叠加Y环单元频率选择表面的设计

摘要

对Y环单元进行改造得到了叠加Y环单元图形,以延迟频率选择表面(FSS)的高次谐振,实现无干扰的单通带滤波器.运用谱域法分析得到的叠加Y环单元,并与Y环单元进行对比,分别讨论其角度稳定性、极化稳定性、-3 dB带宽和高次谐振点.分析表明:当中心频点同为17.6 GHz时,叠加Y环单元具有更窄的带宽,而高次谐波向后延迟6.5GHz,并保证了良好的极化稳定性和角度稳定性.叠加Y环单元臂长从2.78mm增大到3.18 mm时,中心频率从17.6GHz下降到14.1 GHz;臂宽从1.1 mm增大到1.5 mm时,中心频率从17.6 GHz提高到20.6 GHz,带宽变大；单元间距从7.2 mm增加到8 mm时,带宽从4.5 GHz减小到3.5 GHz,中心频点不变；缝隙宽度增大时,带宽变大,中心频点升高.在微波暗室中对叠加Y环单元FSS进行测试,结果与预期一致.结果表明,叠加Y环单元在保证角度稳定性与极化稳定性前提下,能够延迟高次谐振点,为工作频段内实现单通带滤波器提供了新的思路.%An overlapping Y loop element Frequency Selective Surface(FSS) based on traditional Y loop elements was designed to delay the high harmonics of FSS in a working band and to achieve the single-pass band filter. By using the spectrum domain approach, the new element was analyzed and compared with the traditional Y loop elements. The affect of different incidence angles on the center frequency , - 3 dB bandwidth and the limitation ability for the high harmonics under TE and TM incidence waves was discussed. The results show that the new element FSS owns the good stability under different incidence angles and polarizations. In the same resonant frequency of 17. 6 GHz,the overlapping Y loop element possesses the narrower bandwidth than Y loop element, and its high harmonics delays for 6. 5 GHz. When the length of the arm grows from 2. 78 mm to 3. 18 mm, the center fre quency descends from 17.6 GHz to 1 4 . 1 GHz ; When the width of the arm grows from 1 . 1 mm to1. 5 mm, the center frequency rises from 17. 6 GHz to 20. 6 GHz and the bandwidth is widened at the same time. Furthermore, when the space between the elements increases from 7. 2 mm to 8 mm, the bandwidth narrows down from 4. 5 GHz to 3. 5 GHz with a stable center frequency. The overlapping Y loop element FSS was tested in a microwave darkroom. By comparing with a calculation, the measured curve is good agreement with the calculated one. Obtained results show that the overlapping Y loop element can delay high harmonics in good stability for incidency angles and polarizations and provides a new idea for achieving the single-pass band filter in the working band.