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Essay / Radar Absorbing Structural Composite Based on Classified Carbon Materials for X-Band Stealth Applications and the fabrication of a multi-layer carbon Radar Absorbing Structural Composite (RAS) based materials working for X-band applications. The RAS laminates were fabricated using the lossy carbon materials in the epoxy matrix as well as the fabrics glass as supporting elements. Say no to plagiarism. Get a tailor-made essay on “Why Violent Video Games Should Not Be Banned”? Get the original essay Initially, various RAS laminates were fabricated using vacuum bagging technique and characterized for their permittivity and loss tangent values. Furthermore, based on the electromagnetic design and optimization, the graded laminates were stacked for an optimized final configuration of the RAS composites. The developed RAS was characterized for its electromagnetic properties using the free space measurement system and exhibits a minimum reflection loss of 10 dB in the X-band frequency region. The fabricated composite exhibits remarkable mechanical properties and shows its potential application for stealth radar applications.IntroductionStealth technology, which includes radar cross section (RCS) reduction, has become essential in the era of electronic warfare. Reducing RCS can be achieved through aircraft shaping, using radar absorbing material (RAM) coatings and radar absorbing structures (RAS). Aircraft shaping includes designing external features of the aircraft to reduce the reflection of electromagnetic (EM) waves in the RADAR direction. RAM and RAS are developed with the aim of absorbing electromagnetic radiation and thus minimizing reflected waves. Airplane shape has its own limitations as it can interfere with the external profiles defined by aircraft designers to meet aerodynamic requirements. Therefore, the developments of RAM and RAS have become essential for the reduction of RCS. RAMs are typically manufactured in the form of sheets consisting of an insulating polymer as the matrix material and lossy magnetic or dielectric filler materials. RAMs are easily applied to the surfaces of existing structures but they increase structural weight and have poor mechanical and environmental resistance properties. . Thus, RAMs are not stand-alone materials and cannot be used as load-bearing structures. Additionally, they require constant maintenance and repairs. RAS consists of fiber-reinforced composites and lossy materials that are dispersed within the matrix of the composites. The radar absorption efficiency of RAS is achieved from materials that offer special absorption properties and structural features such as the stacking sequence of composite layers. The stacking characteristics of composites facilitate multilayer structures, which are necessary to broaden the reflection loss bandwidth. For a lossy load to be very effective, it must have high conductivity for wave attenuation, a high aspect ratio to form a conductive network, and a small size relative to the depth of the skin. The absorption and reflection characteristics of an RAS depend on a number of variables, including frequency, incident angle andpolarization of the EM wave, as well as the permittivity, permeability and thickness of each layer of the RAS. In this study, the RAS for the X-band frequency region was designed and developed using porous carbon black and carbon fibers as radar absorbing materials and glass/carbon fabric as reinforcement in the epoxy backing. The RAS was developed by stacking the four different layers using a vacuum bag molding technique and characterized for their mechanical and electromagnetic properties in the X-band frequency region by a free space measurement system . The layer stacking sequence for this RAS was obtained by carrying out simulation studies using the layer properties, i.e. effective permittivity and thickness. To determine the effective permittivity of an individual layer, it was manufactured separately and evaluated using the free space measurement system. Fabrication of Flush Laminates The matrix system used to manufacture the composites was Araldite 5052 (epoxy resin) and Aradur 5052 (hardener) from Huntsman. Advanced Materials Pvt Ltd. It is a cold curing epoxy system with low viscosity (1000 – 1500 mPaS for Araldite 5052 and 40 – 60 mPaS for Aradur 5052 at 250 °C) and long pot life (2 hours per 100 ml at room temperature). the epoxy/hardener ratio was 100:38 parts by weight. A 300 g/m² E-glass 8H satin weave fabric was selected as reinforcement. First, the four individual RAS layers were fabricated by varying the filler concentration in a defined order (Table 1). Since the filler materials used in this study are conductive, their proportion in the resin system and the stacking sequence of these layers are very critical for the fabrication of an effective RAS. First, the absorbent fillers were mixed with a matrix system until a uniform dispersion of each filler material was achieved. Then, the modified matrix material was applied to the reinforcing plies by wet lamination method. Finally, the individual RAS layers were fabricated by vacuum casting technique. TABLE I Weight % of radar absorbing fillers compared to composite layers RAS layers Carbon fiber (wt % in epoxy) Carbon black (% by weight in epoxy) S4 x yS3 2x 2yS2 3.5x 4yS1 5x 6 yearsElectromagnetic characterization of flush laminatesThe Free Space Measuring System (FSMS) from HVS Technologies, Pennsylvania, USA, as well as the PNA E8364B vector network analyzer from Agilent Technologies, USA, were used to measure the complex permittivity and reflection loss of the RAS stacks and final RAS. composites in the X-band frequency region. The FSMS consists of a pair of point-focused horn lens antennas to provide plane-wave illumination focused on the sample measurement plane. The FSMS was calibrated using the Thru-Reflect-Line (TRL) calibration technique with time domain gating. The variation of dielectric constant and loss tangent of composite stacks with frequency in the X-band frequency region can be clearly observed from the graph as the permittivity values keep increasing in increasing order from stack1 to stack4. Stack “4” has the highest true permittivity value (14.82-12.32) and it has a higher concentration of lossy ingredients, resulting in a loss tangent value varying from 3.20- 3.15, while the RAS “1” stack has the lowest value of real permittivity (4.94-4.99) and loss tangent value varying from 0.04 to 0.01. Electromagnetic design of ras composites. A.
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