Equiripple design of low‐pass filter using stub‐loaded Z‐shaped coupled‐line section. Issue 15 (14th November 2021)

• Record Type: Journal Article
• Authors: Huang, Xiaodong; Zhou, Yuting; Jin, Xiuhua; Yang, Liu; Cheng, Chonghu
• Is Part Of: IET microwaves, antennas & propagation. Volume 15:Issue 15(2021)
• Page Start: 1899
• Page End: 1913
• Publication Date: 2021-11-14
• Subjects: bandstop filter -- commensurate line -- coupled‐line -- equiripple filter -- low‐pass filter; Microwaves -- Periodicals; Microwave antennas -- Periodicals; Antennas (Electronics) -- Periodicals; Radio wave propagation -- Periodicals; Microwave communication systems -- Periodicals; 621.381305
• DOI: 10.1049/mia2.12204
• Languages: English
• ISSNs: 1751-8725

Abstract

Abstract: Design procedure of a novel transmission line low‐pass filter is presented. The filter has a flexible rejection response for a prescribed cut‐off frequency and an in‐band ripple factor. It is compact by using a Z‐shaped coupled‐line section, which is loaded with open‐circuited stubs. All of the transmission line elements are identical in electrical length, and the impedances can be calculated by solving certain specific equations according to prescribed in‐band specifications. The simulated results show that the circuit can generate low‐pass responses with third‐, fifth‐, and seventh‐order filtering functions. The filter order depends on the number and position of the loading stubs. For verification, two sample filters with cut‐off frequency of 0.5/0.3 GHz are fabricated using a three‐/five‐layer PCB process, which generate seventh‐order low‐pass filtering responses with good selectivity. The experimental results agree well with the predictions.