In this paper, a new compact size microstrip lowpass filter (LPF) with a very sharp roll-off is presented to apply in the modern wireless networks. The proposed LPF is designed using the series main resonators with meandered lines based on inductor-capacitor (LC) equivalent circuit analysis. The main goal is to achieve maximum-sharp roll-off by maintaining a wide stopband bandwidth and high return loss (RL). The main resonator of the proposed filter is consisted of two meandered line hairpin resonators (MLHR), and a meandered line T-shaped resonator (MLTR). The designed suppressor is composed of two coupled radial stubs to create a wide stopband. Low return loss in the passband, which has been created by the main resonator, is resolved by the suppressor structure with high return loss. The measured results show a − 3 dB cut-off frequency of 1.93 GHz. The very sharp transition band starts at 1.93 to 1.97 GHz (from − 3 to − 20 dB). The stopband is from 1.97 to 19.9 GHz (with the suppression level of − 20 dB). Also, the total size of the proposed LPF is only 13.3 × 10.1 mm².

在本文中，提出了一种新型的紧凑型微带低通滤波器（LPF），其滚降非常明显，可应用于现代无线网络。基于电感-电容器（LC）等效电路分析，使用具有弯曲线路的串联主谐振器设计提出的LPF。主要目标是通过保持较宽的阻带带宽和高回波损耗（RL）来实现最大锐利滚降。所提出的滤波器的主谐振器由两个曲折线发夹形谐振器（MLHR）和一个曲折线T形谐振器（MLTR）组成。设计的抑制器由两个耦合的径向短截线组成，以创建宽阻带。由主谐振器产生的通带中的低回波损耗由具有高回波损耗的抑制器结构解决。测量结果显示− 3 dB截止频率为1。93 GHz。非常陡峭的过渡带始于1.93至1.97 GHz（从− 3至− 20 dB）。阻带范围为1.97至19.9 GHz（抑制水平为− 20 dB）。另外，建议的LPF的总尺寸仅为13.3×10.1 mm²。