Fabricate Rectangle-Patch and Square Notch Based 2.4/5.2GHz Dual-Band Bandpass Filter on Ceramic

The dielectric constant of traditional FR4 substrate (epsiv_r =4.4) is not big enough. So, it is not suitable for making the miniature microwave filter. In order to reduce the size, the Al₂O₃ ceramic with higher dielectric constant (epsiv_r = 9.4) can be used as the substrate to design the microwave filters. In this paper, the novel 2.4/5.2 GHz dual-band bandpass filters are proposed for WLAN (IEEE-802.Ha/b/g) applications. The filters are based on rectangle-patch resonators, square notches and two T-type input/output transmission lines. It is found that the length of patch and the size of notch will influence the insertion loss (S₂₁) and the resonant frequencies of the proposed bandpass filter. Because of the higher dielectric constant substrate and modify structure, the filters with optimized parameters exhibit good dual-band filtering performances and small size.