Radar Cross Section Simulation Research Articles

Achieving high-efficiency and broad bandwidth with low filler loading for hierarchical Fe3O4/Co-MOF absorbers

Metal-organic frameworks (MOFs) with intrinsic porosity and high specific surface area have aroused broad interests as a promising electromagnetic (EM) absorbing material. However, the introduction of magnetic components in MOFs has remained as a formidable obstacle for subsequent development. Herein, Fe3O4/Co-MOF composites were fabricated via a facile and scalable co-precipitation process. The microstructure and morphology of the composites were characterized and the combination of hollow Fe3O4 and Co-MOFs was found to contribute towards the dissipation of incident waves due to the magnetic-dielectric synergistic effect. Impressive microwave absorption ability was obtained with a minimum reflection loss of –56.1 dB over a qualified bandwidth (7.9 GHz) at 2.0 mm. Moreover, the radar cross section simulation further confirmed the effective suppression of radar wave scattering using Fe3O4/Co-MOF composites. This study provides a versatile strategy for designing magnetic-dielectric composites based on MOFs as effective and broadband microwave absorbers.

Facile synthesis of heterogeneous Co/MnO@C nanocapsules with dual-cores: Achieving strong and broadband microwave absorption by magnetic-dielectric synergy

Nowadays, constructing a high-efficiency microwave absorber with strong absorption strength and wide absorption bandwidth is urgently demanded for practical applications in the microwave absorption (MA) field. In this work, the Co/MnO@C nanocapsules with magnetic/dielectric dual cores were fabricated through in-situ carbon reduction of the MnCo2O4 nanoparticles. The effects of calcination temperature on electromagnetic parameters and MA ability are investigated in detail. Notably, the sample obtained at 900 ℃ exhibits the minimum reflection loss (RL) value of −97.5 dB at 10.6 GHz, while the effective absorption bandwidth (EAB, RL ≤ −10 dB) is up to 8.1 GHz (9.9–18 GHz) at 2.1 mm thickness, covering half of X-band and whole Ku-band. The excellent MA performance is attributed to the core–shell structure, multiple heterogeneous interface polarizations, synergistic effects between magnetic and dielectric components, as well as promoted impedance matching. Importantly, the electric and magnetic field distributions are simulated by ANSYS software, and the polarization and magnetic coupling behaviors are deeply analyzed. The simulated radar cross-section (RCS) results confirm that the optimized Co/MnO@C nanocapsules can efficaciously attenuate more electromagnetic energy in the practical environment. It is believed that the as-prepared Co/MnO@C nanocapsules are considered to be promising high-efficiency microwave absorbers for practical applications.

Heterostructure tailoring of carbon nanotubes grown on prismatic NiCo clusters for high-efficiency electromagnetic absorption

The employment of electromagnetic (EM) absorbers integrating elaborate architecture, enhanced microwave absorption and multifunctional features remains a formidable challenge in practical applications including military stealth and incoming 5G electronic information era. Herein, a novel microwave absorber has been fabricated by in-situ growing carbon nanotubes (CNTs) on the prismatic nickel–cobalt (NiCo) clusters derived from Ni-Co layered double hydroxides (NiCo-LDH) via catalytic carbonization of ethyl acetate. The NiCo/CNTs composites with highly porous texture could provide sufficient open space to balance the impedance and introduce magnetic loss mechanism. Accordingly, the absorbers achieved remarkable EM absorption performance with a minimum reflection loss of –46.2 dB at 1.5 mm and broad bandwidth of 5.8 GHz owing to synergistic magnetic-dielectric effects and distinct structural merits. The NiCo/CNTs absorber manifests superior radar wave attenuation by the radar cross section simulation and density functional theory (DFT) was also performed to elucidate the potential mechanisms of the heterostructure formation and performance enhancement in the NiCo/CNTs composites. This work is expected to provide new insights or inspirations to modulate EM properties by rationally designing heterostructure for the elimination of severe EM pollution.

Stealthy Configuration Optimization Design and RCS Characteristics Study of Microsatellite

Firstly, the radar cross section (RCS) test results of the stealthy microsatellite of TianXun-1(TX-1) in the anechoic chamber are compared with the RCS numerically simulated by the physical optics method, and the accuracy of the physical optical method is verified. On this basis, in order to improve the radar stealth performance of the microsatellite, a satellite stealth configuration optimization design method is proposed with the multi-prismatic stealth configuration of TX-1 as the initial configuration, and two olive stealth satellite configurations are obtained. By comparing the RCS simulation and radar detection probability of the optimized Olive-A and Olive-B satellite stealth configurations in multiple directions, it is demonstrated that the stealth performance of the Olive-B configuration is better. Finally, the anechoic chamber test is conducted on the metallic Olive-B model, and the test results show that the test results and simulation results of Olive-B are in good agreement, which again verifies that the stealth performance of Olive-B is better than that of TX-1 and Olive-A.

Bi-semiconductor heterojunction Cu9S5@VO2 microspheres with morphology regulation as broadband high-performance electromagnetic wave absorber

The development of heterojunction composite materials with excellent electromagnetic wave absorption performance is emerging as an effective means to address the hazardous electromagnetic waves. Here, two types of Cu9S5@VO2 microspheres with different morphologies were designed. The Cu9S5@VO2 microspheres were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, and vector network analyzer. Results show that the minimum reflection loss (RLmin) of unique lamellar-flower Cu9S5@VO2 sphere reaches −56.98 dB, and the wide effective absorption bandwidth (EAB) is 6.88 GHz at only 2.5 mm thickness due to the synergistic effect of multiple loss mechanisms. Radar simulated radar cross section (RCS) results show a reduction of 16.56 dBm2. The design engineering of the phase interface on the material surface can functionalize the material surface properties, introduce lattice defects and polarization behavior, and improve the microwave absorption performance of the material. This work enriches the use of copper sulfide-based functional composites in microwave absorption with high-performance microwave absorbers by designing microscopically controllable, simple processes and heterojunction design.

Preparation of Ni/C composite microwave absorbers with high performance by controlling nickel source

Three Ni/C composites with different morphologies were prepared by changing nickel salt using a hydrothermal method and high-temperature pyrolysis. Results show that material defects, nitrogen doping, heterointerface, conductive network, and magnetic effect optimize impedance matching, resulting in the synergistic effect of conductivity loss, polarization loss, multiple scattering, and magnetic loss. The reflection loss of the sample prepared using nickel nitrate is − 44.2 dB at 11.84 GHz and 2.4 mm thickness, and the effective absorption bandwidth is 5.2 GHz. In addition, radar cross section simulation demonstrates the excellent performance of the material in practical applications. Thus, the sample prepared using nickel nitrate is a candidate material for radar stealth and electromagnetic wave absorption.

Multifunctional Nd2O3/CNFs Composite for Microwave Absorption and Anti-Corrosion Applications

To improve the limitations of traditional microwave absorbing materials (MAMs), such as high density and narrow absorption bandwidth, neodymium oxide/carbon nanofiber (Nd2O3/CNF) composites were successfully prepared by electrospinning technology combined with a high-temperature carbonization process. The three-dimensional network structure of CNFs provides a path for conducting electromagnetic waves, and its porous structure also increases the multiple reflections of electromagnetic waves in the composite fibers, which significantly attenuates the energy of electromagnetic waves. Additionally rare-earth elements have a unique electronic arrangement on the 4f electron layer. The addition of Nd2O3 can turn the dielectric constant of Nd2O3/CNF and optimize the impedance matching. Also, Nd2O3 nanoparticles (Nd2O3–NPs) resulted in numerous of heterojunction surfaces and introduced the magnetic loss mechanism. Under the combined action of the double loss mechanism, the minimum reflection loss of Nd2O3/CNF composite fiber is −66.7 dB at 9.36 GHz, and the effective absorption bandwidth is 4.4 GHz (7.68–12.08 GHz). The radar cross section simulation results also prove that the composite fibers exhibit strong consumption of electromagnetic waves. Additionally, the excellent flexibility and anticorrosion properties of the composite fibers make them satisfy the multifunctional requirements of MAMs.

A Fast Method for SBR-Based Multiaspect Radar Cross Section Simulation of Electrically Large Targets

In this letter, a novel method is proposed to rapidly simulate the multiaspect monostatic radar cross section of electrically large complex targets based on the shooting and bouncing ray method (SBR). The core of the method is to use the inheritance of the illumination to determine the illumination of the target surface, rather than independently simulating for each required aspect angle as in the traditional SBR method. To achieve this, the illumination variation on the target surface is summarized and the genetic illumination information is defined. The error of the method is also discussed and the multiple precalculation solutions is proposed to control the error. Different simulation examples show our method has good general applicability and great efficiency. Finally, a realistic aircraft is simulated at 10 GHz using the multiple precalculation solution.

Generalized Radar Range Equation Applied to the Whole Field Region.

Most terahertz (THz) radar systems can only work in the near-field region, because the THz source power is limited and the size of the target scattered near field is up to tens of kilometers. Such conditions will result in the conventional radar range equation being unsuitable. Therefore, the near-field radar cross section (RCS) formula is given according to the numerical simulation on different targets. By modifying the parameters in the near field, including the gain of radar antennas and the RCS of targets, the generalized radar range equation is proposed. The THz radar working efficiency in the whole range and the simulation of the near-field RCS simulation model were employed to validate its effectiveness. Through comparison with the radar range equation, it can be concluded that the calculation results of the proposed equation are smaller in the near field, and the outcomes in the far field are identical. The proposed generalized radar range equation can be applied to the whole radiation area including the near field and the far field. Furthermore, more complicated real targets are calculated according to the generalized radar range equation and it can be extended from the submillimeter wave band to a much wider band range. Finally, the near-field radar theory is established, which shows its potential application to the radar cross section estimation in the extremely high frequency and fine design of THz radar systems.

The Effect of Turbulence on Dynamic Radar Cross Section of Chaff Clouds

Objective: This research reports the effect of turbulence on the dynamic Radar Cross Section (RCS) of chaff cloud. In the era of modern warfare technologies, most efficacious electronic countermeasure employed by the armed forces of various major powers is the Chaff. Chaff is based on the expulsion of numerous electrical dipoles of different length to cover the broad spectrum of radar frequency. This mechanism helps in deceiving the enemy missile by producing the required RCS. RCS of chaff cloud is a dynamic entity and rely on several aerodynamic factors. Methodology: Effects of turbulence on dynamic RCS are studied using Ansys Fluent for aerodynamic blooming simulation and Ansys HFSS for simulation of RCS of the bloomed chaff cloud. Findings: The subject of the paper corresponds to the significant effect of turbulence on the expeditious blooming of chaff cloud. The RCS of turbulent flow was higher by 1.5dBsm to 2.5dBsm for 50msec. The turbulence effect has reduced the blooming time of chaff filaments in the range of 25msec - 50msec. Novelty: Turbulence plays important role in faster blooming of chaff cloud and achieving minimum threshold RCS required for deception of RF seeker missiles. Keywords: Chaff; RCS; Turbulence; Modelling and Simulation

Analysis of a Dynamic Calibration Target for Through-Wall and Through-Rubble Motion Sensing Doppler Radar

Through-wall and through-barrier motion-sensing systems are becoming increasingly important tools to locate humans concealed behind barriers and under rubble. The sensing performance of these systems is best determined with appropriately designed calibration targets, which are ones that can emulate human motion. The effectiveness of various dynamic calibration targets that emulate human respiration, heart rate, and other body motions were analyzed. Moreover, these targets should be amenable to field deployment and not manifest angular or orientation dependences. The three targets examined in this thesis possess spherical polyhedral geometries. Spherical geometries were selected due to their isotropic radar cross-sectional characteristics, which provide for consistent radar returns independent of the orientation of the radar transceiver relative to the test target. The aspect-independence of a sphere allows for more accurate and repeatable calibration of a radar than using a nonspherical calibration artifact. In addition, the radar cross section (RCS) for scattering spheres is well known and can be calculated using far-field approximations. For Doppler radar testing, it is desired to apply these calibration advantages to a dynamically expanding-and-contracting sphere-like device that can emulate motions of the human body. Monostatic RCS simulations at 3.6 GHz were documented for each geometry. The results provide a visual way of representing the effectiveness of each design as a dynamic calibration target for human detection purposes.

The controllable porous structure and s-doping of hollow carbon sphere synergistically act on the microwave attenuation

Currently, the development of high-efficiency electromagnetic wave (EMW) absorbing materials has received close attention. Due to unique composition and structure, porous hollow carbon spheres (PHCSs) have been extensively studied in the EMW absorption field. In order to obtain the regulated EMW absorber, in the present study, sulfur was successfully doped into the PHCS by hydrogen peroxide etching and high temperature vulcanization. By fixing the amount of sulfur doped and the etching time, the micro-structure of the product could be effectively controlled, and the corresponding electromagnetic parameters would also change accordingly. The optimized sulfur-doped porous hollow carbon sphere (SPCHS) had the minimum reflection loss (RL) value of −27.2 dB, and the effective bandwidth of 4.76 GHz. More importantly, the best effective bandwidth (EAB, RL < −10 dB) could reach 6.72 GHz (11.28–18 GHz) at the thickness of 2.25 mm. It should be pointed out that the sample filling ratio was only 5 wt% in the paraffin matrix. In addition, when the incidence θ reached −60°, the maximum reduction of radar cross section (RCS) was −21.9 dB m2. The convenient and efficient RCS simulation provided reliable support for the practical application of SPHCS materials in the field of EMW absorption.

Fe nanoparticles decorated in residual carbon from coal gasification fine slag as an ultra-thin wideband microwave absorber

Microwave absorbing materials are widely used in the defense and telecommunications industries, as means for enhancing battlefield penetration rate and improving the protection of precision instruments. The magnetic-dielectric Fe@ residual carbon from coal gasification fine slag (Fe@RC) nanocomposites were fabricated via a chemical coprecipitation and thermal annealing method, in which involve a reduction process from the Fe3O4 to Fe metal. The structure, morphology, compositions and electromagnetic parameters of the as-prepared Fe@RC materials were characterized. The obtained nano-micro scale Fe@RC shown adjusting electromagnetic parameters and outstanding microwave absorbability. The optimized reflection loss value of −47.1 dB was attained at 5.5 GHz for Fe@RC, and the effective bandwidth is 5.3 GHz (12.4–17.7 GHz) at a matching thickness of 1.5 mm. Benefit from good impedance match, special space architecture and synergistic effect between the dielectric loss from RC component and magnetic loss from Fe component, this Fe@RC materials are expected to be a potential microwave absorber. The simulated radar cross section (RCS) results prove that the Fe@RC can efficaciously reduce the microwave scatterings of the perfect electric conductor substrate at different degrees in C-, X-, and Ku-bands via adjusting the Fe@RC coating thickness. The low-cost carbon-based magnetic nanocomposites display an ultra-thin wideband microwave absorption ability and high RCS reduction performance, promoting resource utilization of the RC from coal gasification fine slag.

RCS 모의 데이터를 활용한 기동에 따른 레이다 성능 분석

During radar operation, changes in the radar cross section (RCS) of a target have an adverse effect on the radar detection performance. In particular, the RCS of a target with high maneuvering characteristics can be changed rapidly. Therefore, a precise prediction of the RCS change is essential for satisfactory radar detection performance. In this study, a modeling and simulation (M&amp;S) tool was developed for the estimation of radar detection performance. The M&amp;S tool comprises a radar model, target model, and wave propagation model. In particular, pre-obtained RCS simulation data were utilized to consider the effect of the RCS change of the target. Using the developed tool, the RCS based on the relative attitude is extracted from the RCS simulation data and the RCS processed data using the moving average method. The M&amp;S model is verified by comparing the two test results with the radar received signal power. Consequently, we verified that when using the RCS manufacturing data, the signal power is more similar to the test data than the other RCS simulation methods. It is expected that the radar performance on the high-maneuvering target can be estimated using the developed M&amp;S tool.

Effect of Driving Frequency on Reduction of Radar Cross Section Due to Dielectric-Barrier-Discharge Plasma in Ku-Band

This study investigates the effect of driving frequency on the ability of a dielectric barrier discharge (DBD) plasma to reduce the radar cross section (RCS) in the Ku -band. Analysis based on the Drude model suggests that the electron density of the plasma will increase with the driving frequency, implying that the plasma will be more effective in terms of RCS reduction. Experimental results based on a multifingered DBD generator reveal that an RCS reduction of up to 4.1 dB is achieved at 18 GHz, which is a 1.3 dB increase due to increasing the driving frequency from 1 to 2 kHz. Finally, the electron density, which is extracted by fitting the simulated RCS results, increased by as much as approximately 330% due to the increase in the driving frequency from 1 to 2 kHz. As the driving frequency increases, the frequency of collision between plasma particles increases. Therefore, the ionization of gas molecules is enhanced, resulting in a higher electron density. The experimental results also suggest that enhancement in the RCS reduction is larger when the electric field intensity between the two electrodes of the DBD generator is greater. As a result, the plasma becomes electromagnetically more lossy and is more effective for reducing the RCS. Experimental results are provided and analyzed based on the electromagnetic parameters used for modeling the plasma.

Three-Dimensional Ordered Mesoporous Carbon Spheres Modified with Ultrafine Zinc Oxide Nanoparticles for Enhanced Microwave Absorption Properties

HighlightsThree-dimensional ordered mesoporous carbon spheres modified with ultrafine zinc oxide nanoparticles are successfully prepared.The microwave absorbing performance of zinc oxide/carbon nanocomposites can be controlled through regulating ratio of zinc oxide nanoparticles.Electromagnetic simulation of radar cross section on a complicated groove structure demonstrates the microwave absorbing ability of the carbon based nanocomposites.

Potential performance of polarimetric reference function of SAR data processing by coherent target decomposition

Significant employment of polarimetric synthetic aperture radar (SAR) is the classification of the Earth’s surface, which includes several processing algorithms, labelling, and representation options. This paper investigated the potential performance of the polarimetric reference function in SAR data processing to apply in coherent decomposition. The proposed methodology employed the simulated radar cross section of dihedral and trihedral corner reflector under a SAR geometry using physical optics (PO) and geometrical optics (GO) to produce the polarimetric reference function for azimuth compression in the processing of SAR data. The Pauli and the Krogager decompositions processed the compressed SAR data to investigate the effect and performance of the polarimetric reference function. The colour clustering results based on k-mean clustering algorithm could deliver more related scattering characteristic. The image pixel classification was strongly associated with the polarimetric reference function in processing step. These findings indicated that the obtained decomposition and clustering results could provide a better performance in visual impact and quantitative evaluation according to the decomposition term, as well as its physical interpretation.

Radar cross section analysis of unmanned aerial vehicles using predics

In this study, a quantitative radar cross section (RCS) analysis of different unmanned aerial vehicle (UAV) models were accomplished by means of a series of RCS simulations. The simulations were carried out by high-frequency RCS simulation and analysis tool called PREDICS. To quantify the RCS features of the UAV model, both the anglevariation and frequency-variation simulations for all polarization excitations were performed. The results of the simulations suggested that RCS values were dramatically varying with respect to look angle with some special angles providing the large values of RCS. Generally, the RCS values of the UAV model was increasing with frequency as expected. A quantitative radar detection range analyses were also accomplished to assess the visibility of both the military-type and civil-type UAV models. The outcome of these studies has suggested that large-size UAV model can be easily detected by a high-sensitive radar on the ranges of tens of kilometers while these numbers reduce to a few kilometers for a civilian UAV model that is much smaller than the its military counterpart.

Approach to Control Permittivity and Shape of Centimeter-Sized Additive Manufactured Objects: Application to Microwave Scattering Experiments

Controlling the electromagnetic properties of dielectric objects is demanded in microwave applications such as radar cross section (RCS) studies, metamaterial design, and antennas prototyping. Additive manufacturing has made the fabrication of desired shapes easier, but there is still room for improvement in controlling the permittivity. This article proposes a novel approach to control the permittivity of 3-D printed objects, in particular the ones with low permittivity contrasts. The effective permittivity is set by locally varying the material density. The object is first meshed using tetrahedral meshing software. Then its air percentage is controlled by adjusting the diameter of cylinders, which are positioned at each edge of the mesh. By tuning the volume fraction, one can achieve the required effective permittivity. Design, manufacturing, and characterization steps are discussed for the specific case of spheres. With such a canonical shape, the effective permittivity can be directly retrieved by comparing far-field electromagnetic scattering measurements with Mie computations. Bistatic RCS measurements and simulations are provided and discussed. They enable us to assess the validity of the proposed methodology, in particular the good adequacy between the adequately chosen unstructured air/material distribution, the desired relative permittivity, and the good homogenization of the object.

Exponential time differencing based efficient SC-PML for RCS simulation

To efficiently simulate and calculate the radar cross section (RCS) related electromagnetic problems by employing the finite-difference time-domain (FDTD) algorithm, an efficient stretched coordinate perfectly matched layer (ESC-PML) based upon the exponential time differencing (ETD) method is proposed. The proposed implementation can not only reduce the number of auxiliary variables in the SC-PML regions but also maintain the ability of the original SC-PML in terms of the absorbing performance. Compared with the other existed algorithms, the ETD-FDTD method shows the least memory consumption resulting in the computational efficiency. The effectiveness and efficiency of the proposed ESC-PML scheme is verified through the RCS relevant problems including the perfect E conductor (PEC) sphere model and the patch antenna model. The results indicate that the proposed scheme has the advantages of the ETD-FDTD method and ESC-PML scheme in terms of high computational efficiency and considerable computational accuracy.