A bandstop filter is proposed, where the resonant element is a slot that is folded to the shape of the letter U and embedded into the microstrip line so that no extra width is required. Moreover, the folding of the slot reduces its length to ¼ the effective wavelength. This is a considerable size reduction in comparison with the filters using the resonant elements like rings or coupled short-circuited and open-circuited stubs. The designed prototype at the WLAN frequency of 2.45 GHz was investigated using the CST software package and showed low insertion loss at the passbands and high rejection across the stopband. The folding of the slot offered very low radiation at the stopband. The simulation results are validated by measurements on the fabricated prototypes.

提出了一种带阻滤波器，其中谐振元件是折叠成字母 U 形状并嵌入微带线中的槽，因此不需要额外的宽度。此外，槽的折叠将其长度减少到有效波长的 1/4。与使用谐振元件（如环或耦合的短路和开路短截线）的滤波器相比，这是一个相当大的尺寸减小。使用 CST 软件包对 2.45 GHz WLAN 频率下设计的原型进行了研究，结果表明通带插入损耗低，阻带抑制率高。槽的折叠在阻带处提供了非常低的辐射。通过对制造的原型进行测量来验证仿真结果。