short carbon fibers for broadband radar cross section reduction

Radar cross-section is one of the famed techniques of measuring electromagnetic scattering. In design of low visibility targets, reduction of electromagnetic scattering becomes vital. Furthermore, this technique employs absorbing materials including: carbon nanotubes, carbon black, carbon foam and carbon fibers, most of which have been intensely researched on regarding the single absorption function. Alternatively, an improvement of the functions of these materials has been to integrate their absorption capability with other functions. Carbon fiber-based composites have emerged as the most promising with regard to the multifunctional absorbance. However, accurate prediction of electromagnetic response of the composite materials has sparked several debates pertaining to the optimized absorption properties. Additionally, there is need to clarify further on the broadening of the bandwidth of the carbon fiber absorbing material.

Yongqiang Pang and Zhuo Xu from Xi’an Jiaotong University in collaboration with Yongfeng Li, Jiafu Wang, Mingbao Yan , Hongya Chen , and Shaobo Qu from Air Force Engineering University, Xi’an with Liangkui Sun from China Aerodynamic Research and Development Center developed an alternative method that could be exploited in place of the current techniques for the carbon fibers to achieve radar cross-section reduction over a broad frequency band. They focused on the utilization of materials made of conventional glass fabric composites loaded with a small number of carbon fibers. Their work is currently published in the research journal, Composites Science and Technology.

The research method employed entailed utilization of carbon fibers in the form of short yarns embedded in the surface layers of the composites, behaving as resonators and producing a phase difference from the pure glass fabric composites. The authors then investigated the influence of both the phase and loss on the radar cross section reduction performance. They then proceeded to simulate the chessboard and random structural configurations numerically and latter measured them experimentally.

The authors observed that the proposed composites allowed for remarkable suppressing of the specular scattering over a broad frequency band. Moreover, they noted that the designed radar cross section reduction level of more than 10 decibels covered the frequency range from 8.7 to 19.2 gigahertz, while the overall thickness utilized was 2.7 millimeters.

Yongqiang Pang and colleagues study presented a demonstration that proved that the widely-used glass fabric composites can be functionalized by a small number of carbon fibers for broadband radar cross section reduction. It was observed that unlike the conventional carbon fiber -based absorbers, the radar cross section reduction of the proposed technique was caused by the phase cancellation mechanism. Additionally, the carbon fiber-based resonator was observed to provide an abrupt phase change. Altogether, the proposed composites are of a simple configuration and robust for the defects. It is also expected that this work will act as a stepping stone for the extension of the same in curved surfaces.