Novel X-band Microwave Absorber Based on Carbon Nanofiber Integrated with the FSS Structure for RCS Reduction of Strategic Targets

This paper presents the design of a novel ultrathin hybrid microwave absorber working in the X-band for stealth and other electronic countermeasure applications in order to reduce the radar cross section (RCS) of strategic targets. The proposed hybrid absorber is obtained by integrating the ring shaped frequency selective surface (FSS) structure with the carbon nanofiber (CNF) composite sheet. The hybrid absorber is simulated in CST software in order to achieve the enhanced absorption bandwidth using minimum sample thickness. The FSS structure with the ring shaped unit cells is first designed over the FR4 substrate in order to compute the reflection loss in the specified frequency band. In the next step, the carbon nano fiber composite is fabricated using varying weight percentages [1% and 3%] of CNF in the epoxy matrix. The dielectric properties of synthesized CNF nanocomposite samples are retrieved using the vector network analyzer under the waveguide environment. It is observed that a thin sample of neither the thin FSS structure nor that of the CNF nanocomposite is adequate enough to provide the required absorption bandwidth. Hence, a novel hybrid absorber is finally obtained by integrating the FSS structure with the CNF composite backed by a metallic sheet and simulated in CST which provides minimum reflection coefficient of -23.50 dB and -10 dB absorption bandwidth of 0.45 GHz using the overall sample thickness of only 1.5 mm.