Dual-Band SIW Filter with Widely Separated Passbands Based on TE101 and TE301 Modes

In this paper, a novel dual-band substrate integrated waveguide (SIW) filter with widely separated passbands is presented, which is realized by dual-mode TE101 and TE301 resonances. To make the TE301 mode create the second passband, two novel techniques to suppress the TE201 mode are proposed and discussed. The proposed techniques excite the TE201 mode but either block its coupling path or cancel its effect at the output port, which can be identified as mode blocking and mode cancelling, respectively. They show a merit of introducing an extra transmission zero, which is beneficial to enhance the out-of-band rejection. To verify the concept, a dual-band filter prototype operating at 6.5 and 11 GHz is designed and fabricated, which shows a good electrical performance and a compact size.