Microwave absorbing structure using periodic pattern coated fabric

In this study, a microwave absorbing structure consisting of a periodic pattern coated glass fabric (PPCF) and a glass-fiber/epoxy composite as the spacer is presented using a practical approach for application in aircraft. To fabricate a PPCF, a carbon-based conducting material bar coating device was used. To test the performance of the PPCF, an X-band (8.2-12.4 GHz) microwave absorbing structure was fabricated using an autoclave and measured using a free-space measurement system. The return loss of the fabricated PPCF microwave absorbing structure was -27 dB at the resonance frequency, and the measurement result was well matched with the simulation result. Since the pattern was implemented on an uneven surface, the performance stability of the distribution of sheet resistance on the surface, pattern spreading phenomena, and waviness of patterns was verified using a simulation method. The simulation result showed good performance stability. To verify the mechanical properties, an interlaminar shear strength (ILSS) test was performed. Since the pattern on the glass fabric can act in a similar way to a defect, there is a high probability of mechanical property degradation. However, the ILSS test results of the PPCF specimen was comparable with a pure glass-fiber/epoxy composite.