A high-temperature radar absorbing structure: Design, fabrication, and characterization

In this investigation, a new sandwich structure called the SiCf/SiC sandwich radar absorbing structure (SRAS) for high-temperature radar absorption was designed using SiCf/SiC composites. Samples with the base design and optimized design were then fabricated through the PIP process, and the free space reflectivity was measured. The experimental result agrees with the calculated result, exhibiting excellent absorbing properties. The high-temperature reflectivity of the SiCf/SiC SRAS was also measured and the variation with temperature is found to be in a small range, indicating excellent absorbing properties at elevated temperatures. The factors determining the variation of reflectivity with temperature were also investigated, and the sheet resistance of the SiC fiber fabrics (particularly, the resistance characteristics of the pyrocarbon layer of the SiC fiber has a negative temperature coefficient) used as the lossy layer in the SRAS is found to be primarily responsible for the thermal variation of reflectivity.