The current paper describes the design of a fourth-order compact narrow-band hairpin-line bandpass filter centered at 2.5 GHz and enhanced stopband suppression ~38 dB required for wireless local area network (IEEE802.11b). The size reduction of 24% has been achieved for a conventional hairpin-line filter with a second-order inward folding of the open-end arms with an improvement in the skirt characteristics. However, the folding mechanism has been overshadowed by the presence of spurious harmonics with an attenuation level of <10 dB. Subsequently, L-shaped spurlines with optimum dimensions have been incorporated in the coupled arms of the folded hairpin-line cells. Three fourth-order filters have been designed with the incorporation of spurlines in different coupling regions, fabricated, and tested experimentally. Accordingly, an extended stopband with a rejection level of 38 dB up to 4.48f0 and a size reduction of 18% over the conventional hairpin-line filter has been achieved.

目前的论文描述了一种四阶紧凑型窄带发夹线带通滤波器的设计，中心频率为 2.5 GHz，无线局域网 (IEEE802.11b) 所需的增强型阻带抑制约为 38 dB。传统的发夹线过滤器的尺寸减少了 24%，开口臂的二阶向内折叠并改善了裙边特性。然而，折叠机制已被衰减水平 <10 dB 的杂散谐波的存在所掩盖。随后，具有最佳尺寸的 L 形花键已被纳入折叠发夹线单元的耦合臂中。已经设计了三个四阶滤波器，在不同的耦合区域中加入了支线，并进行了制造和实验测试。因此，f 0并且与传统的发夹线过滤器相比，尺寸减小了 18%。