Design of a Dual-Band Balanced SIW Bandpass Filter with High Common-Mode Suppression

Abstract

A new dual-band balanced bandpass filter (BPF) is designed by taking advantage of the TE 102 -mode in substrate integrated waveguide (SIW) cavity in this paper. Good selective differential-mode (DM) transmission and quite high common-mode (CM) suppression can be realized with a wise arrangement of TE 102 -mode SIW cavities on the symmetrical plane. Besides, two independently controllable finite transmission zeros are introduced by the extracted-pole mechanisms to achieve flexible dual passbands. To demonstrate the design concept and theory, a prototype dual-band balanced BPF operating at 9.42 and 9.99 GHz has been designed, fabricated and measured. The measured CM rejection within the DM passbands is more than 41 dB. Both simulated and measured results are provided with reasonable agreement.