基于线性电路的伪波形选择性超表面吸收器

Pseudo-Waveform-Selective Metasurface Absorber Based on Linear Circuits

超表面吸收器(MA)能吸收电磁波的能量,减少信号的反射或透射,在保护敏感电子器件免受电磁(EM)干扰方面具有重要作用。本文提出了一种基于方环形谐振器结构加载集总电阻的伪波形选择性超表面吸收器(PWSMA),其能够模拟非线性电路MA的波形选择特性,在同一工作频率实现连续波或长脉冲信号的强吸收、超短脉冲的低吸收。所设计的PWSMA基本单元由表层金属方环形谐振器结构加载集总电阻、中间介质隔离层和底部接地层组成。结果表明,该PWSMA对连续波在3.3 GHz的吸收率可达98.6%,而对应同频率下脉冲宽度为0.5 ns的超短脉冲吸收率只有43.9%,具有显著的连续波选择性吸收性能。这种基于线性MA的波形选择响应特性主要源于谐振器结构的色散行为,而不是非线性电路结构的全波整流和频率转换特性。PWSMA吸收率随着脉冲宽度的增大显著增强,当脉冲宽度增大到100 ns以上时,脉冲波吸收率达到98.3%,在整个频率范围内与连续波相近。另外,PWSMA对脉冲波和连续波吸收范围都不可能超过Rozanov极限。进一步结果表明,通过改变电阻值可以显著调节PWSMA对连续波和脉冲信号的吸收特性。

Metasurface absorbers(MA)can absorb electromagnetic(EM)wave energy,reduce signal reflection or transmission,and are crucial for protecting sensitive electronic devices from EM interference.This article proposes a pseudo-waveform-selective metasurface absorber(PWSMA)based on a square-ring resonator structure with a lumped resistor,which can simulate the waveform-selection characteristics of nonlinear MA,achieving strong absorption of continuous wave or long pulse signals and low absorption of ultrashort pulses at the same operating frequency.The designed PWSMA basic unit exhibits a surface metal square-ring resonator structure with lumped resistance and comprises an intermediate dielectric isolation layer and a bottom grounding layer.The results show that the PWSMA has an absorption rate of 98.6%for continuous waves with a frequency of 3.3 GHz,while for ultrashort pulses with a pulse width of 0.5 ns at the same frequency,the absorption rate is only 43.9%,indicating significant selective absorption performance for continuous waves.The waveform-selection response characteristics based on linear MA mainly originate from the dispersion behavior of the resonator structure rather than the full wave rectification and frequency conversion characteristics of the nonlinear circuit.The absorption rate of PWSMA significantly increases as the pulse width increases.In particular,when the pulse width exceeds 100 ns,the absorption rate of the pulse wave reaches 98.3%,which is similar to that of continuous waves across the entire frequency range.In addition,the PWSMA cannot exceed the Rozanov limit in terms of the absorption range for pulsed and continuous waves.Results indicate that changing the resistance value can significantly adjust the absorption characteristics of the PWSMA for continuous waves and pulse signals.