A novel dual-mode dual-band bandpass filter (BPF) for a single substrate configuration is proposed that uses a balun structure. The outer and inner loop resonators are simultaneously excited by the microstrip line and slotline balun structure. In spite of the microstrip feed network, the proposed dual-mode BPF can achieve dual-band operation. Two proper degenerate modes in the lower and upper passbands can be generated and controlled by installing an inductive cut and a capacitive patch in the corner of two loops, respectively. This letter deals with the analysis and design of the proposed dual-band BPF as well as the experimental validation of the predicted dual-band performance.
Bibliographical noteFunding Information:
Manuscript received March 12, 2010; revised May 31, 2010; accepted July 12, 2010. Date of publication August 26, 2010; date of current version November 05, 2010. This work was supported by the National Research Foundation of Korea Grant funded by the Korean Government [NRF-2009-352-D00224].
- Balun structure
- bandpass filter (BPF)
- dual-band filter
- dual-mode filter
- single substrate configuration
ASJC Scopus subject areas
- Condensed Matter Physics
- Electrical and Electronic Engineering