Multi-band microwave filters are important for multifunctional and miniaturization requirement of portable communication equipment. In this paper, tri-section split ring stepped-impedance resonator is analyzed, and new compact dual-band and tri-band bandpass filters are proposed by using split ring stepped-impedance resonators, and the designs are demonstrated by measurement. The new dual-band filters operate at about 2.4 and 5.5 GHz which meet IEEE 802.11 application requirements, and the new tri-band filters operate at about 2.4-2.6, 3.3-3.6 and 5.2-5.6 GHz, and filter sizes are greatly reduced compared with relative reports. The designed filters have advantages of compact and miniature structures, low passband insertion losses and good frequency selectivity, all these have prospect to be applied in wireless communication systems.
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