嵌入分形频率选择表面的低频超薄吸波层的设计

摘要

研究了频率选择表面对超薄多层微波吸波体在低频(L和S频段)吸波性能的影响.分别采用硫化工艺和激光刻蚀方法制备出传统的微波吸收材料(MAM)——橡胶板和FSS层,然后利用它们合成多层微波吸波体(MMA)样品,在NRL弓形法测试系统中测量该样品的反射率.发现随着FSS层在传统吸波材料层中的引入,确实可以增强整个多层吸波体在低频段的吸波性能.实验结果显示,当两个FSS层在多层吸波体中适当排列时,可以在1 GHz得到一个-3.49 dB的反射率峰值,最大反射峰值可达-9.35 dB,这时的样品厚度是1.8 mm.本研究为吸波材料的吸波性能向低频段的拓展提供了一种有效的方法.%Ultra-thin absorbers at low frequency bands composed of two traditional microwave absorbing material (MAM) rubber plates and fractal frequency selective surface (FSS) were designed.The absorbing properties of composite absorbers of different arrangement of MAM and FSS were investigated in detail in L and S bands.Two traditional MAM rubber plates and fractal FSS layers were fabricated for producing the multilayer microwave absorber (MMA) samples by using vulcanizing and laser etching methods,respectively.The reflectivity of MMA samples were measured by the NRL-arch testing systems.It is found that introducing FSS layers into the traditional MAM plates indeed could strengthen the absorbing properties of MMA samples at low frequencies.Moreover,after proposing double FSS layers in a proper arrangement,the MMA sample with the thickness of only 1.8 mm could obtain peak value of -9.35 dB and the reflectivity value of-3.49 dB at 1 GHz,respectively.As a result,the introduction of fractal FSS layers could provide another way to develop the absorbing properties at low frequency bands.