Development and Characterization of Carbon-Fiber Based Magnetically Loaded Microwave Absorber Material

Shielding of electronic devices is important for reasons ranging from regulatory to proper device functioning, and in applications from defense to consumer electronics. We report on the development and characterization of a novel microwave absorber material based on micron-sized ferrite beads and mm-length carbon fibers which are deposited electrostatically using the flocking process. The material is thin, lightweight, broadband and customizable with respect to frequency and amount of absorption. Absorber was characterized in X-band using NRL Arch Reflectivity measurements and it exhibited broadband attenuation ranging from around -10 dB at the edges of X-band to a peak of -46 dB at 11.1 GHz, which compares favorably with existing commercial solutions. Absorber permittivity and permeability were extracted using waveguide measurements for incorporation into EM simulations. It was determined that attenuation comes from both electric and magnetic field losses. Entire characterization process was verified by comparison with known absorber material and good agreement was found.