چكيده به لاتين
Stealth or radar evasion technology has been one of the most important requirements of the military aviation sector to deal with the ever-increasing target detection technologies around the world. Military radars operate in a wide frequency band spectrum that measures the radar cross-section of an aerial structure. The higher the radar cross-sectional area of a structure, the more it can be detected by radar. Therefore, in military applications to provide security, and surveillance, increase survivability, and escape from detection, the radar cross-section of the target should be reduced. The methods of reducing the radar cross-sectional area of an aerial structure can be divided into four main categories: shaping, using radar-absorbing materials, active cancellation, and passive cancellation. Among the above cases, the use of radar absorbent composite coatings due to the ability to manufacture, high strength-to-weight ratio, chemical resistance, low weight, reduction of the desired radar cross-sectional area, absorption bandwidth, and high-frequency absorption peak compared to the method Others are superior. In the current research, radar absorbent composite coatings based on multi-walled carbon nanotubes reinforced with iron carbonyl magnetic particles in the polymer matrix, with different electromagnetic properties in different thicknesses, were made; In the production of these coatings from suitable Nano materials by simultaneously using two types of materials with dielectric and magnetic loss together, both the magnetic and electric components of the radar waves are lost and by adjusting two important parameters Complex Permeability and Complex Permittivity with appropriate values increased the impedance matching between the free space and the absorbent coating surface and prevented reflection. Phase identification was done by X-ray diffraction (XRD) and morphology identification was done by scanning electron microscope (SEM); Electromagnetic properties and direct test of radar absorption of coatings were measured by Agilent E8362B and Agilent HP8510 Vector Network Analyzer (VNA) devices in X band, respectively. The simulation of coatings was done based on transmission line theory using the Nicholson-Ross-Weir algorithm and reflection loss relations in MATLAB software. The coatings were optimized in terms of four main manufacturing parameters: filler type, filler additive percentage, thickness, and manufacturing method. The coating made in 2 mm thickness has more than 90% radar absorption (less than -10 dB) with an absorption bandwidth of 3.3 GHz and more than 80% radar absorption (less than -7 dB) with an absorption bandwidth of 3.9 GHz absorption and the average radar absorption percentage was93.67% in the entire X-band, Also, the absorption frequency peak was -35.8 dB, 99.97% absorption was obtained.
