ABSTRACT

The present paper describes the design of a folded hairpin-line bandpass filter centred at 2.5 GHz applicable for Wireless Local Area Network (WLAN) with improved spurious suppression. The size of the conventional filter has been reduced by 30% by folding the open-end arms towards the inward direction. Thus, improvements over the skirt characteristics and shifting of the second harmonic to higher frequency region have been obtained. However, the attenuation level at the harmonic frequency remains almost unaffected. Subsequently, the inner and outer edges of the coupled-lines have been modified with Minkowski fractals to compensate for the modal phase velocities. As a result, more than 36 dB of harmonic suppression up to three times the centre frequency along with size reduction of 30% has been achieved.

摘要

本论文描述了一种以 2.5 GHz 为中心的折叠发夹线带通滤波器的设计，该滤波器适用于具有改进的杂散抑制的无线局域网 (WLAN)。通过将开口臂向内折叠，传统过滤器的尺寸减小了 30%。因此，已经获得了对边缘特性的改进以及二次谐波向更高频率区域的偏移。然而，谐波频率处的衰减水平几乎不受影响。随后，耦合线的内边缘和外边缘已用 Minkowski 分形修改以补偿模态相速度。结果，实现了高达 3 倍中心频率的超过 36 dB 的谐波抑制以及 30% 的尺寸减小。