Copyright © 2008 The Institute of Electronics, Information and Communication Engineers
Regular Section - Papers - Microwaves, Millimeter-Waves |
The Dual-Band Bandpass Filters Using Doubly Parallel-Coupled SIRs with Multiple Zeros for WLAN Applications
1 The authors are with the Graduate Instituite of Communications Eng. and Dept. of Electronic Eng., National Changhua University of Education, Taiwan. E-mail: ho{at}cc.ncue.edu.tw, 2 The author is with Wistron NeWeb Corp., Taiwan.
 |
Abstract |
|---|
Two dual-band bandpass filters (BPFs) based on the doubly parallel-coupled stepped impedance resonators (SIRs) structures have been proposed in this paper. The coupled-SIRs with/without open-stub-loads are introduced in the filter design. The dual-band filters exhibiting multiple zeros design operate at 2.45/5.2-GHz for the WLAN applications. Two three-staged filters composed of four SIRs have been proposed with the tapped-line adapted in the I/O sections. A five-staged filter is constructed based on the same design principle to achieve a better band-rejection. The proposed filters have the advantages of a much wider bandwidth in both the passbands without sacrificing the passband's insertion loss and passband flatness. The design procedure for a conventional parallel-coupled microstrip lines model is still suitable to design the proposed filters. The proposed filters have achieved almost twice the bandwidth of a conventional parallel-coupled lines configuration under the same design parameters. The experiments have been conducted to verify filter performance. Measured results are in good agreement with the full-wave simulation results.
Key Words: doubly parallel-coupling, multiple zeros assignment, dual-band BPF, WLAN
Manuscript received May 24, 2007. Manuscript revised January 27, 2008.