Evaluation Of Radar Cross Section Research Articles

Partial RCS Evaluation Method for Low-Observable Aircraft Design using PEC and PMC Boundaries

For the design of low-observable aircrafts, more commonly termed stealth, it is necessary to analyze the influence of each airframe part for radar cross section (RCS) reduction. To achieve this aim, a partial RCS evaluation method is developed via the nonstandard finite-difference time-domain (NS-FDTD) technique. The new scheme handles the scattering waves caused by body parts, such as the intake and cockpit of the aircraft, by masking the perfectly electric conductor (PEC) and perfectly magnetic conductor (PMC) boundaries. Compared to the use of the perfectly matched layer (PML), the proposed algorithm is straightforward to apply to the overall RCS evaluation of various aircraft configurations with electrically large size.

Analysis of Calibration-Free Detection Techniques for Frequency-Coded Chipless RFID

In this article, two calibration-free detection techniques including temporal separation detection and dual-polarized interrogation are analyzed for chipless radio frequency identification (RFID), and the design guidelines to improve the detection reliability are proposed. The two techniques aim to obtain electromagnetic signatures without measuring the response of clutter, removing the limitation on the evaluation of radar cross section (RCS), which requires measuring the response of clutter yet is widely used in the literature. However, no research findings are available concerning the detection reliability, design complexity, and computational efforts for the two techniques. This study analyzes these calibration-free detection techniques in terms of online detection and off-line design process. Concerning online detection, the two techniques are implemented in the same frequency band (2.0–4.0 GHz) with data capacity of 8 bits. Sixteen IDs are sampled, and the associated tags are fabricated. Their detection reliability is tested as the function of read range in four environments. Concerning the off-line design process, the sensitivity of design parameters is evaluated for each technique. The performance of the two approaches is compared; furthermore, to improve the robustness in real-world applications, optimum arrangements for filtering, temporal windows, and sampling points are characterized.

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.

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.

Evaluation of Radar Cross Section in Aerial Operations by using POFACETS for a standard Unmanned Aerial Vehicle (UAV)

In military and common applications, radar assumes an exceptionally noteworthy job in exploring the vehicle, recognizing for flying machines, ships and so on. Radar cross section is a measure of a target's ability to reflect radar signals in the direction of the receiver. It is obvious that RCS depends on the shape of the reflecting objects. In this paper, a brief overview of various radars used in surveillance applications and radar cross section (RCS) measurement techniques are presented. The objective of this paper is to illustrate methods for obtaining the Radar Cross Section (RCS) of a typical Unmanned Aerial Vehicle (UAV) for various frequencies in radar bands. UAV technologies have advanced tremendously and are being developed successfully. These features lead UAV to patrol even in civil airspace for civilian applications. These objects operate with small radar cross-section and/or on low altitude which imposes security threat. Keeping this view the RCS of a UAV which are flying in civilian airspace has to be determined drastically for security purposes. Several shapes are considered for the estimation of RCS. The results on the variations of RCS for the above objects as a function of frequency, aspect angle are presented. The POFACETS plays a crucial role and provides the user an easy–to–use GUI that allows the input of all necessary parameters, while preventing erroneous data input and other user errors. In this paper the RCS of sphere, ellipsoid and UAV are determined.

RCS Uncertainty Quantification Using the Feature Selective Validation Method

Uncertainty quantification is an important issue in the field of radar cross section (RCS) research. To quantify the impact of specific uncertainty factor on RCS, a novel approach based on the feature selective validation (FSV) method combined with Monte Carlo (MC) method is proposed in this paper. MC method is applied as the basic framework for uncertainty analysis, and FSV is initially employed to compare the results derived from sufficient uncertainty simulations. To facilitate and enhance the massive data assessment, a novel single and direct indicator of FSV is proposed as a quantitative descriptor of data uncertainty. The feasibility of the proposed method in RCS uncertainty quantification is benchmarked through many RCS evaluation examples. The impact of attitude uncertainty on the target RCS, including the scene of dynamic flight, is also studied by the proposed method.

Electromagnetic scattering characteristics of double S-shape exhaust nozzle with different coating medium parts

As one of the strong electromagnetic scattering source of the aircraft, the radar cross section (RCS) of the nozzle can be reduced by the special geometry and coating microwave absorbing material at the backward direction of the aircraft. In order to simulate the radar scattering characteristics of six coating models and one metal surface model of double S-shape nozzle, the mode combining impedance boundary condition with iterative physical optics (IPO) method is built. Forward and back-forward IPO method and open MP, MPI parallel computing technology are added to accelerate the convergence and reduce computational time. Besides, the ray tracing method is also adopted to improve the efficiency of geometric blanking judgment. The RCS variation regulations of 7 models under X waveband are obtained. The results indicate that coating medium can effectively diminish the RCS of double S-shape exhaust system. Proper coating method can not only reduce the RCS of exhaust system significantly, but also be economical, easy to coat and light-weight. Compared with all parts coating medium model, the model which is only coated at nozzle outlet can reduce microwave absorbing material cost by 73.6% and ensure that the maximal increment of RCS is less than 15.6%. Comparing with the metal model case, The RCS will decrease by at least 18.5%. The improved IPO method can be applied to the RCS evaluation of cavity and the study of coating absorbing material method, and provide technical support for the coating medium model experiment.

Measurement and evaluation of radar cross section for furniture in an indoor propagation channel

Abstract. This paper has attempted to evaluate the radar cross section (RCS) of two furniture items in an indoor environment in a frequency range of 3–7 GHz of the ultra-wideband (UWB) range. The RCS evaluation is achieved through an extended version of the radar equation that incorporates the channel transfer function of scattering. The time-gating method was applied to remove the multipath effect, a phenomenon which typically occurs in the indoor environment. Two double-ridged waveguide horn antennas for both vertical and horizontal polarizations were used to obtain the transfer function of scattering of the furniture prior to analysis in order to derive their bistatic RCS. The RCS results validate the applicability of the proposed extended radar equation to the indoor propagation prediction.

Fabrication of Radar Absorbing Structure and Evaluation of Radar Cross Section: Case Study of Hybrid Shells

Fiber-reinforced composite materials have outstanding mechanical and electrical properties; their applications have been expanded to commercial products as well as military components. Using composite materials, researchers have studied the radar absorbing, or `stealth' technology. In this research, to develop the radar absorbing structure (RAS), hybrid composite materials are fabricated into three-dimensional `C' and `U' shape shells. A series of experiments and analysis is conducted to characterize the RAS shells. The hybrid composite consists of absorbing layers made of a three-phase composite (glass fiber/epoxy/carbon-black 5 wt%), and reflection layers made of carbon fiber reinforced epoxy. To manufacture the spring-back-free composite shells, aluminum molds with additional bending angles are used during the cure process of composite. Finally, to evaluate the radar absorbing efficiency of the RAS, radar cross section (RCS) is measured by a compact range method. The hybrid RAS shows an average radar absorption efficiency of 11 dB.

Parallelisation issues for high speed time domain integral equation analysis

Computation of scattering from multi-wavelength bodies presents large computational requirements. Here is discussed the parallelisation strategy required for effective exploitation of a novel fast algorithm for integral equation time domain (IETD) analyses. The development and examples are couched in terms of electromagnetic scattering and radar cross section evaluation.

Radar cross section of arbitrarily shaped bodies of revolution

The radar cross section (RCS) of an arbitrarily shaped, homogeneous dielectric body of revolution (BOR) is evaluated by the surface integral equation (SIE) formulation and the method of moments. Method accuracy is verified by the good agreement with the exact solutions for the RCS of a dielectric sphere. To demonstrate the advantages of this method, the RCS for a complex BOR model of human torso is computed with a nonaxially incident plane wave. Seven Fourier modes are considered in the computation. The SIE and approximate integral equation (AIE) formulations are next given for the RCS evaluation of a composite dielectric and conducting BOR. For the cases considered, both formulations give the same surface currents and RCS results. However, significant savings in computer storage and CPU time are realized for the AIE approach, since only one current (electric or magnetic) need be determined for RCS evaluation. >