Miniaturized Dual-Band Filter Utilizing Stacked Dual-Mode Patch-loaded SIW Cavity

In this paper, a miniaturized dual-mode dual-band bandpass filter (BPF) with controllable frequency ratio based on patch-loaded substrate integrated waveguide (PSIW) cavity is proposed. In order to realize the dual-band bandpass filter, two metallized blind vias are introduced along the symmetrical plane to provide an additional mode nominated as LC mode. By utilizing the additional mode and TEM
₀₀₁
mode in PSIW cavity, dual-band bandpass response is achieved. Moreover, the introduced blind vias can make frequency shifting of LC mode while not affect TEM
₀₀₁
mode. As a result, the frequency ratio of the two passbands can be controlled. For demonstration, a dual-band filter operating at 1.09 and 3.58 GHz is designed, fabricated and measured. The insertion losses are measured to be 1.24 dB and 2.23 dB with the measured return losses better than 17 dB.