This letter presents a novel narrow-band bandpass spoof surface plasmon polarition (SSPP) filter, which has a controllable passband, good rejection, and a compact structure. It is composed of two end-extending SSPP transmission lines and a pair of L-shaped coupling branches. Both the bandwidth and the central frequency can be adjusted by changing the depth of the SSPP unit and the length of SSPP transmission line behind the coupling branches. The dispersion curves of the SSPP unit are analyzed, and the influences of some structural parameters are investigated. A SSPP band-pass filter is fabricated and measured based on the proposed method, showing a wide 3-dB fractional bandwidth of 11.2% centered at 6.25 GHz and an out-of-band rejection below −15 dB within 1–10 GHz. The measured result shows good agreement with the simulated one.

中文翻译：

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使用欺骗表面等离子体激元的紧凑型窄带带通滤波器

这封信提出了一种新颖的窄带带通欺骗表面等离子体极化（SSPP）滤波器，它具有可控的通带、良好的抑制和紧凑的结构。它由两条末端延伸的SSPP传输线和一对L形耦合分支组成。带宽和中心频率都可以通过改变SSPP单元的深度和耦合分支后面的SSPP传输线的长度来调整。分析了SSPP装置的频散曲线，研究了一些结构参数的影响。基于所提出的方法制造和测量了 SSPP 带通滤波器，显示出以 6.25 GHz 为中心的 11.2% 的宽 3-dB 分数带宽和在 1-10 GHz 内低于 -15 dB 的带外抑制。测量结果与模拟结果吻合良好。