ABSTRACT
The paper presents a simple method to design a tri-band bandpass filter (BPF) using only two pairs of open-loop uniform impedance resonators (OLUIRs). The three passbands can be designed independently by selecting the lengths of two pairs of the OLUIRs. The design procedure is described in this paper. A tri-bandpass filter example is designed at 1.93, 2.6 and 3.9 GHz that can be applied to digital enhanced cordless telecommunications (DECT) and worldwide interoperability for microwave access (WiMAX). By means of the cross-coupling effect with different coupling paths, several transmission zeros appear near the passbands, thus enhancing the selectivity of the passbands. The measured results of the fabricated tri-BPF match the simulated results and confirm the design concept.
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Notes on contributors
Min-Hang Weng
Min-Hang Weng received the B.S., M.S., and Ph.D. degrees in electrical engineering from the National Cheng-Kung University, Tainan, Taiwan, in 1994, 1996, and 2000, respectively.
Che-Wei Hsu
Che-Wei Hsu received the B.S. degree in electrical engineering from I-Shou University, Kaohsiung, Taiwan, in 2012 and M.S. degree in Material Science and Engineering from National Pingtung University of Science and Technology, Pingtung, Taiwan in 2015.
Yuanmo Lin
Yuanmo Lin received the B.S. degree in electronic information engineering from Fuzhou University, Chian, in 2007, and M.S. degree in communication and information system from Shantou University, Chian, in 2010.
Chin-Yi Tsai
Chin-Yi Tsai received the B.S. degree in vehicle engineering, in 2018 and is now a M.S. student in Material Science and Engineering from National Pingtung University of Science and Technology, Pingtung, Taiwan.
Ru-Yuan Yang
Ru-Yuan Yang received the B.S. degree in Chemistry from National Taiwan normal university, Taipei, Taiwan, in 1996 and M.S. degree in Material Science and Engineering from National Sun Yat-Sen University, Kaohsiung, Taiwan in 2000, and Ph.D. degree in the Department of Electrical Engineering of National Cheng-Kung University, Tainan, Taiwan, in 2007.