A study of the nanocomposite sandwich structures for broadband microwave absorption and flexural strength

Composite sandwich structures are devised to work in a wide frequency of the microwave band. The microwave absorbing properties of composite sandwich structures are studied in 2-18GHz frequency band. The sandwich structures were manufactured from E-glass fiber/epoxy composites filled with carbon nano-materials and para-aramid honeycomb cores. The complex permittivity of E-glass/epoxy nanocomposites and adhesive films are determined in 8-12GHz frequency range using free-space measurement setup. The complex permittivity data were used to design the sandwich structures by varying composition and thickness of nanocomposite sheets using a simulation tool Computer Simulation Technology Microwave Studio. In the designing process, the thickness of honeycomb sheets was also varied to get best spacer thickness for the cancellation of reflected and transmitted microwaves. The simulated and measured results have shown that the designed structure can be used for -10dB Reflection coefficient over a wide frequency ranges in the microwave region. The results of flexural strength of the sandwich structure and tensile strength of facing sheets are also presented.