Chessboard Configuration Research Articles

Reconfigurable polarization rotation surfaces applied to the wideband antenna radar cross section reduction

A reconfigurable polarization rotation surface (PRS) using chessboard-like geometry is introduced for the radar cross section (RCS) reduction of a Yagi-Uda antenna in this article. The reconfigurable PRS reflector can be switched between low-RCS PRS reflector and metal reflector. When the reconfigurable PRS reflector with ON-state diodes is used in the Yagi-Uda antenna, the antenna has a similar radiation characteristic compared with Yagi-Uda using metal reflector. The PRS reflector can be used to achieve a low-RCS characteristic reflector by chessboard configuration with OFF-state diodes. Finally, the status of RCS can be switched according to the working state of diodes. The results show that the radiation performance of the Yagi-Uda is preserved. The monostatic RCS of the Yagi-Uda using PRS reflector with OFF-state diodes can be reduced more than 25 dB.

Chessboard AMC Surface Based on Quasi-Fractal Structure for Wideband RCS Reduction

A chessboard artificial magnetic conductor surface based on the quasi-fractal structure is proposed for wideband radar cross-section (RCS) reduction. The chessboard configuration is formed by two different cells with 180° ± 37° phase difference over more than 90% frequency bandwidth. The quasi-fractal structure is utilized to achieve the wideband and compact characteristics. Monostatic and bistatic RCS of the proposed chessboard surface are analyzed, and the results are compared with those of equal-sized perfect electric conductor ground plane. Because the scattered fields of the chessboard surface are redirected toward four quadrants, a remarkable RCS reduction of 10 dB can be realized from 5.4 to 14.2 GHz. Measured results of the fabricated prototype satisfactorily agree with the simulated ones.

Low-Scattering Tri-Band Metasurface Using Combination of Diffusion, Absorption and Cancellation

In this paper, we proposed for the first time a novel mechanism to design a tri-band low-scattering metasurface. The radar cross section (RCS) reduction in the three operational bands relies on scattering diffusion, absorption, and scattering cancellation, respectively. The diffusion metasurface was realized by distributing scattering unit cells with different rotation angles. For the absorption, four units operating at different frequencies were combined to achieve a broadband absorption. The scattering cancellation was realized by arranging two out of phase elements in a chessboard configuration. The tri-band metasurface was constructed by directly combining the three metasurfaces in a single assembly. The simulated and measured results have a good agreement. The tri-band RCS reduction is well preserved up to 45° with polarization-independent performance. This paper provides an alternative approach to design the multi-band metasurface for stealth application.

Ultra-Wideband Low-RCS Circularly-Polarized Metasurface-Based Array Antenna Using Tightly-Coupled Anisotropic Element

A novel broadband circular-polarized array antenna with ultra-wideband low radar cross section (RCS) is proposed. The array is made up of $2\times2$ identically circular-polarized sub-arrays in a chessboard configuration. Furthermore, each sub-array consists of $2\times2$ tightly coupled metasurface-based elements with linear polarization. For radiation, each element is excited and fed with 90° phase shift between adjacent ones to perform broadband circular-polarized operation. For scattering, destructive phase difference is created in an ultra-wide band for orthogonally polarized incidence due to the anisotropic structure. Thus, a considerable ultra-wideband RCS reduction involving in-band and out-of-band is achieved based on energy cancellation. By this means, broadband circular-polarized radiation and ultra-wideband low RCS performance can be achieved in a synthesized design process. The prototype is fabricated and measured. A good agreement between measured and simulated results verifies the validity of our design method.

Integrated radiation and scattering performance of a multifunctional artificial electromagnetic surface.

In this paper, a multifunctional artificial electromagnetic surface (AEMS) with integrated radiation and scattering performance is proposed and realized. Different from previous AEMS designs that mainly focus on scattering performance, this AEMS design takes both radiation and scattering properties into consideration in the designing process. Inspired by the design concept of antenna, a feeding structure is added to each AEMS element to achieve radiation performance. Meanwhile, the concerned characteristics of AEMS elements are almost maintained. For achieving wideband low-scattering performance, two different kinds of AEMS elements are designed and arranged in a chessboard configuration. Simulated and measured results prove that our method offers an effective strategy to design multifunctional AEMS that achieve radiation and scattering performance simultaneously.

A Circularly Polarized High-Gain Antenna With Low RCS Over a Wideband Using Chessboard Polarization Conversion Metasurfaces

A new approach for the gain enhancement and wideband radar cross section (RCS) reduction of an antenna based on the chessboard polarization conversion metasurfaces (CPCMs) is proposed. Compared with the previous low-RCS antennas, high gain and wideband low RCS of a circularly polarized (CP) antenna are achieved simultaneously. The proposed CPCM is the chessboard configuration of the polarization conversion metasurfaces (PCMs), which is made up of adjoining two-layer substrates with three metallic patterns. Low RCS is realized by 180° (±30°) reflection phase variations between two neighboring PCMs. Gain enhancement is achieved by employing a Fabry-Perot cavity, which is constructed by the PCM and the ground of the antenna. The antenna with CPCM operating at the $X$ -band, excited by a sequentially rotated feeding network, is fabricated and measured. Simulated and measured results show that the left-hand CP gain of the antenna with CPCM is at least 3 dB higher than that of the reference antenna from 8.5 to 9.5 GHz and the monostatic RCS is effectively reduced from 6 to 14 GHz.

Ultra-wideband RCS reduction using novel configured chessboard metasurface**Project supported by the National Natural Science Foundation of China (Grant Nos. 61372034 and 61501499).

A novel artificial magnetic conductor (AMC) metasurface is proposed with ultra-wideband 180° phase difference for radar cross section (RCS) reduction. It is composed of two dual-resonant AMC cells, which enable a broadband phase difference of 180°±30° from 7.9 GHz to 19.2 GHz to be achieved. A novel strategy is devised by dividing each rectangular grid in a chessboard configuration into four triangular grids, leading to a further reduction of peak bistatic RCS. Both full-wave simulation and measurement results show that the proposed metasurface presents a good RCS reduction property over an ultra-wideband frequency range.

Gain Enhancement and RCS Reduction for Patch Antenna by Using Polarization-Dependent EBG Surface

A novel antenna design is proposed to enhance the gain and reduce the radar cross section (RCS) of a patch antenna by using metamaterial surface. A polarization-dependent metamaterial surface composed of blocks of slotted electromagnetic bandgap (EBG) structures are adopted in this letter. The layout pattern of the slotted EBG elements is designed to enhance the gain of the antenna. Chessboard configuration is further equipped for scattering cancellation. The induced currents on the EBG are studied, resulting in the mechanism of the gain enhancement by the EBGs clearly explained for the first time. This enables the strategy of designing a high-gain and low-RCS antenna by using EBGs. Full-wave simulations validate that high gain in the operating frequency band and low-RCS in a broad frequency band for normal incidence are achieved by the proposed antenna.

Wideband radar cross‐section reduction by AMC

A new planar wideband chessboard structure is designed to reduce the radar cross-section (RCS) of an object. This proposed chessboard configuration is composed of two different artificial magnetic conductor (AMC) tiles. One of these tiles is formed by saltire arrow unit cells, whereas the other one is formed by four E-shaped ones. A 180° ± 30° phase difference between these tiles achieved by precise design of the AMC unit cells of more than 9.4–23.28 GHz (85%) reduces the RCS by more than 10 dB. The fabricated board results show very good agreement with the simulated ones, which verify the ability and capability of the proposed structure.

Wideband RCS Reduction of a Slot Array Antenna Using Polarization Conversion Metasurfaces

A new approach to reducing the monostatic radar cross section (RCS) and preserving the radiation characteristics of a slot array antenna by employing polarization conversion metasurfaces (PCMs) is presented in this communication. The PCM is arranged in a chessboard configuration consisting of fishbone-shaped element. It is placed on the surface of the slot array antenna. The characteristics and mechanism of the RCS reduction are analyzed. Simulated and experimental results show that the monostatic RCS reduction band of the antenna with PCM ranges between 6.0 and 18.0 GHz for normally impinging both $x$ - and $y$ -polarized waves. The radiation characteristics of the antenna are well preserved simultaneously in terms of the impedance bandwidth, radiation patterns, and realized boresight gains.

A novel combinatorial triangle‐type AMC structure for RCS reduction

ABSTRACTA novel combinatorial triangle‐type artificial magnetic conductor (AMC) structure for radar cross section (RCS) reduction is presented in this article. The AMC part in conventional chessboard configuration is replaced with four triangle‐type AMC parts, so that the power can be transferred into more directions leading to the peak scattered field reduction. A simplified model is constructed to analyze the behavior of the proposed structure. The simulated results show that the peak value is reduced by more than 5 dB compared with the conventional chessboard configuration and the bistatic RCS is below −10 dB in a wide angular range from theta = −25° to 25°. Moreover, measurement of the monostatic RCS for the proposed structure is also conducted. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:2728–2732, 2015

Wideband RCS reduction and gain enhancement microstrip antenna using chessboard configuration superstrate

ABSTRACTA novel design for wideband radar cross section (RCS) reduction and gain enhancement microstrip antenna is proposed. Two 180° phase difference and modified artificial magnetic conductor cells are utilized to combine chessboard configuration superstrate (CCS). The bottom side of CCS is etched slot and exploited to construct Fabry–Perot resonance cavity with ground plane of a microstrip antenna. The CCS can enable the primary antenna to obtain gain enhancement and RCS reduction simultaneously. Measured results show that the proposed antenna gain is enhanced by about 4.8 dB at 9.6 GHz and its 3 dB gain enhancement bandwidth is from 9.1 to 10.5 GHz. The half power beamwidth is suppressed from 101° to 12° in E‐plane, while it is only 14° in H‐plane, decreased by about 75° compared with the primary antenna. Meanwhile, the antenna RCS is dramatically reduced in a broad frequency range from 8.0 to 14.0 GHz, which contains the operation band of the proposed antenna. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:1738–1741, 2015

Wideband RCS Reduction of a Microstrip Antenna Using Artificial Magnetic Conductor Structures

A design approach aimed at reducing the radar cross section (RCS) of microstrip antenna in wide frequency band is proposed. First, two different artificial magnetic conductor (AMC) unit cells are designed to obtain 180 <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$^\circ $</tex></formula> ( <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$ \pm 30^\circ $</tex></formula> ) reflection phase difference over broadband frequency range. Then, chessboard configuration is structured with the two AMC unit cells and is applied to a microstrip antenna for RCS reduction. The simulated results indicate that the proposed antenna possesses remarkable RCS reduction from 8.0 GHz to 20.0 GHz for both polarizations, covering the working band of the original antenna. The maximum reduction is 31.9 dB. Moreover, the radiation performance of the antenna has been well kept. Measured results of the fabricated prototype are in good agreement with the simulations.

Design of Talbot array illuminators

We present a general approach to design Talbot array illuminators. In both one-dimensional and two-dimensional cases, a general analytical form is given for the conventional Talbot array illuminators. The proposed form is valid for every fractional Talbot distance. Furthermore, we extended our approach to various topologies of the bright spots in the replay field. Several examples of particular topologies, such as the chessboard configuration, are discussed. In addition, more complex configurations are considered and a useful design technique is proposed.

Ground states of the spinless Falicov-Kimball model.

We present some exact results for the ground states of the Falicov-Kimball model outside the symmetry point. Three ion configurations have been considered: the chessboard configuration and the completely empty and the fully occupied configurations. Using a method based on Tchebycheff-Markov inequalities, we determine domains in the plane of chemical potentials ${\ensuremath{\mu}}_{e}$ and ${\ensuremath{\mu}}_{i}$, where these configurations are ground states.