Ultra Wide Band Radar Cross Section Reduction of a Perfectly Electric Conductor Sphere by the Application of Multilayer Metamaterial Coatings (original) (raw)

2016, Journal of Microwaves, Optoelectronics and Electromagnetic Applications

A full-wave analytical method using the addition theorems and Hertzian potential functions are used to compute the radar cross section of a sphere coated by several layers composed of common materials and metamaterials. The minimization and maximization of radar cross section of a perfectly electric conductor sphere with such coatings are realized in a frequency band-width and in a wide interval of angles. One of the novelities of this contribution is, taking into dispersion relations of physically realizable metamaterials. So that the optimization procedure for RCS reduction is applied due to the coefficients describing dispersion characteristics. The method of least square is used for the design of a class of radar absorbing materials. The minimization of the error functions are performed by the combination of genetic algorithm and conjugate gradient method. It is shown that the proposed method of computation of radar cross section and its extremization effectively leads to the design of dispersive and isotropic metamaterials for the realization of radar absorbing materials.

Broadband Composite Radar Absorbing Structures with Resistive Frequency Selective Surface: Optimal Design, Manufacturing and Characterization

2017

A series of composite radar absorbing structures (RAS) with resistive frequency selective surface (FSS) have been designed and optimized in high efficiency using the transfer matrix method together with the adaptive genetic algorithm. The composite structures show broadband absorption property verified by both numerical simulation and experimental measurement. Especially, the optimal 5 mm-thick composite RAS inserted with a single layer of resistive FSS can produce 90% absorption bandwidth of around 11.8 GHz, which is much wider compared with the multilayered metallic metamaterial absorber with the same thickness. The composite RAS can be easily manufactured by dielectric substrates in combination with screen-printed resistive FSSs.

Design of New Metamaterial Absorber with Triple band for Radar Cross Section Reduction

— A new design for metamaterial absorber with triple band in X band range is proposed for Radar cross section reduction in stealth technology. The proposed metamaterial absorber has the advantage of ease design. It is a three layered structure, designed with modified ring resonators printed on a dielectric material with a metal ground. By proper tuning of the geometry parameters of the structure, a triple band metamaterial absorber is achieved and it is adjusted to match the effective impedance of metamaterial absorber to the free space. Hence, there is no wave transmission, minimized reflection and the absorption rate is maximized in all the bands. The resonant frequency bands are at 7.7 GHz, 9.2 GHz and 11.1 GHz with absorption rates of 99.7%, 98% and 94% respectively. The bandwidths measured at the triple band are 0.2757 GHz, 0.311 GHz and 0.2182 GHz. The total miniaturized metamaterial absorber unit cell size is 6 mm × 12 mm × 0.705 mm. Simulation results show that the proposed absorber with triple band and with high absorption rate is well suited for Radar cross section reduction in stealth technology.

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