![]() The transmission can be eliminated by containing the copper in the bottom layer. and are the scattering parameters of the reflection and transmission respectively. The absorption ( A) of the metamaterial absorber is defined as in which and T and R represent the transmission and reflection coefficients. In the boundary condition setting, the x and y directions are set as = 0 or = 0 and z directions as an open(add space) respectively to obtain the reflection coefficient under two different polarization modes. In the CST simulation, two waveguide ports are added for transmitting and receiving electromagnetic waves. The simulation results are acquired by simulation software, CST Microwave Studio, which is based on the Finite Integration Time(FIT) domain method. The metal-cross shaped metamaterial dihedral (MCMD), cross-cross shaped metamaterial dihedral (CCMD) of the experimental samples and the measurement set-up are shown in figures 1(c), (d) and 2(b), respectively. ![]() Four flat plates of the same structure are composed of two dihedral corner reflector, whose middle gap are attached with copper film and the corner angle can be varied freely. The whole experimental sample is made into a unit size of 20 × 20 with 200 mm × 200 mm and a part of the sample is shown in figure 1(b). 2. Simulation and experimentįigure 1. (a) Unit cell of the cross structure, (b) the upper view of the experimentally realized sample (CMD), (c) the upper view of the experimentally realized sample (MCMD), (d) the upper view of the experimentally realized sample (CCMD). At last, the resonance frequency of RCS is compared with the absorption frequency to validate the method. The second part deals with the RCS of different dihedral corner reflectors loaded with a cross-shaped metamaterial structure. The absorption characteristics of the different polarization angles with TE and TM modes are verified by experiments. Firstly, the absorptivity of different dihedral corner reflectors with an open background has been calculated using the Finite Integration Technique. The dihedral corner absorbers exhibit a high absorption rate at different polarization incidences compared with a flat plate. This paper deals with the study of the absorbing characteristics of different dihedral corner structures. A major ignorance of traditional dihedral corner research is that many kinds of research focus on the RCS of dihedral corner but neglect the absorption property. It is analyzed in that RCS characteristics of dihedral corner reflectors caused by length is slighter than the effects caused by width. A method is presented to calculate the scattering characteristics of the dielectric coated corner reflector. For instance, the fractal structure or metasurface to enhance and reduce RCS has been proposed through the corner reflector. Most traditional studies have focused on the enhancement or reduction of Radar Cross section (RCS) in dihedral corner reflector. Besides, its wide scattering pattern makes it a typical scattering structure. Dihedral corner is one of the corner reflectors with strong multiple scattering characteristics. Dihedral corner, which is often formed between the plane's tails or between the naval ships and the water surface, could degrade the target's stealth performance. The dihedral corner, as a potential application of metamaterial absorber, has been rarely investigated. During the last years, many kinds of metamaterial absorbers have been extensively investigated: the stair-like 3D structure, multi-metallic-layers structure, flexible and lightweight substrate, planner structure, transparently curved metamaterial and so on. MPA can be applied in many fields, such as solar energy, plasmonic sensors, bolometers and photo-detectors. Metamaterial perfect absorbers(MPA) have been proposed at microwave by Landy et al in 2008. It obtains the properties which cannot be found in nature, such as negative refraction index, cloaks, superlens and extraordinary optical transmission. Metamaterials(MMs) are artificial effective electromagnetic structures with subwavelength scale cells.
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