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International Journal of Antennas and Propagation
Volume 2013 (2013), Article ID 852035, 5 pages
http://dx.doi.org/10.1155/2013/852035
Research Article

A Novel Triple-Mode Bandpass Filter Based on a Dual-Mode Defected Ground Structure Resonator and a Microstrip Resonator

1School of Information Engineering, East China Jiaotong University, Nanchang 330013, China
2State Key Laboratory of Millimeter Waves, Southeast University, Nanjing 210096, China
3School of Software and Communication Engineering, Jiangxi University of Finance and Economics, Nanchang 330032, China

Received 21 February 2013; Accepted 25 March 2013

Academic Editor: Haiwen Liu

Copyright © 2013 Xuehui Guan et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

A novel triple-mode bandpass filter (BPF) using a dual-mode defected ground structure (DGS) resonator and a microstrip resonator is proposed in this paper. The dual-mode characteristic is achieved by loading a defected T-shaped stub to a uniform impedance DGS resonator. A uniform impedance microstrip resonator is designed on the top layer of the DGS resonator and a compact bandpass filter with three resonant modes in the passband can be achieved. A coupling scheme for the structure is given and the coupling matrix is synthesized. Based on the structure, a triple-mode BPF with central frequency of 2.57 GHz and equal ripple bandwidth of 15% is designed for the Wireless Local Area Network. Three transmission zeros are achieved at 1.48 GHz, 2.17 GHz, and 4.18 GHz, respectively, which improve the stopband characteristics of the filter. The proposed filter is fabricated and measured. Good agreements between measured results and simulated results verify the proposed structure well.