低频磁性吸波体设计与吸波性能

Design and absorption performance of a magnetic absorber for low-frequency

用超声混合法制备了一种片状羰基铁与粘结剂复合的微波吸收材料,根据0.1~18GHz频段材料的电磁参数和传输线理论可知,该复合物在低频段具有良好的吸波特性,然而,计算结果表明其吸收带宽未能全部覆盖S波段。因此,为了实现低频宽带吸波,基于测得的电磁参数,利用仿真软件进行了结构设计,并以此为指导制备了一种台阶状吸波体,在波导中利用短路法测量该样品的吸波性能。结果表明,在整个S波段,微波吸收率均可达到84%以上,相较传统单层吸波体,吸收带宽有效拓宽。此外,提出了一种物理模型并计算了这种台阶状吸波体的能量吸收率,实验结果与计算结果吻合较好。

A kind of microwave absorbing material is prepared by ultrasonic method that mixing flake-shaped carbonyliron with adhesive.The electromagnetic parameters of the material at frequency of 0.1 to 18 GHz and the theory of transmission lines reveal that the material has good absorption performance in low frequency.However,calculative results indicate that the absorption bandwidth can not cover the whole S-band.Therefore,in order to realize the target of broadband absorption at low frequency,it’s required to expand the absorption bandwidth.Based on measured electromagnetic parameters of the material,an optimized structure is obtained by simulation software.Besides,a step-like absorber based on simulation results is fabricated,and the absorption performance of the structural absorber is measured by waveguide at frequency of 2.6 to 3.95 GHz.Experimental results indicate that compared with the traditional single layer absorber,the bandwidth of less than–8 dB in S-band of step-like absorber has expanded greatly,which covers the whole S-band.In addition,a physical model is proposed to calculate the absorption ratio of this step-like absorber.Calculative results are close to fitting results of the absorption ratio.