The Miniature 2.4/5.2 GHz Dual-Band Bandpass Filter with Modified Hairpin Structure

A compact dual-band bandpass filter is designed to operate at 2.4/5.2 GHz without any input/output impedance matching. This filter is constructed of three resonators which are based on the stepped impedance resonators and hairpin resonators. The Al
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ceramic with a thickness of 0.6 mm and a relative dielectric constant of 9.4 was adopted as substrate. It is easy to be integrated with other RF circuits by SOP (System on Package) process. The three-order dual-band bandpass filter is optimally designed and its properties are confirmed by experiment. By the high dielectric constant substrate and modified structure, the optimized device exhibits excellent dual-band filtering performances and small size. The size of the proposed filter can be reduced about 32.5% in comparing to the typical hairpin filters.