Journal articles: 'Radar Absorbing Materials (RAM)'

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Ramya, K. "Radar Absorbing Material (RAM)." Applied Mechanics and Materials 390 (August 2013): 450–53. http://dx.doi.org/10.4028/www.scientific.net/amm.390.450.

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This paper briefly outlines the research and development activities in radar absorbing materials. Military defense scientists to the possibility of using coating materials to render aircraft or other military vehicles less visible to radar and, preferably, to control such visibility. The highly conducting surface of a metal vehicle is an excellent reflector of radar, but an absorbing layer would suppress the radar signal at the receiver station. Radar absorbing material currently in military and commercial use are typically composed of high concentrations of iron powders in a polymer matrix. These materials are both very heavy and very costly, two key limitations to their adoption for many applications. The performance of these coatings, particularly those using spherical particles, is dependent upon how closely the spheres are packed together. Thus the most efficient coating would be one approaching the density of solid iron with a minimum amount of resin included to electrically insulate the particles from one another. That is, the attenuation efficiency increases faster than the weight, so that a thinner coating with the same attenuation, can be used, providing an overall weight savings. Unfortunately, the particles, when produced, are of non-uniform diameter and not necessarily uniformly round. A window member composed of a transparent resin or inorganic glass with a transparent conducting film such as gold or ITO coated, is used as an electromagnetic wave shield window for stealth aircraft. However, the transparent conducting film, especially ceramic transparent conducting film such as ITO does not deform sufficiently to follow the deformation of the window material. Therefore the transparent conducting film might crack even with relatively little deformation, which can occur during an actual flight.

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Lagarkov, Andrey Nikolayevich, Vladimir Nikolayevich Kisel, and Vladimir Nikolayevich Semenenko. "Radar Absorbing Materials Based on Metamaterials." Advances in Science and Technology 75 (October 2010): 215–23. http://dx.doi.org/10.4028/www.scientific.net/ast.75.215.

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The use of metamaterial for design of radar absorbing material (RAM) is discussed. The typical features of the frequency dependencies of , , ,  of composites manufactured of different types of resonant inclusions are given as an example. The RAM characteristics obtained by the use of the composites are given. It is shown that it is possible to use for RAM design the metamaterials with both the positive values of ,  and negative ones. Making use of the frequency band with negative  and  it is possible to create a RAM with low reflection coefficient in a wide range of the angles of electromagnetic wave incidence.

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Y. Al Jubory, Ammar. "Microwave Absorbing Characteristics Study of Three Layers Radar Absorbing Materials (RAM)." Rafidain Journal of Science 20, no. 2 (March 1, 2009): 160–72. http://dx.doi.org/10.33899/rjs.2009.40230.

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Aytaç, Ayhan, Hüseyin İpek, Kadir Aztekin, and Burak Çanakçı. "A review of the radar absorber material and structures." Scientific Journal of the Military University of Land Forces 198, no. 4 (December 15, 2020): 931–46. http://dx.doi.org/10.5604/01.3001.0014.6064.

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The development of technologies that can rival the devices used by other countries in the defense industry, and more importantly, can disable their devices is becoming more critical. Radar absorber materials (RAM) make the detection of the material on the radar difficult because of absorbing a part of the electromagnetic wave sent by the radar. Considering that radar is one of the most important technologies used in the defense industry, the production of non-radar materials is vital for all countries in the world. Covering a gun platform with radar absorber material reduces the radar-cross-sectional area (RCA) value representing the visibility of that platform on the radar. This review aims to present the electromagnetic principles and developed Radar Absorbent Materials (RAM) during decades from the 1960s. The frequency range 8-12 GHz in the electromagnetic spectrum is named the microwave region and used in airport radar applications. Revised basis of electromagnetic theory and defined by a variety of absorbent materials and some design classification types and techniques are described in this article.

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Krishna, K. Murali, Amit Jain, Hardeep Singh Kang, Mithra Venkatesan, Anurag Shrivastava, and Sitesh Kumar Singh. "Development of the Broadband Multilayer Absorption Materials with Genetic Algorithm up to 8 GHz Frequency." Security and Communication Networks 2022 (February 17, 2022): 1–12. http://dx.doi.org/10.1155/2022/4400412.

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A widely used genetic algorithm (GA) is endorsed to improve the design of a multilayer microwave radar absorbing material (MMRAM) which shows good absorption of radar waves over a broad frequency range. In this research, the authors have used genetic algorithm based on MMRAM which plays an important role in defense and civil applications. The scope of multilayer microwave radar absorbing material (MMRAM) is that it can absorb radar signals and reduce or eliminate their reflection. Its primary use is in defense and certain commercial enterprises. The multilayer RAM design demands the superiority of suitable materials to be used in different layers, a decision about multiple layers, and the optimum breadth of an individual layer. The permeability and permittivity of the materials varying with frequency in a fictitious material are used. The effect of change in thickness and the number of layers of RAM on reflectivity is studied. Since the material characteristics are frequency-dependent, different restrained conditions are used for frequency bands to identify the RAM that has good electromagnetic absorption in the frequency range of 1 to 8 GHz.

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Teber, Ahmet, Ibrahim Unver, Huseyin Kavas, Bekir Aktas, and Rajeev Bansal. "Knitted radar absorbing materials (RAM) based on nickel–cobalt magnetic materials." Journal of Magnetism and Magnetic Materials 406 (May 2016): 228–32. http://dx.doi.org/10.1016/j.jmmm.2015.12.056.

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Chen, Xin, Xiang Xuan Liu, Xuan Jun Wang, and Yuan Liu. "Optimized Design for Multi-Layer Absorbing Materials Based on Genetic Algorithm." Advanced Materials Research 681 (April 2013): 324–28. http://dx.doi.org/10.4028/www.scientific.net/amr.681.324.

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In order to synthesize the multi-layer radar absorbing materials (RAM) with a thin thickness and wide bandwidth, accelerating genetic algorithm (GA) with constraints and elitist strategy is employed to design the multi-layer RAM satisfied by a special value of reflection loss to electromagnetic wave. Given predefined available materials with frequency-dependent permittivity and permeability, the GA technique determines the optimal material choice for each layer and its thickness. The algorithm was successfully applied to the synthesis of double-layer to four-layers RAM coatings in the frequency range of 2-18GHz,and the optimization results was evaluated.

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Muratov, D. G., L. V. Kozhitov, A. V. Popkova, E. Yu Korovin, E. V. Yakushko, and M. R. Bakirov. "Study of the radar absorption of metal-carbon nanocomposites (review)." Industrial laboratory. Diagnostics of materials 89, no. 1 (January 21, 2023): 35–45. http://dx.doi.org/10.26896/1028-6861-2023-89-1-35-45.

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Development of the technology for the synthesis of magnetic nanoparticles of metals and alloys has opened up the possibility of their use in the field of radar-absorbing materials (RAM). The results of studying the properties of nanocomposites, method for the synthesis of metal-carbon nanocomposites by pyrolysis using infrared heating are reviewed. The magnetic, electromagnetic, and radar-absorbing properties of the obtained nanocomposites depending on the synthesis temperature and metal concentration were studied. It is shown that the chosen metals, alloys (FeCo) and carbon material are effective for isolating magnetic nanoparticles when developing hybrid radar-absorbing composites. Moreover, methods for controlling the radar-absorbing properties of hybrid composites and the prospects for improving the impedance matching are considered. An analysis of the efficiency of absorption of electromagnetic radiation by FeCo/C nanocomposites synthesized by different methods is presented. The possibility of controlling the morphology and properties of metal-carbon nanocomposites using certain approaches to synthesis, varying the compositions of precursors, and the orientation of FeCo nanoparticles synthesized in the form of flakes in the composite has been revealed. The results of the study can be used to improve the technique of using FeCo/C nanocomposites obtained by pyrolysis of organometallic precursors based on polyacrylonitrile in the field of radar-absorbing materials.

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Zainuri, Mochamad, and Dina Andryani. "Characterization of BaM and PaNi-Based Radar Absorbency (RAM) Behavior with Multilayer Geometry Structure for X-Band Absorption." Materials Science Forum 966 (August 2019): 54–59. http://dx.doi.org/10.4028/www.scientific.net/msf.966.54.

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Behavioral characterization of radar absorbent material consisting of Polyaniline (PaNi) and Barium M-Hexaferrite (BaM) has been successfully synthesized by solid state method. Polyaniline conductive material was synthesized using the polymerization method with DBSA dopant. A Radar Absorbing Materials (RAM) is characterized by X-Ray Fluorescence (XRF), X-Ray Diffraction (XRD), Fourier Transform Infrared (FTIR), Four Point Probe (FPP), Scanning Electron Microscope (SEM) and Vector Network Analyzer (VNA). The ion Zn 2+ is dopping into the BAM structure, where Zn 2+ ions replace Fe2+ ions in Hexaferrite barium so that the phase becomes soft magnetic materials . RAM and PANi particles are combined with ship paint to form radar wave absorbent coatings. The layer is coated with multilayer geometry on AH 36 type A steel, with thicknesses of 2.4 mm, 3.6 mm, 4.8 mm and 6 mm respectively. The X-band wave absorption was identified by VNA testing, where the maximum reflection loss value was found at 6mm thickness with a reflection loss value - 32.6 dB at 8.4 GHz frequency. Reflection loss values of multilayer variations with a thickness of 2.4 mm, 3.6mm and 4.8mm each have reflection loss values of -8.02 dB, -19.13 dB and -28.9 dB respectively in the x band frequency range.

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Sivakoti, Kavya Kumari, Mamatha Basava, Rao Venkata Balaga, and Balarama Murty Sannidhi. "Design Optimization of Radar Absorbing Materials Using Particle Swarm Optimization." International Journal of Applied Metaheuristic Computing 8, no. 4 (October 2017): 113–32. http://dx.doi.org/10.4018/ijamc.2017100107.

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Microwave absorbers have numerous applications in the modern-day military and civil industries. This paper presents the performance of the Particle Swarm Optimization (PSO) algorithm to obtain optimal designs for multilayer microwave absorber over different frequency ranges. The goal of this optimization is to make decision about number of layers, selection of suitable combination of materials from a predefined database, thereby minimizing the overall reflection coefficient and designing a low weight electromagnetic absorber, which absorbs the maximum amount of incident electromagnetic energy. Microwave absorbers or radar absorbing materials (RAM) performance is studied by varying thickness and number of layers. For each different configuration obtained with PSO, simulated results are presented. The best results obtained using PSO are compared with those obtained using another optimization technique, genetic algorithm and also compared with the results computed using standard RCS computation software.

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Zainuri, Mochamad, Triwikantoro, and Dimas Ayu Primadani. "Absorption Electromagnetic Waves in X-Band Range Using Barium M-Hexaferrite Dopping Zn Ions and Polyaniline Conductive with Variation of Thickness Coating." Key Engineering Materials 860 (August 2020): 260–66. http://dx.doi.org/10.4028/www.scientific.net/kem.860.260.

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Since the discovery of hexagonal ferrite or known as hexaferrites, research into the development of these materials related to commercial fields and technology has been very rapid. The use of hexaferite as a magnetic material that can be mass produced has a wide application field. Therefore, the magnetic properties of hexaferrites should be adjusted to meet these applications requirements. In this respect, cation substitution is one of the most effective ways to obtain a suitable material. Double layer coating design with variations in thickness of 1 mm, 2 mm, 3 mm, and 4 mm on Radar Absorbent Material (RAM), with Barium M-Hexaferrite (BaM) BaFe12-xZn xO19 as magnetic material with variations in doping concentration of Zn2+ ions x = 0, 0.3 and 0.9 have been successfully synthesized by the solid state reaction method. Likewise with Polyaniline (PANi) with Dodecylbenzene Sulfonic Acid (DBSA) dopant as a conductive material, it have been successfully synthesized by the polymerization method. Radar absorbing materials (RAM) are characterized using X-Ray Diffraction (XRD), Four Point Probes (FPP), Fourier Transform Infrared (FTIR), Vector Network Analyzer (VNA), and Scanning Electron Microscope (SEM). The results of XRD characterization showed that the largest primary phase was obtained at BaM x= 0.9 which was 96.56%. The increassing of concentration dopping of Zn2+ ions to influence of decreasing the magnetic dipole of magnetic materials and the magnetic properties be come softmagnet materials. The variations in thickness coating radar absorbing materials the influence of absorption of electromagnetic waves occurs optimally, and the increase of thickness coating have coused the value of loss of reflection and widening of the absorption band of the X-Band range (8-12 GHz) increasing. The highest reflection loss and widening of the absorption band value is obtained from coating BaM x = 0.9 with a thickness of 4 mm, which are respectively - 16.29 dB, and 3.78 GHz. So that it can be concluded that the addition of the doping concentration of Zn2+ ions and the dimensions of the layer thickness can increase the absorption ability of RAM material.

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Thomas, Paulbert, Libimol V. Abdulhakim, Neeraj K. Pushkaran, and Aanandan C. Karuvandi. "Wideband Radar Absorbing Structure Using Polyaniline-Graphene Nanocomposite." C 6, no. 4 (November 5, 2020): 72. http://dx.doi.org/10.3390/c6040072.

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A wideband non-resonant absorber is proposed, and its radar cross section (RCS) reduction is investigated. A discussion on the functional materials available is followed by the design of an absorber on a Plexiglas substrate with polyaniline-graphene nanocomposite as layered square inclusions with thicknesses and conductivities scaled to golden ratio. The measured dielectric properties of polyaniline-graphene nanocomposites are used in the fullwave simulation. The design parameters have been identified and optimized using CST Microwave Studio. As designed structure is fabricated and the reflection is measured. The objective of the work is to demonstrate the use of non-metallic conducting polymer composites devoid of metals for radar absorbing material (RAM) structural designs. The structure is an all-polymer and electrically thin design with a potential to be 3D printed to suit the target object.

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Ayan, Muhammet Çağrı, Serap Kiriş, Ahmet Yapici, Muharrem Karaaslan, Oğuzhan Akgöl, Olcay Altıntaş, and Emin Ünal. "Investigation of cotton fabric composites as a natural radar-absorbing material." Aircraft Engineering and Aerospace Technology 92, no. 8 (July 16, 2020): 1275–80. http://dx.doi.org/10.1108/aeat-01-2020-0018.

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Purpose The purpose of this paper is to investigate cotton fabric behavior that is exposed to radar waves between selected operation frequencies as an alternative radar-absorbing material (RAM) response. Cotton fabric biocomposite materials were compared with carbon fabric composite materials, which are good absorbers, in terms of mechanical and electromagnetic (EM) properties for that purpose. Design/methodology/approach The laminated composite plates were manufactured by using a vacuum infusion process. The EM tests were experimentally performed with a vector network analyzer to measure reflection, transmission and absorption ability of cotton fabric, carbon fabric and cotton–carbon fabric (side by side) composite plates between 3 and 18 GHz. The tensile and low-velocity impact tests were carried out to compare the mechanical properties of cotton fabric and carbon fabric composite plates. A scanning electron microscope was used for viewing the topographical features of fracture surfaces. Findings The cotton fabric composite plate exhibits low mechanical values, but it gives higher EM wave absorption values than the carbon fabric composite plate in certain frequency ranges. Comparing the EM absorption properties of the combination of cotton and carbon composites with those of the carbon composite alone, it appears that the cotton–carbon combination can be considered as a better absorber than the carbon composite in a frequency range from 12 to 18 GHz at Ku band. Originality/value This paper shows how cotton, which is a natural and easily supplied low-cost raw material, can be evaluated as a RAM.

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Richa, Priscila, Roberto Costa Lima, Ana Paula Santiago de Falco, Ana Paula da Silva, Elvia Leal, and Ana Cristina Figueiredo de Melo Costa. "Microwave Absorbing Properties of NiZnCu Ferrite and Polychloropren Composites." Journal of Aerospace Technology and Management, no. 1 (January 21, 2020): 27–32. http://dx.doi.org/10.5028/jatm.etmq.85.

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Radar-absorbing materials (RAMs) have been used in military applications for several decades to reduce radar detection of vessels and aircrafts. In the present work, the performance of Ni0.35Zn0.35Cu0.3Fe2O4 ferrite as a RAM is investigated. The ferrite was firstly synthesized by combustion reaction and then calcinated at 1200 °C for 1 h. Composites were prepared with 80:20, 70:30 and 60:40 concentrations in weight of ferrite:polychloroprene. The X-ray diffraction (XRD) analysis showed a single phase ferrite formation and the scanning electron microscopy (SEM) analysis of the composites showed a good dispersion of the ferrite in the polychloroprene matrix. The electromagnetic (EM) characterization of the composites revealed that the EM attenuation is mainly attributed to magnetic losses observed in the material. The 80:20 composite achieved the best performance and presented a reflectivity of -26.7 dB at 10.2 GHz.

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Yang, Zhaoning, Lu Gao, Wei Ren, Ruiduan Zhang, Yangyang Chen, Qian Zhou, Kai Sun, Ziqi Jie, and Yanmin Jia. "Study on Electromagnetic Performance of La0.5Sr0.5CoO3/Al2O3 Ceramic with Metal Periodic Structure at X-Band." Materials 15, no. 22 (November 17, 2022): 8147. http://dx.doi.org/10.3390/ma15228147.

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A radar absorbing material (RAM) is designed by combining the La0.5Sr0.5CoO3/Al2O3 ceramic and the metal periodic structure. The phase constitution and the microscopic morphology of the La0.5Sr0.5CoO3/Al2O3 ceramic are examined, respectively. The electrical properties and magnetic properties of the La0.5Sr0.5CoO3/Al2O3 ceramic are also measured at the temperature range of 25~500 °C. Based on the experimental and simulation results, the changes in the reflection loss along with the structure parameters of RAM are analyzed at 500 °C. The analytical results show that the absorption property of the RAM increases with the increase in the temperature. When the thickness of the La0.5Sr0.5CoO3/Al2O3 ceramic is 1.5 mm, a reflection loss <−10 dB can be obtained in the frequency range from approximately 8.2 to 16 GHz. More than 90% microwave energy can be consumed in the RAM, which may be applied in the high temperature environment.

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Anuradha, Sathyamurthy, and Jyothi Balakrishnan. "RESONANCE BASED DISCRIMINATION OF STEALTH TARGETS COATED WITH RADAR ABSORBING MATERIAL (RAM)." Progress In Electromagnetics Research M 99 (2021): 69–79. http://dx.doi.org/10.2528/pierm20101001.

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Hardiawan, Haeder Sazli, Lalu Saefullah, and Vito Hanif Addinuri. "Otomotif Kendaraan Tempur POTENSI DARI STRUKTUR DAN MORFOLOGI NANOKOMPOSIT Fe3O4 DOPING Mn DAN rGO SEBAGAI COATING ANTI RADAR." Jurnal Otoranpur 3, Mei (May 31, 2022): 8–18. http://dx.doi.org/10.54317/oto.v3imei.238.

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Penelitian Radar Absorbing Materials (RAM) dalam beberapa tahun terakhir pada bidang militer dilakukan secara intensif. Pemilihan material pembuatan RAM memiliki peran sangat penting untuk menghasilkan kinerja yang baik. Tujuan penelitian ini adalah mengetahui pengaruh komposisi Mn terhadap sturktur kristal, morfologi komposit nano Fe3O4 / rGO Doping Mn, dan potensinya sebagai coating Nanokomposit Fe3O4 / rGO Doping Mn berhasil disintesis dengan metode kopresipitasi. Sampel dikarakterisasi XRD, FTIR dan SEM-EDX untuk mengetahui struktur dan fase, morfologi dari nanokomposit setelah dilakukan doping. Hasil karakterisasi XRD menunjukkan memiliki struktur kristal berbentuk kubik dengan ukuran kristal 11.5 nm dan tidak adanya puncak baru, yang mengidintefikasikan Mn berhasil disubtitusi ke dalam Fe. Pada hasil SEM terlihat bahwa nanokomposit tersusun dari partikel Fe3O4 dan Mn yang berbentuk bulatan yang teraglomerasi dan bentuk bongkahan untuk r-GO, serta memiliki ukuran butir sekitar 15 - 20 nm.

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Liu, Yuan, Jie Lai, and Yun Liu. "Preparation, Characterization, and Microwave Absorption Properties of Cobalt-Doped SrFe12O19 Nanoparticles." Journal of Nanoelectronics and Optoelectronics 16, no. 6 (June 1, 2021): 998–1004. http://dx.doi.org/10.1166/jno.2021.3042.

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Ferrite is the major absorbing components of conventional radar absorbing materials (RAM). However, conventional RAM made of the single-absorbing components cannot meet the comprehensive requirements of “thin, wide, light, and strong.” To overcome this limitation, a composite compound of cobalt-doped SrFe12O19 nanoparticles is currently exploited to improve absorbing ability. SrFe12−xCoxO19 (x = 0, 0.05, 0.1, 0.15, 0.20, 0.25) composite ferrites were prepared using the sol-gel method. Results show that the powders obtained are pure lead-magnetite ferrite, and the properties of the samples are improved evidently after Co substitution. At room temperature, the samples substituted using Co exhibit typical permanent magnetism. When x = 0.2, the maximum saturation magnetization and coercivity of the powders are 55.8 A·2/kg and 302.4 kA/m, respectively. The real complex permittivity part of SrFe12−xCoxO19 first increases and then decreases with the increase in x and has a maximum value of x = 0.2. The complex imaginary permittivity part fluctuates with the increase in x; it first decreases, then increases, and finally decreases. With the increase in x, the complex permeability real part of the sample does not change much between 2 GHz to 16 GHz but first increases and then decreases in the range of 16-18 GHz. The imaginary part of the complex permeability first increases and then decreases, reaching its maximum at x = 0.2. The attenuation constants and absorbing properties of the samples before and after substitution were analyzed. The matching thickness of strontium ferrite (SrFe12O19) is 5.2 mm, the matching thickness of SrFe11,8Co0.2O19 (x = 0.2) is reduced to 2.4 mm, the minimum reflectivity is −24.7 dB (13.8 GHz), and the microwave absorption bandwidth lower than −10 dB is 4.7 GHz (11.6-16.3 GHz). These results indicate that an appropriate amount of Co substitution could greatly improve the absorbing performance of SrFe12O19. This study provides a simple method for the preparation of Co doped strontium ferrite. The microwave absorbing properties of the composite powders are excellent and have potential engineering application value.

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Nadiyyah, Khoirotun, Dwi Wahyu Hardiyanto, Dwi Irma Aprilia, Rizky Firmansyah, Nurul Amaliya Triyuliana, and M. Zainuri. "ANALYSIS OF ACTIVATED CARBON (PETUNG BAMBOO)/LATEX COMPOSITE AS X-BAND WAVE-ABSORBING MATERIAL." JOURNAL ONLINE OF PHYSICS 8, no. 2 (April 1, 2023): 70–76. http://dx.doi.org/10.22437/jop.v8i2.23851.

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In maintaining the sovereignty of a country, especially in border regions was needed defense tools that had the latest technology, such as stealth technology. Stealth technology was applied to military ships or aircraft so that they could not be detected by Radio Detection and Ranging. Stealth technology in this research was realized by coating the ship's or aircraft's body using RAM (Radar Absorbing Material). RAM could be composed of dielectric materials, such as activated carbon. The activated carbon was synthesized from Dendrocalamus Asper. This research aimed to analyze the proper of composition the composite and thickness of the RAM for the X-band wave range. The methods were carbonization, activation by KOH and HCl solutions, and characterization. The characterizations were by XRD, FTIR, and SEM to identify the active carbon phase, and VNA to determine the value of reflection loss. The variations in this research were composite composition (7:3, 9:1) and thickness (1mm, 3mm). And obtained that it has been formed a composite of activated carbon of petung bamboo and latex of rubber tree, which is indicated by the formation of two broad peaks in the diffraction pattern, the presence of band groups C=C, C-C, C-H, C-O, O-H, and morphology with a porous structure. In addition, the highest reflection loss is obtained for the 9:1 composite and thickness of 3 mm, which reached -17.25 dB at a frequency of 9.32 GHz.

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Kailas K. Sawant, Bhavana Shanmughan, K. Balasubramanian, and A.A. Bazil Raj. "Data Analysis of Polyethylene Base RAM for Small Vehicle’s low Signature’s Applications." international journal of engineering technology and management sciences 7, no. 4 (2023): 90–109. http://dx.doi.org/10.46647/ijetms.2023.v07i04.017.

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The signature of radar target is an important aspect in military war. The demands for low signature targets have been increased to achieve the ‘critical mission successes’ in defence. Worldwide scientists and engineers are incessant working on it. This paper presents the data analysis of radar absorbing material (RAM) suitable for attaining of low signature applications for small air vehicles such as sUAV, μUAV, drones, hexcopter, spy birds etc. In this paper, the polyethylene (PE) and their composites characteristics and data analysis are presented, for applications in small air vehicles to attain the lower value of their target signatures. This is achieved in terms of EM measurement parameters of RAM material such as reflection loss, transmission loss, absorption loss, shielding effectiveness (SE), radar cross section (RCS) etc. The obtained values of reflection loss are – 29.49 dB, - 36.91 dB and – 23.94 dB; then, the transmission loss are – 133.18 dB, - 128.70 dB and – 0.19 dB for PE, polyethylene terephthalate (PET) and PET + conductive paint (PETCP) respectively for materials by waveguide measurement (WGM) method. The SE range are – 0.009 dB to – 0.19 dB, - 0.005 dB to - 0.29 dB, and - 0.022 dB to – 1.91 dB in WGM; then, - 9.44E-07 dB to – 1.13E-06 dB, - 9.57E-07 dB to – 1.01 E-06 dB and – 9. 31 E-07 dB to – 1.08E-06 dB in OATS experiments for PE, PET and PETCP respectively for the materials are obtained. The lowest value of RCS in OATS method are 1.63E-08 , 6.46E-08 and 5.63E-08 for PE, PET and PETCP respectively for material are obtained. The contact angle & material thickness (t) are 78.50 & 0.08 mm; 66.18 & 0.09 mm and 93.45 & 0.12 mm for PE, PET and PETCP respectively, are proposed in this paper. There is good agreement between the material controlling parameters design and the tabular analysis presented in this paper. This materials are used as RAM in small aircrafts, sUAV, μUAV, drones, hexcopter, spy birds, ships etc, to attain their low signature value, low RCS, stealth and shielding applications in X – band of 8 to 12 GHz frequency range.

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Zainuri, Mochamad, Rahma Fitri Puspitasari, Deril Ristiani, and Triwikantoro. "The Effects of Layer Thickness of Radar Absorbing Materials Prepared by Double Layer Method on X-Band Wavelength Frequency." Materials Science Forum 966 (August 2019): 35–40. http://dx.doi.org/10.4028/www.scientific.net/msf.966.35.

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Double layer coating with variations in layer thickness on radar absorbent material (RAM), and Polyaniline dobed by DBSA as a dielectric material has been successfully synthesized. As well as Barium M-Hexaferrite doped by Zn2+ at x=0.9 as magnetic material successfully synthesized. Polyaniline has been synthesized by polymerization method and Barium M-Hexaferrite has been synthesized by solid state method. Characterization results obtained the conductivity of Polyaniline and Barium M-Hexaferrite respectively 4.4 × 10-1 S/m and 2.09 × 10-3 S/m, both of which are in range of semiconductor materials conductivity. The presence of Zn2+ doping successfully reduced hard magnetic properties of Barium M-Hexaferrite to be soft magnetic, with coercivity field (Hc) equals 0.0181 Tesla. Based on research that has been done, represent that double layer design with variations PANi : PANi + BaM (3:1) has maximum reflection loss value about -29,6003 dB, and 96.69% of energy absorbed. Whereas in variation of PANi: PANi + BaM (3: 1) has minimum reflection loss value about -15.2937 dB, and 82.21% of energy absorbed. In addition, the coating thickness variations also affect the absorption band width, with the most effective absorption peaks in “D” variation with bandwidth equals 1.81 GHz in range of frequency 8 to 9.81 GHz.

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Kunrath, Kamila, Eduardo Fischer Kerche, Mirabel Cerqueira Rezende, and Sandro Campos Amico. "Mechanical, electrical, and electromagnetic properties of hybrid graphene/glass fiber/epoxy composite." Polymers and Polymer Composites 27, no. 5 (February 12, 2019): 262–67. http://dx.doi.org/10.1177/0967391119828559.

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This study presents the development of a novel three-component composite based on glass fiber/epoxy resin/graphene nanoplatelets (GNPs) aiming to obtain radar absorbing material (RAM). The composite was produced by vacuum-assisted resin transfer molding and characterized under tensile and flexural testing, reflectivity, and electrical conductivity analyses. The mechanical properties were not significantly affected by the incorporation of GNP nanofiller. However, electrical conductivity of the three-component composites increased sharply and the percolation threshold was reached with around 3 wt% GNP (surface conductivity) and 4 wt% GNP (volumetric conductivity). Furthermore, reflectivity showed excellent attenuation (up to 99.99%) in the 8.2–12.4 GHz frequency range. These attenuation levels were obtained even at low concentrations (0.1 wt%) of GNP nanofiller, indicating the possibility of producing composites with low cost and easy processing for advanced applications as RAMs.

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BHATTACHARYYA, AMITAVA, and MANGALA JOSHI. "CO-DEPOSITION OF IRON AND NICKEL ON NANOGRAPHITE FOR MICROWAVE ABSORPTION THROUGH FLUIDIZED BED ELECTROLYSIS." International Journal of Nanoscience 10, no. 04n05 (August 2011): 1125–30. http://dx.doi.org/10.1142/s0219581x11009490.

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Conventional radar absorbent materials (RAM) such as iron ball (carbonyl iron) and carbon black prove less effective against modern homing devices specially those which operate at low frequency microwaves. Hybrid nanoparticles based on ferrite are found to be more suitable for such applications. Iron (Fe) coated carbon nanoparticles can also be successfully used for conducting, sensing and electromagnetic shielding or radar absorbent applications. Among the carbon nanoparticles, nanographite has its potential for such applications because of its conductivity, nanomagnetism and layered structure. Therefore, nanographite coated with Fe , nickel (Ni) or chromium is an attractive choice for microwave absorbing material. In the present study, Fe coating has been carried out on acid functionalized nanographite by a simple and novel fluidized bed electroplating process. The acid functionalization helps to adhere the coating on the nanographite surface. The electroplating of Fe–Ni alloys is recognized as an anomalous co-deposition and is characterized by a preferential deposition of the less noble metal Fe , even when the concentration of Ni in the bath was higher than that of Fe . The efficiency of the electrolytic coating of powdered material is strongly affected by the applied current density, the rotation speed, the average size of the particles and the density of the electrolyte-powder suspension. The nanoparticles were further dispersed in polyurethane matrix and cast into nanocomposite films. The microwave absorption property observed in the frequency range 300 MHz to 1.5 GHz shows that a very thin coating of Fe–Ni helps to absorb the microwave quite efficiently. Fe–Ni coated functionalized nanographite synthesized by this method is thus an effective microwave absorbent material and can find potential use in several defence applications as specialty coatings for fighter aircrafts/radomes and other coated textiles used for aerial surveillance etc.

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Rubeziene, Vitalija, Julija Baltusnikaite-Guzaitiene, Ausra Abraitiene, Audrone Sankauskaite, Paulius Ragulis, Gilda Santos, and Juana Pimenta. "Development and Investigation of PEDOT:PSS Composition Coated Fabrics Intended for Microwave Shielding and Absorption." Polymers 13, no. 8 (April 7, 2021): 1191. http://dx.doi.org/10.3390/polym13081191.

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This study presents the investigation of the electromagnetic properties and resistance performance of electrically conductive fabrics coated with composition containing the conjugated polymer system poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate (PEDOT:PSS). The developed fabrics were intended for electromagnetic radiation (EMR) shielding in microwave range and for absorbing microwaves in radar operating range, so as to act as radar absorbing materials (RAM). The measurements of reflection and transmission of the developed fabrics were performed in a frequency range of 2–18 GHz, which covers the defined frequencies relevant to the application. Four types of fabrics with different fiber composition (polyamide; polyamide/cotton; wool and para-aramid/viscose) were selected and coated with conductive paste using screen printing method. It was found that EMR shielding effectiveness (SE) as well as absorption properties depend not only the amount of conductive paste topped on the fabric, but also resides in the construction parameters of fabrics. Depending on such fabric structural parameters as density, mass per unit area, type of weave, a layer of shield (or coating) just sticks on the fabric surface or penetrates into fabric, changing the shield thickness and herewith turning SE results. Meanwhile, the fiber composition of fabrics influences mostly bonding between fibers and polymer coating. To improve the resistance performance of the developed samples, a conventional textile surface modification technique, atmospheric plasma treatment, was applied. Initially, before plasma treatment and after treatment the fabrics were evaluated regarding an aqueous liquid repellency test, measuring the contact angles for the water solvent. The influence of plasma treatment on resistance performance of coated fabrics was evaluated by subjecting the plasma treated samples and untreated samples to abrasion in the Martindale abrasion apparatus and to multiplex washing cycles. These investigations revealed that applied plasma treatment visibly improved abrasion resistance as a result of better adhesion of the coating. However, washing resistance increased not so considerably.

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Kurniawan, Affandi Faisal, Mohammad Syaiful Anwar, Khoirotun Nadiyyah, Yana Taryana, Muhammad Mahyiddin Ramli, Mashuri Mashuri, Triwikantoro Triwikantoro, and Darminto Darminto. "Preparation and Thickness Optimization of Graphenic-Based Carbon Material as a Microwave Absorber." Trends in Sciences 19, no. 1 (January 1, 2022): 1714. http://dx.doi.org/10.48048/tis.2022.1714.

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The purpose of this study is to optimize the thickness of a layered graphenic-based carbon compound, which is a non-magnetic material derived from biomass (old coconut shell). After the sample was exfoliated using HCl solution, the morphological structure showed that the material used in this study is a reduced graphene oxide (rGO), similar to carbon but with a thickness of less than 10 nm and lateral size in submicron (100 nm). The sample with a 2 mm thickness was then characterized using a vector network analyzer (VNA) to measure its reflection loss (RL). The measurement result is evaluated by converting the S-parameter values (S11 and S21) from the VNA using the Nicolsson Ross Weir (NRW) method to obtain input variables such as relative complex permeability and relative complex permittivity. Following this, the single-layer thickness of the sample was optimized using a genetic algorithm (GA), which can predict the appropriate thickness so that the optimum RL can be obtained. The optimum thickness of the sample was found to be 3.48 mm, which resulted in a much higher RL. The RL was re-measured for verification using a sample with the corresponding optimized thickness, revealing that this optimization is feasibly operational for a radar absorbing material (RAM) design. HIGHLIGHTS Carbon compounds containing graphenic phase derived from coconut shell are functional materials having various unique properties such as superior electrical conductivity, large surface area, and excellent structural flexibility, and microwave absorbtion The single-layer microwave absorber employing carbon compounds has been prepared The layer thickness optimized using a genetic algorithm (GA) can estimate the appropriate design with the maximum reflection loss (RL)

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Pinto, Simone de Souza, and Mirabel Cerqueira Rezende. "Electromagnetic, Morphological, and Electrical Characterization of POMA/Carbon Nanotubes-Based Composites." Journal of Nanomaterials 2017 (2017): 1–9. http://dx.doi.org/10.1155/2017/1989785.

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This study involves the preparation of conducting composites based on poly(o-methoxyaniline) (POMA) and carbon nanotubes (CNT) and the evaluation of them as radar absorbing materials (RAM), in the frequency range of 8.2–12.4 GHz (X-band). The composites were obtained by synthesis in situ of POMA in the presence of CNT (0.1 and 0.5 wt% in relation to the o-methoxyaniline monomer). The resulting samples—POMA/CNT-0.1 wt% and POMA/CNT-0.5 wt%—were incorporated in an epoxy resin matrix in the proportion of 1 and 10 wt%. FT-IR analyses show that the POMA was successfully synthesized on the CNT surface. SEM analyses show that the synthesized POMA recovered all CNT surface. Electrical conductivity measurements show that the CNT contributed to increase the conductivity of POMA/CNT composites (1.5–6.7 S·cm−1) in relation to the neat POMA (5.4 × 10−1 S·cm−1). The electromagnetic characterization involved the measurements of complex parameters of electrical permittivity (ε) and magnetic permeability (µ), using a waveguide in the X-band. From these experimental data reflection loss (RL) simulations were performed for specimens with different thicknesses. The complex parameters show that the CNT in the composites increased ε and µ. These results are attributed to the CNT network formation into the composites. Simulated RL curves of neat POMA and POMA/CNT in epoxy resin show the preponderant influence of POMA on all RL curves. This behavior is attributed to the efficient CNT recovering by POMA. RL results show that the composite based on 10 wt% of POMA/CNT-0.5 wt% in epoxy resin (9 mm thickness) presents the best RL results (≈87% of attenuation at 12.4 GHz).

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Tyagi, Sachin, Ramesh Chandra Agarwala, and Vijaya Agarwala. "Microwave Absorption and Magnetic Studies of Strontium Hexaferrites Nanoparticles Synthesized by Modified Flux Method." Journal of Nano Research 10 (April 2010): 19–27. http://dx.doi.org/10.4028/www.scientific.net/jnanor.10.19.

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M-type strontium hexaferrite nanocrystals of radar absorbing material (NRAM) i.e. SrFe12O19 were synthesized by modified flux method that combine the controlled chemical co-precipitation process for nucleation and complete uniform growth during annealing with NaCl flux. Uniform structural morphological transformation of nanocrystals from needle to hexagonal prism faces were noticed after annealing with increasing of heat treatment (HT) temperature from 800 to 1200°C for 4h. X-ray diffraction (XRD) results show the formation of various phases with increase in annealing temperature. The crystallinity and crystallite size are found to increase with increase in heat treatment temperature (15-40nm). The superparamagnetic behavior of strontium hexaferrite is confirmed by vibrating sample magnetometer (VSM) wherein it was noticed that magnetic field (10000 gauss max) did not have any effect on these materials. The transformation of magnetic properties i.e. from superparamagnetic to ferromagnetic behaviour after heating at various HT temperatures have been revealed by hysteresis loops under VSM study. The increase in saturation magnetization from 2.44 to 75.03 emu/gm is observed. Formation of ultrafine particles has been confirmed through field emission scanning electron microscope (FESEM). About 5 to10% of the needle like crystals in the ‘as synthesized’ condition were transformed to hexagonal pyramidal structure and most of the crystals are found to have plate like hexagonal structures with increase in heat treatment temperatures. The effect of such systematic morphological transformation of nanocrystals was observed in reflection loss properties in X band (8-12 GHz). The maximum reflection loss of -20.05, -24.31, -24.16, -25.22, -25.12, -24.01 dB at 8.1, 8.6, 9.2, 9.6, 10.7, and 12 GHz respectively are observed for the material heat treated at 1200°C. A significant increment from - 6.5 to -25.22 dB at 9.6 GHz in reflection loss (RL) is noticed due to symmetric morphological growth of RAM nanocrystal during annealing.

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Chambers, B. "Radar Absorbing Materials From Theory to Design Characterization K.J. Vinoy and R.M. Jha Kluwer Academic Publishers, PO Box 322, 3300 AH Dordrecht, The Netherlands. 1995. 190pp. Illustrated. £85.25." Aeronautical Journal 101, no. 1003 (March 1997): 141. http://dx.doi.org/10.1017/s0001924000066665.

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Sun, Liang Kui, Hai Feng Cheng, Yong Jiang Zhou, and Wang Jun. "Design and Preparation of Light-Weight Radar Absorbing Material Based on Resistive Frequency Selective Surfaces." Advanced Materials Research 335-336 (September 2011): 976–80. http://dx.doi.org/10.4028/www.scientific.net/amr.335-336.976.

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Light-weight radar absorbing material (RAM) based on resistive frequency selective surfaces (FSS) was designed and prepared. The principle of the resonances of the RAM was analyzed by calculating the impedance of the FSS and the grounded substrate according to the equivalent circuit method, and the results show that a wideband absorbing structure can be gained by producing two adjacent resonances. After design and optimization by Genetic Algorithm (GA), the RAM with absorbing bandwidth of 7.5~18GHz below -10dB was obtained, whose thickness is only 3mm. The designed RAM was gained by preparing resistive patches on the grounded dielectric substrate of rigid polyurethane foam using screen painting technology. The density of the absorber is only 0.2g/cm3, the reflectivity was measured and it shows that the experimental result is consistent with the design one.

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30

Li, Zhengqi. "Ultra-wideband Vivaldi Antenna Loaded with Multi-layer Radar Absorbing Material." Journal of Physics: Conference Series 2405, no. 1 (December 1, 2022): 012009. http://dx.doi.org/10.1088/1742-6596/2405/1/012009.

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Abstract In this paper, the radiation and scattering characteristics of a broadband miniaturized Vivaldi antenna are simulated. The proposed antenna operates at 3.6GHz-15.6GHz. Through calculation, the multi-layer absorbing material with the best broadband absorption loss is obtained, and the RCS reduction is effectively realized by loading RAM on the antenna metal floor. The simulated results between the reference antenna and the antenna loaded with RAM show that the RCS reduction of more than 10 dB under the incident angle of nearly ±70° in the xoz plane is realized, while the radiation performance of the antenna with RAM is well preserved, which proves the significance of absorbing material loading for antenna RCS reduction.

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31

Fisli, A., D. S. Winatapura, E. Sukirman, S. Mustofa, W. A. Adi, and Y. Taryana. "Iron oxide/titania composites for radar absorbing material (RAM) applications." Cerâmica 65, no. 375 (September 2019): 470–76. http://dx.doi.org/10.1590/0366-69132019653752728.

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Abstract Iron oxide/titania composites were synthesized by precipitation method. Amount of iron oxide was varied in the composites. The single phase (anatase) was obtained for the weight ratio of 0-20% and three phases (anatase, magnetite and hematite) were found for the weight ratio of 30% and 40% of iron oxide. The crystallite size of titania decreased with increasing of iron oxide content. The specific surface area, total pore volume and BJH pore volume of the sample increased with increasing iron oxide content in the composite. The composites possessed mesoporous characteristic (6.5-9.6 nm in pore diameter) and exhibited ferromagnetic properties. The measurement of the microwave absorption showed that the 40Fe/Ti composite had the best reflection loss of -14 dB at a frequency of 10.9 GHz. This meant that the electromagnetic wave was absorbed 80% in that frequency. Thus, the developed material can be a promising microwave absorbing agent in radar signature reduction.

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32

Sharma, Rahul, Ramesh Chandra Agarwala, and Vijaya Agarwala. "Development of Radar Absorbing Nano Crystals under Thermal Irradiation." Journal of Nano Research 2 (August 2008): 91–104. http://dx.doi.org/10.4028/www.scientific.net/jnanor.2.91.

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Single phase W-type barium hexaferrite nano crystals of radar absorbing material (RAM) i.e., BaMe2Fe16O27 (Me2+=Fe2+) were synthesized by a modified flux method that combines the controlled chemical co-precipitation process for nucleation and complete uniform growth during in-situ annealing with NaCl flux under vacuum furnace. Uniform structure morphological transformation of nano crystals from spherical to prism faces were noticed after annealing with increasing temperatures from 200 to 1200 oC for 4 h in vacuum. XRD results showed the single phase nanocrystals of BaFe18O27 with increasing crystallanity and size from 10 to 90 nm during annealing. FESEM and TEM were used to investigate the systematic growth processes of various morphologies of nano crystals. The effect of such systematic morphological transformation of nanocrystals was observed in dielectric, dynamic magnetic and refection loss (RL) properties in Kuband (12.4 -18.0 GHz). A significant increment from -15.23 dB to -43.65 dB with wide range of bandwidth in RL loss is noticed due to the symmetric morphological growth of single phase nano crystals of RAM during annealing. This process of crystal growth, morphology evolution and RL enhancement with respect to increasing temperature were also explained in terms of ostwald ripening and quantum size effect.

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Kirillov, V. Yu, P. A. Zhukov, S. Yu Zhuravlev, and M. M. Tomilin. "Radar-Absorbing Materials for Spacecraft." Cosmic Research 58, no. 5 (September 2020): 372–78. http://dx.doi.org/10.1134/s0010952520050068.

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Sun, Hui Min, Zhao Zhan Gu, and Ran Ran Yang. "Study on Absorbing Properties of Honeycomb Absorbing Materials." Advanced Materials Research 815 (October 2013): 645–49. http://dx.doi.org/10.4028/www.scientific.net/amr.815.645.

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Honeycomb absorbing materials were measured using the method of free space in this paper. The reflectance of honeycomb absorbing materials was calculated and simulated, and it was verified based on the measured results. It was demonstrated that this test method was feasible. Through studying on absorbing properties of honeycomb, the results have showed that the radar absorbing properties of honeycomb are related to electromagnetic parameters, as well as thickness of the dip-coatings. With the increase of thickness of the dipping layer, the radar absorbing capability of high frequency and low frequency wave are significantly increased. It is worth noting that the resonance peak moved to the low frequency with the increase of dipping layer thickness. These results are useful for design of honeycomb absorbing materials.

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Wei, Sai Nan, Rui Zhou Li, Li Chen, and Ji Ming Yao. "Research of Fiber Radar Absorbing Materials." Advanced Materials Research 602-604 (December 2012): 835–38. http://dx.doi.org/10.4028/www.scientific.net/amr.602-604.835.

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Electromagnetic parameters and absorbing properties of fiber absorbents (carbon fiber, SiC fiber and polycrystalline iron fiber) were introduced. The influences of the arrangement, thickness and content of the fibers on radar absorbing property were summarized. New development directions of the fiber absorbents were also indicated.

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36

Vinoy, K. J., and R. M. Jha. "Trends in radar absorbing materials technology." Sadhana 20, no. 5 (October 1995): 815–50. http://dx.doi.org/10.1007/bf02744411.

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XIE, Wei, Hai-Feng CHENG, Zeng-Yong CHU, Zhao-Hui CHEN, and Yong-Jiang ZHOU. "Radar Absorbing Properties of Light Radar Absorbing Materials Based on Hollow-porous Carbon Fibers." Journal of Inorganic Materials 24, no. 2 (April 7, 2009): 320–24. http://dx.doi.org/10.3724/sp.j.1077.2009.00320.

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Afanasiev, Anatoly, and Yulia Bakhracheva. "Analysis of the Types of Radar Absorbing Materials." NBI Technologies, no. 2 (October 2019): 35–38. http://dx.doi.org/10.15688/nbit.jvolsu.2019.2.6.

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Bao, Gang, and Jun Lai. "Radar Cross Section Reduction of a Cavity in the Ground Plane." Communications in Computational Physics 15, no. 4 (April 2014): 895–910. http://dx.doi.org/10.4208/cicp.090413.130913s.

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AbstractThis paper investigates the reduction of backscatter radar cross section (RCS) for a rectangular cavity embedded in the ground plane. The bottom of the cavity is coated by a thin, multilayered radar absorbing material (RAM) with possibly different permittivities. The objective is to minimize the backscatter RCS by the incidence of a plane wave over a single or a set of incident angles. By formulating the scattering problem as a Helmholtz equation with artificial boundary condition, the gradient with respect to the material permittivities is determined efficiently by the adjoint state method, which is integrated into a nonlinear optimization scheme. Numerical example shows the RCS may be significantly reduced.

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Fang, Zhi Gang, and Chun Fang. "Novel Radar Absorbing Materials with Broad Absorbing Band: Carbon Foams." Applied Mechanics and Materials 26-28 (June 2010): 246–49. http://dx.doi.org/10.4028/www.scientific.net/amm.26-28.246.

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Carbon foams were prepared by a polymer sponge replication method and their microwave absorbing properties were investigated in this paper. It was found that the electric conductivity of carbon foams increases quickly with the improvement of carbonization temperatures. Moreover, the electric conductivity of carbon foams strongly affects their microwave absorbing performances. As the electric conductivity increases from 0.02 S/m to 1.03 S/m, the dominant electromagnetic behavior of carbon foams changes from transmission to reflection with regard to the incident electromagnetic wave. The best microwave absorbing performance was achieved for the carbon foam with an electric conductivity of 0.46S/m when other parameters are fixed at constants, and absorbing values for the carbon foam exceeds 7dB almost in the whole measured frequency range of 4-15GHz, while the frequencies range for absorbing values exceeding 8dB are about 7 GHz, demonstrating a characteristic of broad absorbing bandwidth. It is to be noted that the absorbing characteristic for the carbon foam with an electric conductivity of 0.46S/m is obtained without any impedance match design, which indicates that carbon foams have the possibility to be applied as broad absorbing bandwidth RAMs.

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Wang, Yanmin, Tingxi Li, Lifen Zhao, Zuwang Hu, and Yijie Gu. "Research Progress on Nanostructured Radar Absorbing Materials." Energy and Power Engineering 03, no. 04 (2011): 580–84. http://dx.doi.org/10.4236/epe.2011.34072.

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42

Liu, YiShan, Xin Huang, PeiPei Guo, XuePin Liao, and Bi Shi. "Skin collagen fiber-based radar absorbing materials." Chinese Science Bulletin 56, no. 2 (January 2011): 202–8. http://dx.doi.org/10.1007/s11434-010-4343-5.

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43

Nam, Young-Woo, Jae-Hwan Shin, Jae-Hun Choi, Hyun-Seok Kwon, Jae-Sung Shin, Won-Jun Lee, and Chun-Gon Kim. "Micro-mechanical failure prediction of radar-absorbing structure dispersed with multi-walled carbon nanotubes considering multi-scale modeling." Journal of Composite Materials 52, no. 12 (September 11, 2017): 1649–60. http://dx.doi.org/10.1177/0021998317729003.

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Conventional radar-absorbing structure is typically manufactured with high weight percentage (wt.%) of carbonaceous nano-conductive particles in the polymer matrix to tailor its microwave absorbing performance. However, these manufacturing methods have some physical limitations with regard to fabrication, due to the high viscosity in the polymer matrix and, inhomogeneous in mechanical and electrical properties. No study has been conducted with micro-mechanical failure prediction of radar-absorbing structure dispersed with multi-walled carbon nanotubes. In order to address these limitations, radar-absorbing structures dispersed with multi-walled carbon nanotubes were designed in the Ku-band (12.4–18 GHz). Additionally, to establish and verify the micro-mechanical failure analysis based on multiscale modeling, finite element analysis was carried out using the Mori–Tanaks mean-field homogenization model within the representative volume element model in the microstructure. In order to verify the Hashin criteria of radar-absorbing structure dispersed with multi-walled carbon nanotube (0.5 wt.%, 1.0 wt.% and 1.5 wt.%), mechanical tests (tensile, compressive and shear test) were conducted according to ASTM standards. In this paper, radar-absorbing structure with irregularly arranged filler and matrix with representative volume element was modeled from the micro-mechanical point of view and the results from Hashin failure criterion were verified both by simulations and experimental results of prediction strengths within the expected error range (lower than 6%). The reliability of application in micro-mechanical prediction of radar-absorbing structure was confirmed considering the multi-scale modeling.

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Zhao, Jun Liang, Li Xin Li, and Zhong Juan Yang. "Dynamic Mechanical Properties of a Novel Structural Radar Absorbing Materials." Applied Mechanics and Materials 364 (August 2013): 771–74. http://dx.doi.org/10.4028/www.scientific.net/amm.364.771.

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A novel structural radar absorbing materials (SRAM), which give the new absorbing microwaves function to the normal resin-base composites, were prepared. The dynamic compressive tests of SRAM were carried out along both in-plane and normal plane directions of composites by means of the Split Hopkinson Pressure Bar (SHPB). In compressive test along in-plane direction, failure happened at the interface between fiber and matrix. Fracture mode and mechanism was proposed to explain these results. The adding of magnetic absorbing particles resulted in the deterioration of the compressive properties. But there was no obvious decrease on compressive strength of SRAM with the radar absorbing properties.

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Sun, Hui Min, Le Chen, and Zhao Zhan Gu. "Characterization and Design of Honeycomb Absorbing Materials." Solid State Phenomena 294 (July 2019): 51–56. http://dx.doi.org/10.4028/www.scientific.net/ssp.294.51.

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Honeycomb absorbing materials are anisotropic structural materials. Depending on the size of honeycomb lattices, the absorbent content of the impregnated layer is different, the thickness of the impregnated layer is different, and the absorbing function of the impregnated honeycomb absorbing materials is also different. For the characterization of electromagnetic parameters of honeycomb absorbing materials, this paper adopts free space method for testing, uses CST software for modeling, and inverts the electromagnetic parameters of honeycomb absorbing structures. The absorbing performance of single-layer and double-layer honeycomb sandwich structures was simulated by RAM Optimizer software. The research shows that the height of the single-layer honeycomb absorbing material is 22mm. When the absorber content is 65%, 75% and 85% respectively, the harmonic peak moves slightly to the low frequency electromagnetic wave with the increase of the absorber content, but the absorbing strength decreases with the increase of the absorber content. For the double-layer honeycomb sandwich structure, the difference of absorber content in the upper and lower honeycomb absorbing materials is smaller, and the absorbing performance is stronger. When the thickness of the wave-transparent panel is thinner, the harmonic peak of the absorbing curve moves slightly to the high frequency.

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46

Shinde, Devika D., V. Babu, and S. V. Khandal. "A Review on Types of Radar Absorbing Materials." Shanlax International Journal of Management 9, S1-Mar (March 19, 2022): 122–27. http://dx.doi.org/10.34293/management.v9is1-mar.4901.

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In this review paper a study about material used for radar absorption is done. Various types of materials possess the property to absorb the radar signals. The properties of material vary based on the composition, additives, manufacturing methods, and other various factors. Different materials such as carbon based, ferrites work well under different frequencies which is discussed in this paper. The absorption of the signals depends on the basic parameters such as permittivity, permeability, reflection loss, the other parameters such as transmission, reflectivity and many more factors.

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Padhy, S., S. Sanyal, R. S. Meena, R. Chatterjee, and A. Bose. "Characterization and performance evaluation of radar absorbing materials." Journal of Electromagnetic Waves and Applications 27, no. 2 (November 12, 2012): 191–204. http://dx.doi.org/10.1080/09205071.2013.743447.

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Taryana, Yana, Azwar Manaf, Nanang Sudrajat, and Yuyu Wahyu. "Electromagnetic Wave Absorbing Materials on Radar Frequency Range." Jurnal Keramik dan Gelas Indonesia 28, no. 1 (June 1, 2019): 1. http://dx.doi.org/10.32537/jkgi.v28i1.5197.

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49

Benderskiy, G. P., Yu M. Molostova, P. A. Rumyantsev, S. V. Serebryannikov, and S. S. Serebryannikov. "Radar-absorbing composite materials based on ferrite powders." Izvestiya vuzov. Poroshkovaya metallurgiya i funktsional’nye pokrytiya, no. 2 (June 16, 2022): 13–21. http://dx.doi.org/10.17073/1997-308x-2022-2-13-21.

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The paper studies the effect of particle sizes of hexagonal ferrite powders on their electrodynamic properties. SrTi0.2Co0.2Fe11.6O19 and BaSc0.2Fe11.8O19 hexaferrites were used as the objects of research. Grinding in a high-energy planetary mill for up to 60 minutes made it possible to obtain hexaferrite powder particles with the average size successively decreasing from 1.5–2 μm to 0.05–0.15 μm. A scanning electron microscope was used for the analysis. Samples were prepared in a mixture with a polymer binder (70% ferrite + 30% polymer), and their electromagnetic radiation (EMR) absorbing capacity was studied in the microwave range from 30 to 50 GHz. It was shown that there is practically no peak corresponding to ferrimagnetic resonance in the composite with ferrite, with a decrease in the average particle size of BaSc0.2Fe11.8O19 hexaferrite powders to 50–150 nm. The dependences of the real and imaginary parts of the magnetic permeability and dielectric constant are given in the frequency range from 107 to 109 Hz. There was no domain wall resonance in the frequency dependence of magnetic losses for a ferrite-based composite mechanically activated for 60 min. SrTi0.2Co0.2Fe11.6O19 ferrite was milled in a bead mill to particles with an average size of 150–300 nm, and then to drying, pressing, sintering at 1360 °С and subsequent grinding to a size of 200–500 μm to obtain similar composites in a bond with a polymer. It was found that the properties of compositions change significantly with a change in the magnetic component synthesis technology: no resonant pattern of EMR absorption was observed. The Curie temperature was measured using the Faraday method. It was shown that it is ~340 °С for the studied material. Therefore, the effect of precursor milling on changes in magnetocrystalline anisotropy was identified.

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Atay, Hüsnügül Yilmaz, and Öykü İçin. "Manufacturing radar-absorbing composite materials by using magnetic Co-doped zinc oxide particles synthesized by Sol-Gel." Journal of Composite Materials 54, no. 26 (May 21, 2020): 4059–66. http://dx.doi.org/10.1177/0021998320927754.

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An indicator of being a strong country in today's world is that they have powerful weapons. In this sector where science is used exceedingly, the “stealth” takes an important place. Radar-absorbing materials are used in stealth technology to disguise an object from radar detection, such that it can allow a plane to be perceived as a bird. In this study, Co-doped zinc oxide reinforced styrofoam sheet composites were manufactured as radar-absorbing materials. For this purpose, Co-doped zinc–ZnO particles were synthesized via the Sol-Gel method with doping concentrations of 0%, 3%, 6%, 9%, and 12%. They were embedded in a styrofoam matrix with different loading levels to see the concentration dependence. The as-prepared powders were characterized by using X-ray diffraction and Scanning Electron Microscope-Energy Dispersive Spectroscopy. Magnetic characterization of samples was carried out using a vibrating sample magnetometer. Finally, the radar-absorbing test was applied with a network analyzer to achieve the main purpose of this research. It was concluded that Co-doped zinc oxide reinforced composites have electromagnetic properties that indicate potential applications in the radar-absorbing area.

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Journal articles on the topic 'Radar Absorbing Materials (RAM)'

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