Radar Cross Section Simulation Research Articles

Multi‐frequency analysis of Gaussian process modelling for aperiodic RCS responses of a parameterised aircraft model

Radar cross-section (RCS) of an object is a complex function of various geometric variables, frequency and angles of incidence. In this work, an artificial intelligence solution is provided to predict the non-deterministic characteristics of RCS using the supervised machine learning algorithm that involves Gaussian process (GP) regression. A parametrised aircraft model is used to generate training data where five variables are selected as predictors while the response is chosen to be monostatic RCS in the azimuth plane. To provide a comparison of GP modelling-based predictions, shooting and bouncing rays-based multi-frequency RCS simulations are used and the results show good agreement. To further validate the GP-based modelling approach, the data of a design point is compared with the measured RCS of 1:8 scaled-down aircraft model, which confirms the accuracy of the proposed methodology. Good prediction capabilities of GP regression for RCS evaluation of complex geometries and requirement of small data set make it an excellent tool for exploring the large design space as well as integration into multi-disciplinary design optimisation environments.

Preparation of cobalt sulfide nanoparticles wrapped into reduced graphene oxide with tunable microwave absorption performance

Great improvements for wireless techniques and electronic devices require effective electromagnetic (EM) absorbing materials to solve EM radiation and interference problems. Herein, cobalt sulfide/reduced graphene oxide (CoS/rGO) nanocomposites were prepared through a simple one-pot hydrothermal method. The microwave absorption performance of CoS/rGO nanocomposites with different rGO proportions was systematically investigated. The CoS/rGO 1:1 nanocomposite achieves the reflection loss (RL) value of −37.3 dB at 8.6 GHz. The effective RL values (<−10 dB) of the CoS/rGO 1:1 nanocomposite are obtained in the frequency of 3.4–18 GHz while the thickness varies from 2.0 mm to 5.0 mm. Additionally, the simulated radar cross section results indicate that the CoS/rGO nanocomposites can efficiently suppress the strong EM scattering of metal plate in different incident degrees. These achievements demonstrate that the CoS/rGO nanocomposites can be used as high-performance microwave absorbing materials.

Periodic Three-Dimensional Nitrogen-Doped Mesoporous Carbon Spheres Embedded with Co/Co3O4 Nanoparticles toward Microwave Absorption.

Although various bio-inspired materials with outstanding mechanical, acoustic, and optic properties have been developed, bio-inspired materials for microwave absorption applications are rarely reported. Herein, under the inspiration of the opal structure, for the first time, a kind of Co@Co3O4/nitrogen-doped (N-doped) mesoporous carbon sphere (Co@Co3O4/NMCS) with a periodic three-dimensional structure toward microwave absorption application was designed and synthesized. The microwave absorption performance was optimized with respect to the content of Co@Co3O4 nanoparticles. Co@Co3O4/NMCS with ∼20 wt % Co@Co3O4 achieves a reflection loss of -53.8 dB at 5.7 GHz. The simulated radar cross section demonstrated that the Co@Co3O4/NMCS can efficiently suppress the strong electromagnetic scattering from a metal groove structure, which further reveals its excellent absorbing performance. These periodic porous structures of N-doped mesoporous carbon spheres combined with the magnetic Co@Co3O4 nanoparticles contribute to the excellent microwave-absorbing performance.

An UWB Physical Optics Approach for Fresnel-Zone RCS Measurements on a Complex Target at Non-Normal Incidence.

In this paper, we propose a fast method for measuring the radar cross section of a complex target at non-normal incidences and Fresnel region antenna-to-target distances. The proposed method relies both on the physical optics approach and on averaging the field distribution over the transmitting and receiving antenna apertures. The ratio between the analytical expression of the radar cross section at far-field and Fresnel region results in a field-zone extrapolation factor. The RCS resulting from the scattering parameters measured at Fresnel region distances is then corrected with that field-zone extrapolation factor. The method is suitable to be used in a perturbed, multipath environment by applying the distance averaging technique, coupling subtraction or time gating. Our technique requires a very simple measuring configuration consisting of two horn antennas and a vector network analyzer. The experimental validation of the proposed technique demonstrates reasonable agreement with simulated radar cross section at non-normal incidence.

Researches on the scattering characteristics in THz band of conductor cylinder coated with parabolic distribution and time-varying plasma media

It is widely acknowledged that inhomogeneous and time-varying plasma can effectively reduce the back scattering radar cross section (RCS) and THz wave has the potential to penetrate the plasma and against the plasma stealth. Therefore, the backscattering and bistatic radar cross section (RCS) of conductor cylinder coated with parabolic distribution and time-varying plasma media in THz wave band are studied by the Runge-Kutta Exponential Time Differencing-Finite Difference Time Domain (RKETD-FDTD) method in this paper. The influences of plasma parameters are analyzed. From both the backscattering and bistatic RCS simulations, it is obviously that inhomogeneous and time-varying plasma cloaking system makes a significant difference on reducing the RCS and improve the plasma stealth while electromagnetic wave in THz region can successfully weaken its influence and contribute to the anti-stealth.

Fast and accurate RCS evaluation via high‐performance parallel FDTD simulation

In this study, a fast and accurate method to predict the radar cross-section (RCS) of large-scale and complicated shape targets is proposed based on a high-performance parallel finite difference time-domain (FDTD) numerical method. To this end, several most popular parallel computation methods [including OpenMP, graphics processing unit (GPU), and message-passing interface (MPI)] are discussed first. Based on this discussion, a novel MPI–OpenMP–GPU hybrid parallel computation scheme for FDTD is developed. Moreover, the corresponding load-balance parallel configuration is discussed as well. Since this hybrid parallel scheme combines the merits of existing parallel technologies, the computation performance is remarkably improved. The results show that the computation time of the RCS simulation of a large-scale target can be reduced from 3 days to 0.8 h, that is, ∼98.9% time saving.

Deep CNNs as a method to classify rotating objects based on monostatic RCS

Radar systems emit a time-varying signal and measure the response of a radar-reflecting surface. In the case of narrowband, monostatic radar signal domain, all spatial information is projected into a radar cross-section (RCS) scalar. The authors address the challenging problem of determining shape class using monostatic RCS estimates collected as a time series from a rotating object tumbling with unknown motion parameters under detectability limitations and signal noise. Previous shape classification methods have relied on image-like synthetic aperture radar or multistatic (multiview) radar configurations with known geometry. Convolutional neural networks (CNNs) have revolutionised learning tasks in the computer vision domain by leveraging images and video rich with high-resolution two-dimensional (2D) or 3D spatial information. They show that a feed-forward CNN can be trained to successfully classify object shape using only noisy monostatic RCS signals with unknown motion. They construct datasets containing over 100,000 simulated RCS signals belonging to different shape classes. They introduce deep neural network architectures that produce 2% classification error on testing data. They also introduce a refinement network that transforms simulated signals to appear more realistic and improve training utility. The results are a pioneering step toward the recognition of more complex targets using narrowband, monostatic radar.

Experimental Results and Numerical Simulation of the Target RCS using Gaussian Beam Summation Method

This paper presents a numerical and experimental study of Radar Cross Section (RCS) of radar targets using Gaussian Beam Summation (GBS) method. The purpose GBS method has several advantages over ray method, mainly on the caustic problem. To evaluate the performance of the chosen method, we started the analysis of the RCS using Gaussian Beam Summation (GBS) and Gaussian Beam Launching (GBL), the asymptotic models Physical Optic (PO), Geometrical Theory of Diffraction (GTD) and the rigorous Method of Moment (MoM). Then, we showed the experimental validation of the numerical results using experimental measurements which have been executed in the anechoic chamber of Lab-STICC at ENSTA Bretagne. The numerical and experimental results of the RCS are studied and given as a function of various parameters: polarization type, target size, Gaussian beams number and Gaussian beams width.

Uncertain Feature RCS Analyses based on Wavelet Decomposition

A novel uncertainty analysis approach for radar cross section (RCS) data is proposed in this paper. The wavelet decomposition method is applied to separate the origin data for uncertain feature extraction. Methods of distribution fitting and analysis are studied and data uncertainty distribution characteristics are also compared. Several benchmark cases from RCS simulation are taken to validate the proposed method. The impact of attitude uncertainty on the target RCS is also studied.

On the Influence of Scattering From Traffic Signs in Vehicle-to-X Communications

As an important scatterer in vehicle-to-X (V2X) communication scenarios, traffic signs frequently appear along roads and can affect the propagation channel appreciably. Although traffic signs can be considered as an important part in such scattering scenarios, knowledge of their bistatic radar cross section (RCS) is still absent. This paper presents an integration of the analytical models, full-wave simulation, measurement, and validation of the bistatic RCS of three types of representative traffic signs for V2X communication. First, the total RCS of the traffic signs is calculated by summing up the field contributions of the individual parts with their own phase relationships. Furthermore, simulations using full-wave analysis are performed to validate the analytical models for RCSs in the far field under plane-wave illumination. Since the high-frequency calculation techniques used here are applicable only under plane-wave excitation, the traffic-sign parts are divided into small elements, where this precondition is locally valid. Measurements are conducted in an open-area test site at the National Metrology Institute of Germany to validate the model in the near field (spherical wave from a point source). Corresponding comparisons show that the method of decomposing the traffic sign into small parts supports an effective way to embed the analytical models into ray-tracing tools, thus improving propagation modeling in V2X communication.

The attitude estimation of three-axis stabilized satellites using hybrid particle swarm optimization combined with radar cross section precise prediction

An attitude estimation approach based on the hybrid particle swarm optimization (HPSO) and radar cross section (RCS) precise prediction for the three-axis stabilized satellites in space is presented in this paper. The modified strategies with quantum behavior operator and cloud mutation based on the multi-phase particle swarm optimization are used to increase the diversity of particles, reduce the objective function evaluation times and improve the global searching ability. The simulated RCS sequences of three-axis stabilized satellites at the specified epoch are determined by the method combined the precise orbit and the RCS of satellites calculated by fast multipole method. The mean square error between measured RCS sequences and simulated RCS sequences is considered as the objective function. The attitude estimation problem is transferred to an optimization problem by minimizing the objective function with attitude angles, which is solved by HPSO. The operation procedure is shown clearly, and the set of measurement is analyzed. The numerical results of optimizing the test functions showing better behavior of the proposed algorithm method than standard particle swarm optimization in terms of accuracy are provided. Representative examples validate the accuracy and the anti-noise jamming ability of the proposed algorithm for attitude estimation of three-axis stabilized satellites.

A novel dynamic RCS simulation and analysis method considering attitude perturbation

Radar cross-section (RCS) error between measurement and simulation has been an important issue in target electromagnetic scattering research. Besides the intrinsic limitation of numerical modelling techniques, other factors like environmental noise also contributes to the error. For dynamic targets, the attitude perturbation from complex and unpredictable interferences is the major source of RCS error. This paper proposes a dynamic RCS simulation and analysis method considering attitude perturbation. Random variables with uniform distribution are chosen to model the attitude perturbation. Frequency and perturbation amplitude responses of RCS differences are analyzed. The degree of RCS data consistency is quantitatively presented explicitly using the cumulated probability within error tolerance. The credibility zone provides the reasonable region of dynamic RCS distribution under attitude perturbation. The corresponding expectation value is suitable for the quantitative evaluation of RCS data. Entropy is introduced into the RCS difference uncertainty evaluation for the first time. Experimental results validate the feasibility of the methods and prove that the consideration of attitude perturbation in dynamic RCS simulation is favorable in data credibility enhancement.

Numerical simulation of RCS for carrier electronic warfare airplanes

This paper studies the radar cross section (RCS) of carrier electronic warfare airplanes. Under the typical naval operations section, the mathematical model of the radar wave’s pitch angle incidence range analysis is established. Based on the CATIA software, considering dynamic deflections of duck wing leading edge flaps, flaperons, horizontal tail, and rudder, as well as aircraft with air-to-air missile, anti-radiation missile, electronic jamming pod, and other weapons, the 3D models of carrier electronic warfare airplanes Model A and Model B with weapons were established. Based on the physical optics method and the equivalent electromagnetic flow method, by the use of the RCSAnsys software, the characteristics of carrier electronic warfare airplanes’ RCS under steady and dynamic flights were simulated under the UHF, X, and S radar bands. This paper researches the detection probability of aircraft by radars under the condition of electronic warfare, and completes the mathematical statistical analysis of the simulation results. The results show that: The Model A of carrier electronic warfare airplane is better than Model B on stealth performance and on discover probability by radar detection effectively.

A Method to Determine Shielding Effectiveness in a Reverberation Chamber Using Radar Cross-Section Simulations With a Planar Wave Excitation

A method of determining electromagnetic interference shielding effectiveness of various cases has been developed using a modeling technique where radar cross section (RCS) is used in the calculation of shielding effectiveness and a planar wave is utilized to model mode stirring in the reverberation chamber. In addition, a new shielding effectiveness equation is derived in terms of RCS. Three different test cases based on the small form-factor pluggable family are measured and compared to the simulation results based on the derived shielding effectiveness equation. The measurement and simulation results are plotted and compared to validate the proposed modeling methodology. It was found that results from the measurement and simulation are in good agreement and the simulation method is validated.

Analysis of Radar Cross Section Reduction of Fighter Aircraft by Means of Computer Simulation

This paper presents a preliminary study of the Radar Cross Section (RCS) reduction on the fighter aircraft. First, it was studied the RCS of the aircraft from computational simulations based on prior knowledge of vulnerable areas of this aircraft to radar threats. Subsequently, the possible applications of Radar Absorbing Materials (RAM) on the surface of the aircraft were evaluated, in order to reduce its RCS. The absorber material used in the simulations was denominated FC70, which has good attenuation in the range of 10 to 12 GHz. The study of this reduction was accomplished by applying RAM in four different scenarios at the frequency of 11.1 GHz, where the material is more sensitive. The RCS simulations of the fighter aircraft and its RCS reduction by RAM application were carried out with the support of the software “Computer Simulation Technology” (CST), version 2012. Such technology makes it possible to simulate the application with an absorber material layer on the surface of the aircraft. For the study of the RCS reduction on the fighter aircraft, it was first necessary to develop a detailed 3D model of the fighter aircraft, and it was developed with the software “Computer Aided Three-Dimensional Interactive Application” (CATIA). In conclusion, it is impossible to make much progress attempting to retrofit stealth onto a conventional aircraft because if the shape is wrong, no amount of absorbing material treatments will reduce the RCS.

Design and Implementation of Radar Cross-Section Models on a Virtex-6 FPGA

The simulation of radar cross-section (RCS) models in FPGA is illustrated. The models adopted are the Swerling ones. Radar cross-section (RCS) which is also termed as echo area gives the amount of scattered power from a target towards the radar. This paper elucidates the simulation of RCS to represent the specified targets under different conditions, namely, aspect angle and frequency. This model is used for the performance evaluation of radar. RCS models have been developed for various targets like simple objects to complex objects like aircrafts, missiles, tanks, and so forth. First, the model was developed in MATLAB real time simulation environment and after successful verification, the same was implemented in FPGA. Xilinx ISE software was used for VHDL coding. This simulation model was used for the testing of a radar system. The results were compared with MATLAB simulations and FPGA based timing diagrams and RTL synthesis. The paper illustrates the simulation of various target radar cross-section (RCS) models. These models are simulated in MATLAB and in FPGA, with the aim of implementing them efficiently on a radar system. This method can be generalized to apply to objects of arbitrary geometry for the two configurations of transmitter and receiver in the same as well as different locations.

Dynamic RCS Simulation of a Missile Target Group Based on the High-frequency Asymptotic Method

② (National Electromagnetic Scattering Laboratory, Beijing 100854, China) Abstract: To simulate dynamic Radar Cross Section (RCS) of missile target group, an efficient RCS prediction approach is proposed based on the high-frequency asymptotic theory. The minimal energy trajectory and coordinate transformation is used to get trajectories of the missile, decoys and roll booster, and establish the dynamic scene for the separate procedure of the target group, and the dynamic RCS including specular reflection, edge diffraction and multi-reflection from the target group are obtained by Physical Optics (PO), Equivalent Edge Currents (EEC) and Shooting-and-Bouncing Ray (SBR) methods. Compared with the dynamic RCS result with the common interpolation method, the proposed method is consistent with the common method when the targets in the scene are far away from each other and each target is not sheltered by others in the incident direction. When the target group is densely distributed and the shelter effect can not be neglected, the interpolation method is extremely difficult to realize, whereas the proposed method is successful.

Rough Surface RCS Measurements and Simulations Using the Physical Optics Approximation

The objective of this paper is to develop innovative approaches to obtain analytical expressions of the radar cross section (RCS) of perfectly conducting random rough surfaces under the physical optics (PO) approximation. The led approaches take into account the specific geometrical properties of the considered surfaces to calculate their RCS. The objective is to reduce the computing time with respect to the numerical PO technique, which requires two numerical integrations. All developed approaches are validated by comparison with a commercial code (the multilevel fast multi-pole method (MLFMM) of FEKO), used as a reference, and with measurements performed on three selected rough surfaces samples.

RANGE-LIMITED UAV TRAJECTORY USING TERRAIN MASKING UNDER RADAR DETECTION RISK

Military manned and unmanned aerial vehicles (UAVs) may perform missions in contested airspace, where survival of the vehicle requires avoidance of hostile radar coverage. This research sought to determine optimum flight-path routes that make maximum utilization of UAV terrain-masking opportunities and flight range capability to avoid radar detection. The problem was formulated as one of constrained optimization in three dimensions; advantageous solutions were identified using Algorithm A*. Topographical features were exploited by the algorithm to avoid radar detection. The model included provisions for preferred altitude ranges, adjustable aircraft climb- and descent- rate envelopes, movement costs based on fractional detection probability, radar horizon masking, and simulated radar cross-section lookup tables.

IMPROVEMENT OF ITERATIVE PHYSICAL OPTICS USING PREVIOUS INFORMATION TO GUIDE INITIAL GUESS

We propose an improved method of iterative physical optics (IPO) to analyze electromagnetic scattering by open-ended cavities. The traditional IPO method uses a flxed number of iterations; if this number is too small, the accuracy of the estimated monostatic radar cross section (RCS) of open-ended cavities degrades as the incident angle of the incident fleld increases. The recently- introduced adaptive iterative physical optics-change rate (AIPO-CR) method uses a variable number of iterations; compared to the IPO method, it predicts monostatic RCS more accurately, but requires more computation time. In this paper, a new algorithm is devised to improve both the monostatic RCS prediction accuracy of the IPO method, and the computational e-ciency of the AIPO-CR method. The proposed method, iterative physical optics-retained previous solution (IPO-RPS), calculates the currents at one incident angle, then reuses them as the initial currents of iterations for the next incident angle. In simulations of the monostatic RCS for various open-ended cavities, the IPO-RPS method was more accurate than the traditional IPO method, and computationally more e-cient than both the IPO and AIPO-CR methods.