电磁屏蔽用低频比小型化双频带频率选择表面

A miniaturized dual-band frequency selective surface with low frequency ratio for electromagnetic shielding

为满足敏感电子设备对频段密集相邻干扰信号的屏蔽需求,提出了一种低频比双频段带阻频率选择表面(FSS)结构。该结构由介质层和印刷在其两侧并谐振在不同频率的金属导带层构成。通过对两侧金属导带的互补型设计,削弱了两个谐振点间的耦合影响,使该FSS结构具有两个可以独立调节且紧密相邻的阻带,呈现出低频比特点。仿真结果表明,此结构可以实现低至1.16的谐振频率比。基于弯折结构的小型化设计使该FSS的单元尺寸仅为0.071λ,确保所提结构在TE和TM两种极化电磁波照射下,电磁屏蔽效能大于24 dB的入射角度稳定性高达60°。制作了实物并进行测试,实测结果与仿真结果吻合良好,验证了FSS结构设计的可靠性。

A miniaturized dual-stopband frequency selective surface(FSS)is proposed in this paper to shield the sensitive electronic equipment from interference signals with closely spaced frequency bands.The proposed FSS composes of a dielectric layer and two metal strip layers printed on both sides of the dielectric substrate.Different from other dual-band FSSes,the coupling between the double metal strip layers of the proposed FSS is weakened intentionally by using the complementary design of the strip patterns.As a result,the proposed FSS has two independently tunable stopbands which are very closely spaced.The simulated results show that the operating bands of the proposed FSS structure can achieve a frequency ratio as low as 1.16.In addition,the miniaturized design by using the convoluted elements makes the dimension of the unit cell as small as 0.071λ,whereλis the wavelength of the lower resonant frequency in free space.This ensures that the proposed FSS has incident angular stability of up to 60°for both TE and TM polarizations,while keeping at least 24 dB shielding effectiveness at the same time.The prototypes of the proposed FSS are fabricated and tested.Good agreements are achieved between the measurement and simulation,which demonstrates the reliability of the simulation.