentum generation, and wavevector‐multiplexed vortex scattering, along with two‐dimensional holograms. Both numerical and experimental results illustrate quad‐distinct functionalities with up to ten channel beams and ≈93% efficiency, because of the completely suppressed crosstalk among different operation modes, angular wavevectors, and spins. The finding in triple‐DoF multiplexing is expected to generate great interest in electromagnetic integration with emerging DoFs.

A Low-Profile Wideband Tightly Coupled Dipole Array With Reduced Scattering Using Polarization Conversion Metamaterial

A novel approach aimed at reducing the out-of-band scattering cross section (SCS) and preserving the radiation characteristics of a low-profile wideband tightly coupled dipole array (TCDA) operating in P-L band is presented. The array is designed without wide-angle impedance matching (WAIM) layers for low profile and simple topological structure. The SCS reduction of the proposed TCDA is achieved by loading the array with polarization conversion metamaterial (PCM). The PCM is arranged in a chessboard configuration and placed on the ground plane of the TCDA. The infinite array is able to achieve a 4:1 bandwidth from 0.5 to 2.0 GHz, with VSWR $8 \times 8$ TCDA prototype is fabricated and measured. The experimental results are in good agreement with simulated results. The simulated and experimental results demonstrate that by using the proposed approach with PCM, the monostatic SCS is significantly reduced within 6.0–18.0 GHz under normal incidence. Meanwhile, the radiation characteristics are well preserved in the operating band of the TCDA.

Design and development of low radar cross section antenna using hybrid metamaterial absorber

AbstractAn efficient approach is presented in this article, to reduce radar cross section (RCS) of a microstrip patch antenna, without affecting other radiation characteristics by the application of a novel hybrid metamaterial (MM) structure. The microstrip antenna is designed to operate at 4.2 GHz. Three different configurations of MM structures (ie, CB_1, CB_2, and hybrid) with splitted square and ring shaped two nonidentical MM cells are designed and critically analyzed in the range of 2‐18 GHz. A hybrid MM configuration is chosen for the design and implementation of low RCS antenna due to its exceptional performance as compared to CB_1 and CB_2. The hybrid MM is organized in chessboard configuration, comprises of splitted square and ring shaped MM unit cell. The results show that proposed antenna gives substantially out of band RCS reduction from 6 to 18 GHz and the proposed antenna has a lower RCS than the reference antenna. Proposed antenna attains wideband bandwidth around 7.4 GHz (ranging 2.0‐4.4 GHz, 7.8‐9.1 GHz, and 14.3‐18 GHz). The maximum reduction of −30.1 dBsm at 16.4 GHz is achieved in the hybrid MM structure impinged microstrip patch antenna. Finally, the fabrication and performance evaluation of MM loaded antenna is carried out. Moreover, measured results of the fabricated samples are closely matched with simulated results, which prove the effectiveness of the adopted approach for practical applications.

Circularly Polarized Antenna Array With Low RCS Using Metasurface-Inspired Antenna Units

In this work, a circularly polarized (CP) antenna array with low radar cross section property based on CP metasurface-inspired antenna units is proposed. The polarization conversion metasurface is utilized as the radiator of the antenna. The in-band and out-of-band scattering of the antenna array under normal incidence is reduced by the chessboard configuration of the antenna units. Meanwhile, good radiation characteristics are realized by utilizing the sequentially rotated feeding network. The antenna prototype is fabricated and measured. The measured results show good agreement with simulated results.

Multifunctional Transparent Electromagnetic Surface Based on Solar Cell for Backscattering Reduction

Advanced electromagnetic (EM) surfaces, namely, metasurfaces, are designed for multifunctional purposes. A glass material with a chessboard configuration is exploited to realize nonabsorbing coating for backscattering reduction. Simultaneously, a solar cell is implemented above the metallic target for light energy harvesting using the transparency feature of the coat. Therefore, two separated aims are obtained in one structure using the plexiglass material and mono solar cell. Initially, the EM wave interactions with both materials are determined. Then, by the use of the wave interactions and scattering theory, two different surfaces are analytically investigated with the aim of transparent backscattering reduction cover. Next, an optimization algorithm is employed to achieve the minimum reflection from the adjacent surfaces. To validate the design performance, a prototype is manufactured. The proposed chessboard cover with plexiglass material is numerically and experimentally analyzed and compared together, having an acceptable agreement. The experimental results indicate a 75% bandwidth for backscattering reduction. In addition, the proposed structure can give promising opportunities to enhance the scattering properties with simultaneous power harvesting, which could generate critical advantages for real-world applications.

Lightweight ultra-wideband radar cross section reduction structure using double-layer metasurfaces

In this paper, we propose the design of a lightweight RCS reduction structure using double-layer metasurfaces. The structure is composed of two layers of metasurfaces spaced by PMI foams. To extend the bandwidth, two unit structures are firstly designed to operating in two respective bands for circularly polarized (CP) waves, which are then combined to act as the unit structure of the double-layer metasurface. The metasurface is expected to operate in two continuous bands. Nevertheless, due to the couplings between the two unit structures, there is Fano resonance that prohibits merging of the two bands. To solve this problem, we tune the resonant frequency of the bottom unit structure to suppress the Fano resonance and obtain a merged band. The combined unit structure is employed as the element of chessboard configuration, which can reduce RCS by more than 10 dB in an ultra-wide band (4.5–16.5 GHz). We designed, fabricated and measured a lightweight prototype (the aerial density is 726 g m−2). Both the simulation and experiment result verify the design. This work provides an effective method of extending the operation band of RCS reduction without sacrificing the efficiency.

High-Gain Circularly Polarized Fabry–Pérot Patch Array Antenna With Wideband Low-Radar-Cross-Section Property

In this paper, we explore the adoption of a chessboard polarization conversion metasurface (CPCM) for constructing a low-radar-cross-section (RCS), high-gain circularly polarized patch array antenna. The proposed CPCM is used as the CPCMs’ chessboard configuration, which consists of adjacent two-layer substrates that have three metallic models. Low RCS is achieved by 180° (± 30°) reflection phase variations of two adjoining PCMSs. Gain enhancement is achieved by adopting a Fabry–Perot cavity constituted by a PCM and the antenna’s ground. The antenna with a CPCM that operates at X-/Ku-band, excited by the feeding network that is rotated sequentially, is measured and fabricated. The patch array antenna impedance bandwidth based on the PCM was measured as 3.3 GHz (9.5–12.8 GHz) with a 3-dB axial ratio bandwidth of 11.6% and a high gain of 13.4 dBiC (9.5–12 GHz), more than 2.5 dB higher when compared with a patch antenna without a PCM. In addition, the patch array antenna produced a useful wideband RCS decrease in the operational bandwidth from 9 to 13 GHz.

Wideband radar cross section reduction using a novel design of artificial magnetic conductor structure with a triple-layer chessboard configuration

A novel wideband three-layer chessboard-like structure is proposed to reduce the radar cross section (RCS) of the radar target. This configuration is composed of two artificial magnetic conductor (AMC) cells formed by two crossed ellipses with different sizes in two cells. A desired 180° ± 37° phase difference is achieved by combining these unit cells and the measured 10 dB RCS-reduction bandwidth is extensively broadened to more than 96% (from 8.11 to 23.32 GHz, covering X, Ku, and K bands for different radars) in comparison with the other works. This characteristic is obtained by carefully adjusting the positions of all resonances using the proper sizes for the ellipses and the proper dielectric constants and thicknesses for the three layers. Although, the proposed design has three layers with the overall thickness of 2 mm, it is still thinner than most of the recent related works. This low-profile structure is also cost-effective due to the fact that 60% of the overall thickness is formed by an air substrate. The proposed cells are designed, simulated, and fabricated in a chessboard-like configuration for both monostatic and bistatic RCSs. Simulations and measurements are in a good agreement, which shows the capabilities of the design.

Design of multi-band metasurface antenna array with low RCS performance**Project supported by the National Natural Science Foundation of China (Grant Nos. 61471389, 61701523, and 61671464).

In this paper, a multi-band metasurface (MS) antenna array with low radar cross section (RCS) performance is proposed and measured. Firstly, a 4 × 4 antenna array is composed of four 2 × 2 Jerusalem cross structure antenna arrays working at different frequency bands, which is aimed at enhancing the bandwidth effectively. Then, each antenna can be seen as a unit of MS in spite of adding the feeding structure. Based on phase cancellation principle, the MS is arranged into a chessboard configuration in order to realize wideband RCS reduction. Thus, excellent radiation and scattering characteristics are obtained simultaneously. Simulated and measured results indicate that this work provides a novel method to achieve bandwidth expansion as well as wideband RCS reduction of the antenna array.

Low RCS and broadband metamaterial‐based low‐profile antenna using PCM

In this study, a novel cross layout of polarisation conversion metamaterial (PCM) is investigated for the first time. Based on the principle of phase cancellation, the cross structure can reduce radar cross section (RCS) significantly over a wider band compared with the chessboard configuration. The low-profile metamaterial-based antenna is composed of the cross PCM structure and a driven patch sandwiched between the PCM patches and the ground plane. Simulated and measured results show that compared with the microstrip patch antenna, the proposed antenna can achieve a wider impedance bandwidth of 6.05-7.52 GHz (21.7%) and milder gain variation in the working band, while the monostatic RCS can be reduced over 5.8-18.0 GHz (102.5%).