Design of Microstrip Lowpass-Bandpass Triplexer With High Isolation

Author

Fu-Chang Chen ; Jie-Ming Qiu ; Hao-Tao Hu ; Qing-Xin Chu ; Lancaster, Michael J.

Author_Institution

Sch. of Electron. & Inf. Eng., South China Univ. of Technol., Guangzhou, China

Volume

25

Issue

12

fYear

2015

Firstpage

805

Lastpage

807

Abstract

This letter proposes a lowpass-bandpass triplexer consisting of one lowpass channel and two bandpass channels. Stepped-impedance stubs are used in the lowpass filter (LPF) design, which bring a sharp selectivity. Defected ground structures are utilized to increase the impedance of one transmission line in the lowpass section, giving improved performance. High Isolation is achieved by careful consideration of the input signal splitting structure. To illustrate the concepts, a lowpass-bandpass triplexer is designed, fabricated and measured. The cut-off frequency of the LPF is chosen to be 1 GHz. The central passband frequencies are selected to be 2.4 and 5.8 GHz. Simulated and measured results are found to be in good agreement with each other. Isolations among the three bands are better than 40 dB.

Keywords

band-pass filters; low-pass filters; microstrip filters; microwave filters; multiplexing equipment; LPF design; bandpass channels; frequency 1 GHz; frequency 2.4 GHz; frequency 5.8 GHz; lowpass channel; lowpass filter design; microstrip lowpass-bandpass triplexer design; stepped-impedance stub; transmission line; Impedance; Low-pass filters; Passband; Transmission lines; Bandpass filter (BPF); high isolation; lowpass filter (LPF); microstrip; triplexer;

fLanguage

English

Journal_Title

Microwave and Wireless Components Letters, IEEE

Publisher

ieee

ISSN

1531-1309

Type

jour

DOI

10.1109/LMWC.2015.2496797

Filename

7332340