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http://dx.doi.org/10.5515/KJKIEES.2007.18.11.1217

Design and Performance Evaluation of Two-Layered Microwave Absorbers(Dielectric/Magnetic) for Wide Oblique Incidence Angles Used for ITS  

Kim, Jae-Woong (Dept. of Materials Engineering, Chungbuk National University)
Kim, Sung-Soo (Dept. of Materials Engineering, Chungbuk National University)
Publication Information
The Journal of Korean Institute of Electromagnetic Engineering and Science / v.18, no.11, 2007 , pp. 1217-1223 More about this Journal
Abstract
Advanced microwave absorbers for wide oblique incidence angles are required in many applications including wireless communication or vehicle identification in ITS(Intelligent Transport System) where 5.8 GHz DSRC(Dedicated Short Range Communication) system is applied. In this study, two-layered microwave absorber(with a laminate structure of dielectric/magnetic composites) has been designed for the achievement of low reflection coefficient over wide incidence angles at 5.8 GHz. Iron flake particles are used as the filler in the absorbing layer, and the magnetic composite sheet exhibits high magnetic loss due to ferromagnetic resonance in gigahertz frequencies. The surface layer of low dielectric constant containing small amount of carbon black is used as the impedance transformer. On the basis of transmission line theory, the reflection loss has been calculated for the two-layer structure with variation of incident angles for both TE(Transverse Electric) and TM(Transverse Magnetic) polarizations. At the optimum thickness of the composite layers, a low value of reflection loss(less than -10 dB) has been predicted for wide incidence angles up to $55^{\circ}$ which is in good agreement with the measured value determined by free-space measurement.
Keywords
Microwave Absorbers; Oblique Incidence; Iron Flakes; ITS;
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