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A stretchable microwave metamaterial absorber with specific pattern design is proposed and fabricated in this paper to improve the stability of microwave absorption for deformation. Compensation mechanism is revealed by the electrical current loop for resonance absorption excitation in an equivalent circuit model. The proposed metamaterial absorber with a slotted cross pattern is compared with the conventional cross pattern absorber. A stretchable silver conductive ink validates the silk screen printing of resistive patterns on flexible polydimethylsiloxane substrate and hence realizes the stretching experiments. In a 25% stretch, the resonant frequency of the compensated absorber shifts only 0.5% for TM polarization, comparing to the 8% shifting of the conventional structure. [ABSTRACT FROM AUTHOR]

Microwave absorbing honeycomb composites with grading coating thickness are prepared by impregnation of aramid paper frame within water solutions of conductive carbon blacks. Based on effective medium method, grading impedance in the composites can be theoretically expressed by a linear approximation of the inversely tapered effective permittivity at wave propagation direction, which provides a feasible way to optimize the design of microwave absorbing honeycomb structures. The consistent result of calculations and experimental measurements for positive impedance grading design confirms the broadband absorption effect in high frequencies. [ABSTRACT FROM PUBLISHER]

Radar absorbing honeycomb composites with different coating thicknesses are prepared by impregnation of aramid paper frame with solutions containing conductive carbon blacks (non-magnetic) and PI (polyimide). Expressions for the effective permittivity of the composites are studied and validated both in theory and experiment. It is found that a theoretical equivalent panel with given permittivity can be obtained to represent the honeycomb structure in the quasistatic approximation, which provides a feasible way to optimize the design of radar absorbing honeycomb structure by connecting the effective electromagnetic parameters with the unit cell dimensions. The effective permittivity is measured by a network analyzer system in the frequency range of 8–12 GHz and compared with the theoretical result. [ABSTRACT FROM PUBLISHER]