Radar Cross Section Reduction Performance Research Articles

Resonance phase and geometric phase integrated diffusion metasurface for broadband scattering control

In this paper, we demonstrate a binary diffusion metasurface with a broadband radar cross section (RCS) reduction performance based on the integration of resonance and geometric phase manipulation. The working principle of such a metasurface was investigated and the general criterion for the electromagnetic (EM) responses of the meta-atom was derived. In particular, we deployed a split metallic ellipse ring with a beam along the short axis and its counterpart with a 90° inclined angle as the binary elements to construct the diffusion metasurface. EM responses of the proposed anisotropic meta-atom were explored in the framework of the equivalent circuit model. The inherent resonance phases of the meta-atom along its two symmetric axes were adjusted by changing its structural parameters. Then, we integrated the manipulation of the resonance phase and geometric phase together and designed a metasurface that can achieve broadband specular RCS reduction (more than −10 dB) from 4.3 GHz to 16.5 GHz. The RCS reduction performance of the metasurface is polarization-independent and shows a certain degree of stability under oblique incidence. For verification, a prototype with optimized structural parameters was fabricated and the measured results coincide well with the simulated results. Our work provides a convenient approach to realize a binary diffusion metasurface for the purpose of broadband RCS reduction.

Modulating dielectric loss of mesoporous carbon fibers with radar cross section reduction performance via computer simulation technology

Mesoporous carbon fibers, a kind of light weight microwave absorbing material, are prepared by electrospinning, through which the pore structure and microwave absorbing properties are influenced by the addition of tetraethyl orthosilicate.

A metasurface design method for dual wide band radar cross section reduction

Metasurface has attracted much attentions due to its ability of flexible manipulation of electromagnetic wave. However, the metasurface is limited to the single operating band and poor design generality when it is used for radar cross section (RCS) reduction. In this paper, a stacked metasurface design method has been developed to flexibly achieve dual wide band RCS reduction. Two subarrays with polarization conversion characteristic are firstly designed to operate in two wide bands, respectively. Then a low-pass frequency selective surface (FSS) is developed and sandwiched between two metasurface subarrays to achieve a subarray with the dual-band polarization conversion performance. With the arrangement of the dual-band subarray into a 2×2 array in a rotation way according to the polarization cancellation, the resultant metasurface structure has two −10 dB RCS reduction bands covering 6.6-12.7 GHz and 27.8-38.1 GHz. The designed prototype is fabricated and measured. The simulation and measurement results are given to demonstrate the good dual-band RCS reduction performance.

Hybrid-phase approach to achieve broadband monostatic/bistatic RCS reduction based on metasurfaces

In this paper, we propose an approach to design metasurfaces to realize superior performance for monostatic and bistatic radar cross section (RCS) reduction within a wide bandwidth. By engineering four subarrays to exhibit different hybrid focusing-linear phases within a metasurface, nearly uniform diffusive scattering can be inherently guaranteed. As an illustration, we design and fabricate a proof-of-prototype metasurface and experimentally demonstrate its wave-diffusion performances. Numerical and experimental results both show that the thin metasurface enables a monostatic/bistatic 10 dB RCS reduction over a broad bandwidth ranging from 7.2 to 17.2 GHz. In addition, more than 10 dB RCS reduction performance is preserved within a band of 7.8 ∼ 14.2 GHz even for off-normal incidence up to 60°. Our approach features broadband, polarization insensitive, wide incident angles and easy design without time-consuming optimization, promising great potentials in applications of low-scattering stealth.

Design of a Low Scattering Metasurface for Stealth Applications.

The design of a metasurface with low radar cross section (RCS) property is presented in this paper. The low scattering of the metasurface is achieved by applying the artificial magnetic conductor (AMC) unit cells in three different configurations. Two different AMC unit cells with an effective phase difference of 180 ± 37° are first designed to analyze the out of phase reflection in a wideband frequency range from 5.9 to 12.2 GHz. Then, the unit cells are placed in a chessboard-like configuration, newly constructed rotated rectangular-shaped configuration, and optimized configuration to study and compare the RCS reduction performance. All designs of the metasurface with different configurations show obvious RCS reduction as compared with the metallic plate of the same size. However, the relative bandwidth of the optimized metasurface is larger than the chessboard-like configuration and rotated rectangular-shaped configuration. To certify the results of the simulations, the metasurface with the optimized configuration is fabricated further to measure the RCS reduction bandwidth. The measured results are in good accordance with the simulated results. Therefore, the proposed metasurface can be a good option for applications where low RCS is desirable.

Reducing RCS of Patch Antennas via Dispersion Engineering of Metamaterial Absorbers

In this paper, a low radar cross section (RCS) patch antenna is proposed, which is realized by engineering dispersion property of metamaterial absorbers (MAs). The dispersion curve of the MA consists of a weak linear regime with low insertion loss and an asymptotic nonlinear regime with strong absorption. By changing geometric parameters, the dispersion property of the MA can be engineered, so that the cutoff frequency is shifted freely, as well as the strong absorption band being changed. Thus, if the cutoff frequency of the MA is very close to the upper bound frequency of a patch antenna, the patch antenna will obtain polarization-independent low-RCS property out-of-band or in-band cross-polarized and out-of-band copolarized low-RCS properties by replacing the radiation patch with the modulated MA. For verification, a ${C}$ -band patch antenna with RCS reduction performance in ${X}$ -band is designed, fabricated, and measured. Both the simulated and measured results agree well and verify that the antenna achieves average gain about 5 dB in 7.2–7.7 GHz. To assess the RCS reduction performance of the proposed patch antenna, we fabricated a $5 \times 5$ antenna array. The measured results indicate that monostatic RCS of the array is decreased by more than 10 dB in the entire ${X}$ -band for copolarized and cross-polarized wave normal incidence than the metallic plate with the same area.

A Novel Reflectarray Antenna with Reduced RCS

A novel frequency selective surface (FSS) configuration in the reflectarray antenna is proposed for reduction of radar cross section (RCS) level in this work. Double-layer FSS structure is located behind the reflectarray antenna as a ground. A 9 9 elements FSS with variable size patches has same geometry with the reflectarray antenna. The RCS reduction performance of reflectarray antenna both ground plane backed and FSS backed is compared. The results of simulation are obtained by using CST Microwave Studio. The simulation results show that RCS level of FSS backed reflectarray antenna is reduced both in-band (8-12 GHz) and out-of-band (2-7 GHz and 13-18 GHz). In the literature, RCS reduction of reflectarray antenna with FSS structure has only been achieved out-of-band. Furthermore, the gain and radiation performance of the ground plane backed reflectarray antenna and FSS backed reflectarray antenna are compatible with each other.

Metasurface base on uneven layered fractal elements for ultra-wideband RCS reduction

A novel metasurface based on uneven layered fractal elements is designed and fabricated for ultra-wideband radar cross section (RCS) reduction in this paper. The proposed metasurface consists of two fractal subwavelength elements with different layer thickness. The reflection phase difference of 180° (±37°) between two unit cells covers an ultra-wide frequency range. Ultra-wideband RCS reduction results from the phase cancellation between two local waves produced by these two unit cells. The diffuse scattering of electromagnetic (EM) waves is caused by the randomized phase distribution, leading to a low monostatic and bistatic RCS simultaneously. This metasurface can achieve -10dB RCS reduction in an ultra-wide frequency range from 6.6 to 23.9 GHz with a ratio bandwidth (fH/fL) of 3.62:1 under normal incidences for both x- and y-polarized waves. Both the simulation and the measurement results are consistent to verify this excellent RCS reduction performance of the proposed metasurface.

Scattering reduction of perfectly electric conductive cylinder by coating plasma and metamaterial

This paper presents the radar cross section (RCS) reduction of scattering of perfectly electric conductive (PEC) cylinder coated with plasma and metamaterial by finite-difference time-domain (FDTD) method. Two coating schemes of the cylinder were studied to find better RCS reduction performance. One is to put the plasma layer at the outside and the other is to put the metamaterial layer outside. The influence of plasma's thickness and collision frequency was studied. The calculation results show that in the low frequency (f = 3 GHz), the target realizes a considerable RCS reduction in a wide bistatic angular range. In the high frequency (f = 18 GHz), the reduction performance is not as good as low frequency. The results also show that by the effect of plasma and metamaterial, the reduction performance is much better than coated with plasma.

Random Combinatorial Gradient Metasurface for Broadband, Wide-Angle and Polarization-Independent Diffusion Scattering

This paper proposes an easy, efficient strategy for designing broadband, wide-angle and polarization-independent diffusion metasurface for radar cross section (RCS) reduction. A dual-resonance unit cell, composed of a cross wire and cross loop (CWCL), is employed to enhance the phase bandwidth covering the 2π range. Both oblique-gradient and horizontal-gradient phase supercells are designed for illustration. The numerical results agree well with the theoretical ones. To significantly reduce backward scattering, the random combinatorial gradient metasurface (RCGM) is subsequently constructed by collecting eight supercells with randomly distributed gradient directions. The proposed metasurface features an enhanced specular RCS reduction performance and less design complexity compared to other candidates. Both simulated and measured results show that the proposed RCGM can significantly suppress RCS and exhibits broadband, wide-angle and polarization independence features.