Radar Detection Technology Research Articles

Compatible metasurface for ultra-wideband radar and switchable infrared stealth

In response to the rapid advancements in radar detection technology and the widespread deployment of infrared sensors, single-function stealth materials are increasingly challenged to meet the sophisticated demands of concealment within complex electromagnetic environments. As a result, there is a pressing need for research into metamaterial structures that can simultaneously deliver ultra-wideband radar stealth and controllable infrared invisibility. Here, a novel metamaterial structure was proposed and realized, comprising vertically integrated infrared stealth and radar stealth layers, with the aim of accomplishing both ultra-wideband radar stealth and controlled infrared invisibility. Coded units were designed based on the geometric phase modulation mechanism and then arrayed through a random matrix strategy optimized by a genetic algorithm, yielding a radar stealth layer characterized by outstanding properties such as ultra-wideband radar stealth and insensitivity to polarization states. A temperature-adaptive infrared stealth switching function was successfully achieved by incorporating vanadium dioxide, a phase-change material, into the infrared stealth layer, exploiting its insulator-to-metal phase transition at a critical temperature. The fabrication and performance testing of the samples have further validated the practicality and rationality of the design scheme. This work can not only open up innovative pathways for the advancement of multi-band compatible stealth technology but is also of great significance for the application of electromagnetic shielding and stealth technologies in complex settings.

Structure Design And Optimization Approach For Low RCS Screws

With the rapid development of radar stealth and detection technology, large numbers of screws and rivets have become a major factor that affecting the aircraft’s invisibility. This is because these components have a significant impact on the overall radar cross section of the aircraft, when the electromagnetic scattering characteristic of strong scattering sources is greatly reduced. By analyzing the scattering contribution of the head and body to the screw, it has been obtained that the geometric structure of the head plays a primary role in influencing the overall radar cross section of the screw. According to the scattering mechanism and stealth principle, a shape design method for the low RCS screw is proposed, and then we investigated the scattering characteristic of the octagonal, hexadecagonal, and circular head screws respectively. Furthermore, a structure optimization approach for low RCS screws is introduced which takes the angle of the incident wave into account. This has resulted in the development of a corresponding triangular screw with low detection capabilities. The simulation results show that within the operating frequency band of radar, the triangular head screw has a maximum RCS reduction of approximately 30.1dB compared to a traditional round head screw in [-90°,90°]. On average, there is a reduction of 12.6dB. The simulated results demonstrate the effectiveness and feasibility of the proposed design and optimization method for low RCS screw structures

State-of-the-art radar technology for remote human fall detection: a systematic review of techniques, trends, and challenges

State-of-the-art radar technology for remote human fall detection: a systematic review of techniques, trends, and challenges

Design of a comprehensive sounding system for observing underdense meteors and ionospheric irregularities

Radar detection technology has been used to observe meteors since the last century. According to the echoes of electromagnetic waves scattered by meteor trails, the drift velocity of meteors is calculated to research the atmospheric dynamics characteristics in their distribution height. In this paper, complementary code sequences are applied to a Very High Frequency (VHF) ionospheric sounding system. Unlike the common VHF meteor radar, the system parameters can be set with a pulse duty cycle, allowing for flexible adjustment of detection range. At the same time, the detection frequency can also be adjusted within a certain range, breaking through the traditional fixed frequency detection mode. Moreover, by employing a miniaturized antenna array composed of an orthogonal dipole antenna for the VHF receiving, the system takes account of the requirements of the inversion algorithms of meteor radar and the detection need for the irregularities sounding concurrently, achieving the function of detecting multiple targets. Therefore, the system is called the Wuhan VHF Comprehensive Sounding (WHCS) system. This system has the function of integrating transmission and reception, which can be directly detected by a single station or synchronously detected through the separation of transmission and reception. This system has the function of internal channel calibration to compensate for the phase error of meteor echoes. Through further analysis of the detection data, the height distribution of meteors, as well as typical echoes of ionospheric irregularities, were obtained. The experiments verified the availability of the system scheme and its engineering application significance.

Design of a broadband multifunctional switchable absorber/reflector based on active frequency selective surfaces

Metamaterial absorbers are candidates for stealth systems due to their excellent wave modulation capabilities. With the rapid development of radar detection technology, the switching ability of metamaterial absorbers is becoming more demanding. A broadband multifunctional switchable absorber/reflector based on active frequency selective surfaces (AFSS) is presented in this paper. The proposed structure comprises an absorbing layer, a switching layer, and a ground with air spacers sandwiched between each layer. The PIN diodes can realize significant broadband conditioning performance between absorption and reflection functions by switching four operating states: ‘00’, ‘01’, ‘10’, and ‘11’. The bias network of this structure features horizontal and vertical configurations that independently coordinate the two polarization directions. It is worth noting that the bias network of the designed structure is very simple to minimize the impact on the structure. Distributions of surface current, an equivalent circuit model, and structural parameters are analyzed for a better professional insight into the working mechanism of the absorber/reflector. Finally, a prototype is fabricated and measured to verify the simulation.

Research on Coal Mine Geological Exploration Based on Borehole Geological Radar

Drilling geological radar has the advantages of high resolution, large detection depth, and high flexibility in the field of underground exploration, which can provide accurate and reliable data support for geological engineering, mineral resource development, and other fields. Based on the advancements in borehole geological radar detection technology, the borehole geological radar has been successfully introduced into a coal mine in Guizhou, and the actual on-site detection application is carried out. The research results show that the roadway and the evasion chamber can be clearly seen in the detection results of the 1901 aircraft transport alley, and there is an area of obvious signal anomaly in the 1808 return lane boring surface detection section. Drilling radar is applied to coal mine underground, the detection results have strong accuracy and reference, and the promotion and application of coal mine underground have broad prospects.

Broadband radar absorbing metamaterial based on Al @SiO2 conductive composite film.

Artificially designed metamaterial structures can manipulate electromagnetic waves, endowing them with exotic physical properties that are not found in natural materials, such as negative refractive index, superlens, and inverse Doppler effect. These characteristics are widely applied in various engineering and military applications. Due to increasingly complex application environments and innovation in radar detection technology, the combination of broadband absorption performance under thin thickness and efficient preparation methods at low cost is often the focus of research on new generation stealth materials. Here, we propose Al@SiO2 composite conductive film metamaterial (Al@SiO2 CCFM) to achieve wideband absorption of electromagnetic waves. This metamaterial structure combines two resonant units, resulting in three absorption bands in the absorption curve. The results show that the absorption rate of the metamaterial is above 90% in the frequency range of 10.6 GHz to 26.0 GHz. The resonance mechanism between multiple structures is a prerequisite for achieving wideband absorption. The materials Al and SiO2 used in Al@SiO2 CCFM are inexpensive and abundant, and the fabrication method is simple. Therefore, they hold great potential for large-scale applications in the multispectral stealth and electromagnetic shielding field.

Research on the Technique of Determining the Internal Structure of Ancient Stone Pagodas Based on the Discriminant Features of Ground Penetrating Radar

Abstract Obtaining detailed information about the design and construction of ancient stone pagodas is challenging due to their significant age. Due to this, the internal structure is still unknown, and the analysis of their structural safety lacks a solid foundation. The purpose of this paper is to research ancient stone pagodas and propose adequate methods for identifying their internal structure and assessing their damage status using ground-penetrating radar nondestructive detection technology. The internal structure of the pagoda is inferred through a comprehensive process of layer-by-layer scanning using shielded antennas of varying frequencies, incorporating distance correction. The results demonstrate that by selecting suitable radar antenna frequencies, both test profiles become visible, and the position and characteristics of the internal substantial reflection area exhibit a high degree of consistency, mutually reinforcing each other. The White Pagoda in Hangzhou is believed to have both a mortise and tenon joint structure and a column structure. The ground penetrating radar detection method proves to be effective and has valuable applications.

Roman stone masonry walls: The application of Ground Penetrating Radar to ancient structures

An investigation on estimating Roman stone masonry wall thickness using non-invasive Ground Penetrating Radar (GPR) and Light Detection and Ranging (LiDAR) technology is presented in this paper. Historical building conservation and structural evaluation require correct wall thickness measurements. The methodology encapsulates data collection, signal processing, and interpretation techniques, including the use of local frequency attributes tailored for historical masonry structures. The main perimeter wall at the Circus of Maxentius, Rome, Italy, is used as the case study. The results indicate that GPR is capable of accurately estimating the thickness of Roman stone masonry walls. By conducting a comparative analysis against a wall section with a known thickness, it has been demonstrated that GPR is a dependable and precise method for conducting archaeological and architectural research. This study highlights the potential of using GPR attributes as a non-destructive investigative methodology in the field of heritage preservation. Future research includes extracting and improving further attributes and applying this approach to other historical structures.

Super-resolution Localization Problem Based on the Mobile Scenario

Target positioning has always been a hot research topic in the field of sensors. In recent years, radar detection technology has become increasingly mature, resulting in a large number of radar sensors have begun to be used in traffic, security, medical and other fields for target detection. This paper mainly studies the super-resolution localization problem of FMCW FMCW in moving scenes. It analyzes the echo data by mathematical modeling to obtain the distance and angle information of the object to find the place of the object. To restore the motion trajectory of objects more realistically and achieve super-resolution positioning, a super-resolution radar positioning model based on Kriging interpolation based on the Fourier spectrum is established. By constructing a frame of intermediate frequency data Fourier spectrum tensor space, Fourier spectrum analysis is used to obtain the spectral characteristics of spatiotemporal changes when objects move. The Fourier spectrum surface is reasonably predicted through the statistical method - kriging interpolation. More Fourier spectrum information of objects in the time dimension can be obtained, and then more object points can be restored to achieve super-resolution positioning. This is widely used in the automotive field, which develops autonomous driving systems to help drivers better control the vehicle and reduce the probability of car accidents.

Breakthrough and Practice of Ground Penetrating Radar Detection Technology in Baiyangdian Lake

In order to investigate the stratum structure of the lake bottom in the Baiyangdian Lake area, implement the test of the water-based ground penetrating radar detection system, explore the working mode of the water-based radar detection, compare the water exploration capabilities of different hardware devices, analyze the electromagnetic wave propagation characteristics in the Baiyangdian Lake area, and interpret the geophysical response of the native strata at the bottom of the lake. The stratum structure data in the 15m depth range of the bottom of the lake was obtained to provide a basis for the establishment of a three-dimensional geological model of the Dian District. This technical achievement can strongly promote the construction of a lake and wetland water-land integrated technical method system.

Application Research of 3D Geological Radar Detection Technology in Urban Road Disease Survey

With the comprehensive detection and risk assessment industry of urban road underground diseases taking shape and the long-term development of new technologies, new methods and new equipment, this paper introduces the important breakthrough of 3D geological radar detection technology. Such nondestructive testing site acquisition can achieve high-density seamless detection, qualitative accuracy of data interpretation, accurate determination of road disease scope, detection data has long-term preservation and application research value.

Study on Impact of Various Void Conditions on Shallow Rectangular Masonry-Concrete Power Tunnel and Surrounding Roads

To solve the problem of a potential void near a shallow rectangular masonry-concrete power tunnel, the ground-penetrating radar (GPR) detection technology is used and multiple GPR detection lines are placed to detect concealed void. The GPR images of circular and square voids are obtained, which can help increase accuracy of void identification. The models that cover 9 circular voids and 9 square voids are created to investigate how various forms and positions of void will affect the internal forces of the power tunnel structure and surrounding roads. In terms of morphological characteristics, according to the research results, the impact of a circular void on tunnel and surrounding roads is slightly stronger than that of a square void. If the circular void and square void are at 135° and 115°, respectively, the maximum shear force of the tunnel structure occurs at the floor. If both circular and square voids are at 115°, the maximum axial force of tunnel structure occurs at the right side wall. If both circular and square voids are at 135°, the maximum bending moment of tunnel structure occurs at the floor. If both circular and square voids are at 155°, the ground settlement and pavement stress of surrounding roads are maximized. Generally, if a void occurs at the middle or lower part of the side wall or near the side of the floor in a shallow rectangular masonry-concrete power tunnel, its adverse impact is at its worst. Therefore, GPR detection of the voids at the lower and middle parts and the side of the floor in the power tunnel should be intensified, in order to eliminate the risk of a void near power tunnel.

Thermal stability of Ni3ZnC0.7: As tunable additive for biomass-derived carbon sheet composites with efficient microwave absorption

With the rapidly development of radar detection technology and the increasingly complex application environment in military field and electromagnetic pollution surrounded by electron devices, increasingly demand is needed for electromagnetic wave absorbent materials with high absorption efficiency and thermal stability. Herein, a novel Ni3ZnC0.7/Ni loaded puffed-rice derived carbon (RNZC) composites are successfully prepared by vacuum filtration of metal-organic frameworks gel precursor together with layered porous-structure carbon and followed by calcination. The Ni3ZnC0.7 particles uniformly decorate on the surface and pores of puffed-rice derived carbon. The puffed-rice derived carbon@Ni3ZnC0.7/Ni-400 mg (RNZC-4) sample displayed the best electromagnetic wave absorption (EMA) performances among the samples with different Ni3ZnC0.7 loading. The minimum reflection loss (RLmin) of the RNZC-4 composite reaches −39.9 dB at 8.6 GHz, while widest effective absorption bandwidth (EAB) of RNZC-4 for RL < −10 dB can reach 9.9 GHz (8.1–18 GHz, 1.49 mm). High porosity and large specific surface area promote the multiple reflection-absorption effect of the incident electromagnetic waves. The Ni3ZnC0.7 nanoparticles provide a large number of interfaces and dipole factors. Analysis reveals that the RNZC-4 remained general stability under 400 °C with formation of a small amount of NiO and ZnO phases. Surprisingly, at such high temperature, the absorbing properties of the material are improved rather than decreased. Obviously, the material still maintains good electromagnetic wave performance at high temperature, and implies that the absorber shows good performance stability. Therefore, our preparations exhibit potential applications under extreme conditions and a new insight for the design and application of bimetallic carbides.

Radar Cross-section of a target and attenuation of electromagnetic waves in sandstorms

The sand particles suspended in the atmosphere can cause the attenuation of electromagnetic waves (EWs) and affect the electromagnetic scattering properties of a target during sandstorms. In this study, a theoretical analysis is offered for the prediction of the EWs attenuation and the radar cross section (RCS) of a target in sandstorms. In the model, an equivalent medium approximation is performed by considering the non-uniform charge distribution on the sand particles, and the effect of the charged sand particles on the scattering characteristics of a target is also taken into account. Numerical results show that the RCS of a target is severely affected in sandstorms. Besides, the charged sand particles have a much greater effect on the target's RCS than the case of the uncharged sand particles. It can be found that the average variation value of the target's RCS decreases nearly exponentially with the increase of visibility, and increases nearly linearly with the distance between the target and incident wave source. Finally, an empirical formula is presented to calculate the RCS of an arbitrarily shaped metal target in a homogeneous lossy medium. These investigations will be of significant benefit to radar detection technology in sandstorms.

Multimode‐Assisted Broadband Impedance‐Gradient Thin Metamaterial Absorber

Metamaterials have become a promising alternative for stealth technology due to their impressive abilities to freely manipulate electromagnetic waves. With the development of radar detection technology, stringent performances are required for metamaterial absorbers (MAs), such as wideband, wide‐angle operation, and thin thickness. Herein, a systematic strategy to achieve thin broadband MAs based on trilayer indium tin oxide (ITO) resistive films with multimodes is proposed. The operation mechanism and bandwidth enhancement are analyzed and discussed in terms of the equivalent circuit model and surface current distributions. Guided by the established impedance‐gradient theory, an absorber with high‐efficiency absorption is achieved. Numerical results show that it achieves operation bandwidth (reflection loss &lt;−10 dB) ranging from 6.8 to 20.8 GHz and a fractional bandwidth of 101.4%. To demonstrate the applicability, a proof‐of‐concept sample is fabricated with a total thickness of only 3.5 mm, that is, 0.079 λ L at the lowest operating frequency. A good agreement of results between simulation and experiment has validated the effectiveness of our strategy, indicating broadband and large‐angle operation. It is believed that the research will stimulate the realization of wide‐angle broadband absorbers with thin thickness and further improve the application of stealth technology relying on absorption.

Reasearch on scattering characteristics of THz waves from a parabolic plasma-coated 2D metallic cylinder

Terahertz wave detection technology is regarded as an important research direction for solving plasma stealth. In this paper, we mainly study the penetration ability of terahertz waves into the plasma to apply terahertz waves in anti-stealth technology. We are going to build a two-dimensional metallic cylinder of unmagnetized plasma coverage, using Runge–Kutta Exponential Time Differencing-Finite Difference Time Domain method to calculate radar scattering cross-section. The effect of the plasma thickness, collision frequency and other parameters on the scattering characteristics is discussed, the numerical results indicate that terahertz wave has a strong penetration ability for plasma, which can be used to improve radar detection technology to deal with plasma stealth technology.

Application of Nondestructive Testing Technology in Quality Evaluation of Plain Concrete and RC Structures in Bridge Engineering: A Review

The development and application of nondestructive testing technology for prestressed reinforced concrete structures in the field of infrastructure construction were summarized in this study via the analysis of relevant literature worldwide. The detection methods, detection principles, and detection instruments in quality evaluation of prestressed reinforced concrete structures were analyzed and compared, based on which, acoustic emission detection technology, impact echo detection technology, ultrasonic detection technology, infrared thermography detection technology, ground-penetrating radar detection technology, piezoelectric transducer detection technology, and X-ray detection technology were summarized. Additionally, the advantages, disadvantages, and application scope of each detection method were focused upon and analyzed comparatively. It is indicated that further improvement in the detection visualization, accuracy, and efficiency for most nondestructive testing technologies is available by optimizing the algorithm and combining artificial intelligence technology with neural network deep learning, precise positioning, and imaging analysis of the quality defects in prestressed reinforced concrete structures. The results of this study can provide technical reference for the further application and research of nondestructive testing technologies in the quality inspection of prestressed reinforced concrete structures.

Analysis of abnormal heating of 66kV dry-type air-core reactor grounding device

When dry-type air-core reactors are in operation, the surrounding grounding devices, fences and other closed structural parts are abnormally hot. Because there is no effective analysis and detection methods for concealed projects such as grounding devices, it brings great difficulties to on-site analysis of problems; this article is based on the site conditions Theoretical analysis and the use of ground penetrating radar detection technology to study a 66kV dry-type reactor grounding device abnormal heating problem, through the analysis of the detection results, it is found that the reason for the heating of the dry anti-grounding device is that the grounding device has a circulating current in the alternating field; The design and construction of grounding devices of dry-type air-core reactors in new projects will provide certain reference significance.

Review of the Evolution of Phased-Array Radar

Ever since the human race discovered how bats locate, it has never stopped exploring the use of various waves to analyse and determine the position of objects to be detected. This paper describes the development of radar detection technology since World War II by investigating and analyzing the development of equipment technology in various countries’ militaries, and analyzing the bottlenecks of existing technology, pointing out the possible future direction of development. This paper concludes that the most likely breakthrough direction for the new phased array radar is a breakthrough in materials science (SiCGaN) technology, which will enable the phased array module to be fully digitalised.