volume | PIER Journals

Abstract

This paper presents a compact dual-band bandpass filter, based on substrate integrated waveguide (SIW) technology, highlighting independent tuning abilities over center frequencies. Rectangular mushroom resonators (RMRs) are inserted inside an SIW cavity to realize the filtering structure, where two transmission bands are generated, which are centered at 2.4 GHz and 4.35 GHz, respectively by simultaneous employment of TE₁₀₁ and TE₂₀₁ resonant modes. Unlike conventional tunable dual-band filters, which generally exhibit interdependent frequency shifting between the operating bands, the proposed design employs an independent modal-tuning mechanism via selective perturbation of the resonant current paths. In the proposed methodology, radial and linear perturbation slots are strategically introduced at locations derived from modal electric field and surface current analyses to selectively modify the effective electrical length of separate resonant modes. One mode can be shifted without producing noticeable influence on the other by properly orienting these perturbation elements and thereby enabling isolated control of each passband while preserving the original cavity geometry. To obtain practical dual-band bandpass filtering performance cascaded RMR-loaded SIW resonators are configured into a highly selective filter topology. Metallic radial perturbation shafts are incorporated into the resonator structure to facilitate dynamic adjustment of slot exposure for real-time and post-fabrication tuning. Experimental verification confirms independent tuning of the lower passband from 2.0 GHz to 2.2 GHz, corresponding to around 9.5% frequency shift, while maintaining the upper band unchanged. Similarly, the upper passband is independently shifted from 4.0 GHz to 4.1 GHz, yielding close to 2.5% tuning range without affecting the lower band. The filter retains insertion loss under 2 dB over the full tuning range while exhibiting negligible compromise in passband selectivity. With its compact structure, low-loss characteristics, and independently reconfigurable capability, the proposed design is well suited for adaptive multiband microwave and wireless front-end implementations.

1. Chen, Xiao-Ping and Ke Wu, "Substrate integrated waveguide filter: Basic design rules and fundamental structure features," IEEE Microwave Magazine, Vol. 15, No. 5, 108-116, 2014.
doi:10.1109/mmm.2014.2321263 Google Scholar

2. Chen, Xiao-Ping and Ke Wu, "Substrate integrated waveguide filters: Design techniques and structure innovations," IEEE Microwave Magazine, Vol. 15, No. 6, 121-133, 2014.
doi:10.1109/mmm.2014.2332886 Google Scholar

3. Deslandes, D. and Ke Wu, "Accurate modeling, wave mechanisms, and design considerations of a substrate integrated waveguide," IEEE Transactions on Microwave Theory and Techniques, Vol. 54, No. 6, 2516-2526, 2006.
doi:10.1109/tmtt.2006.875807 Google Scholar

4. Chen, Xiao-Ping, Ke Wu, and Zhao-Long Li, "Dual-band and triple-band substrate integrated waveguide filters with Chebyshev and quasi-elliptic responses," IEEE Transactions on Microwave Theory and Techniques, Vol. 55, No. 12, 2569-2578, 2007.
doi:10.1109/tmtt.2007.909603 Google Scholar

5. Wang, Huan-Ying, Guo Hui Li, Yu-Dan Wu, Wei Yang, and Tong Mou, "A novel triple-band filter based on triple-mode substrate integrated waveguide," Progress In Electromagnetics Research Letters, Vol. 58, 59-65, 2016.
doi:10.2528/pierl15102601 Google Scholar

6. Xie, Hao-Wei, Kang Zhou, Chun-Xia Zhou, and Wen Wu, "Substrate-integrated waveguide triple-band bandpass filters using triple-mode cavities," IEEE Transactions on Microwave Theory and Techniques, Vol. 66, No. 6, 2967-2977, 2018.
doi:10.1109/tmtt.2018.2833462 Google Scholar

7. Tomassoni, Cristiano, Lorenzo Silvestri, Maurizio Bozzi, and Luca Perregrini, "Substrate-integrated waveguide filters based on mushroom-shaped resonators," International Journal of Microwave and Wireless Technologies, Vol. 8, No. 4-5, 741-749, 2016.
doi:10.1017/s1759078716000453 Google Scholar

8. Awasthi, Seema, Animesh Biswas, and Mohammed Jaleel Akhtar, "A CAD model of triple bandpass filter implemented with mushroom structure," International Journal of RF and Microwave Computer-Aided Engineering, Vol. 24, No. 4, 421-428, 2014.
doi:10.1002/mmce.20780 Google Scholar

9. Chaudhury, Soumit S., Seema Awasthi, and Rajat K. Singh, "Dual band bandpass filter based on substrate integrated waveguide loaded with mushroom resonators," Microwave and Optical Technology Letters, Vol. 62, No. 6, 2226-2235, 2020.
doi:10.1002/mop.32315 Google Scholar

10. Chaudhury, Soumit Samadder, Seema Awasthi, and Rajat Kumar Singh, "Independent control over resonating modes of mushroom resonator loaded substrate integrated waveguide using perturbation slots," 2019 IEEE Indian Conference on Antennas and Propogation (InCAP), 1-4, Ahmedabad, India, 2019.
doi:10.1109/InCAP47789.2019.9134530

11. Zhang, Qiao-Li, Sulav Adhikari, Bing-Zhong Wang, and Ke Wu, "A reconfigurable dual-mode bandpass filter based on substrate integrated waveguide," Microwave and Optical Technology Letters, Vol. 59, No. 4, 934-937, 2017.
doi:10.1002/mop.30434 Google Scholar

12. You, Bin, Shishi Lu, Long Chen, and Q. J. Gu, "A half-mode substrate-integrated filter with tunable center frequency and reconfigurable bandwidth," IEEE Microwave and Wireless Components Letters, Vol. 26, No. 3, 189-191, 2016.
doi:10.1109/lmwc.2016.2526031 Google Scholar

13. Lan, Bozhang, Chenjiang Guo, and Jun Ding, "A fully tunable two-pole bandpass filter with wide tuning range based on half mode substrate integrated waveguide," Microwave and Optical Technology Letters, Vol. 60, No. 4, 865-870, 2018.
doi:10.1002/mop.31058 Google Scholar

14. Anand, Akash, Joshua Small, Dimitrios Peroulis, and Xiaoguang Liu, "Theory and design of octave tunable filters with lumped tuning elements," IEEE Transactions on Microwave Theory and Techniques, Vol. 61, No. 12, 4353-4364, 2013.
doi:10.1109/tmtt.2013.2287674 Google Scholar

15. Zhou, Chun-Xia, Chuan-Ming Zhu, and Wen Wu, "Tunable dual-band filter based on stub-capacitor-loaded half-mode substrate integrated waveguide," IEEE Transactions on Microwave Theory and Techniques, Vol. 65, No. 1, 147-155, 2017.
doi:10.1109/tmtt.2016.2613053 Google Scholar

16. Nam, Seunggoo, Boyoung Lee, and Juseop Lee, "Reconfigurable bandpass filter topology using cul-de-sac resonators with adjustable notches," 2016 IEEE MTT-S International Microwave Symposium (IMS), 1-4, San Francisco, CA, USA, 2016.
doi:10.1109/MWSYM.2016.7539985

17. Lee, Boyoung, Seunggoo Nam, Beyoungyoun Koh, Changsoo Kwak, and Juseop Lee, "K-band frequency tunable substrate-integrated-waveguide resonator filter with enhanced stopband attenuation," IEEE Transactions on Microwave Theory and Techniques, Vol. 63, No. 11, 3632-3640, 2015.
doi:10.1109/tmtt.2015.2483495 Google Scholar

18. Sekar, Vikram, Marcelino Armendariz, and Kamran Entesari, "A 1.2-1.6-GHz substrate-integrated-waveguide RF MEMS tunable filter," IEEE Transactions on Microwave Theory and Techniques, Vol. 59, No. 4, 866-876, 2011.
doi:10.1109/tmtt.2011.2109006 Google Scholar

19. Sekar, Vikram and Kamran Entesari, "A half-mode substrate-integrated-waveguide tunable filter using packaged RF MEMS switches," IEEE Microwave and Wireless Components Letters, Vol. 22, No. 7, 336-338, 2012.
doi:10.1109/lmwc.2012.2199976 Google Scholar

20. Mira, Fermín, Jordi Mateu, and Carlos Collado, "Mechanical tuning of substrate integrated waveguide resonators," IEEE Microwave and Wireless Components Letters, Vol. 22, No. 9, 447-449, 2012.
doi:10.1109/lmwc.2012.2208735 Google Scholar

21. Mira, Fermin, Jordi Mateu, and Carlos Collado, "Mechanical tuning of substrate integrated waveguide filters," IEEE Transactions on Microwave Theory and Techniques, Vol. 63, No. 12, 3939-3946, 2015.
doi:10.1109/tmtt.2015.2490144 Google Scholar

22. Zhang, Hao, Wei Kang, and Wen Wu, "Balanced bandpass filter with tunable centre frequency based on substrate integrated waveguide technology," Electronics Letters, Vol. 54, No. 14, 886-888, 2018.
doi:10.1049/el.2018.0273 Google Scholar

23. Azad, Amit Ranjan and Akhilesh Mohan, "Single-and dual-band bandpass filters using a single perturbed SIW circular cavity," IEEE Microwave and Wireless Components Letters, Vol. 29, No. 3, 201-203, 2019.
doi:10.1109/lmwc.2019.2893379 Google Scholar

24. Nie, Hui, Bing Lan, Tiancheng Yu, Dongdong Liu, Xiaopeng Yu, Qun Jane Gu, and Zhiwei Xu, "A 1.3–1.7-GHz Q-enhanced resonator-based high-IF bandpass filter with 1.5%–67% tunable fractional bandwidth in 65-nm CMOS process," IEEE Transactions on Microwave Theory and Techniques, Vol. 72, No. 7, 4028-4042, 2024.
doi:10.1109/tmtt.2023.3342627 Google Scholar

25. Tang, Wei Sheng, Shao Yong Zheng, Yong Mei Pan, and Hai Wen Liu, "A frequency independently tunable dual-band bandpass filter with large frequency ratio and ultra-wide stopband," IEEE Transactions on Industrial Electronics, Vol. 70, No. 2, 1894-1904, 2023.
doi:10.1109/tie.2022.3161816 Google Scholar

26. Lin, Wentao, Kang Zhou, and Ke Wu, "Band-reconfigurable tunable bandpass filters based on mode-switching concept," IEEE Transactions on Microwave Theory and Techniques, Vol. 71, No. 3, 1125-1135, 2023.
doi:10.1109/tmtt.2022.3217483 Google Scholar

27. Jones, Thomas R. and Mojgan Daneshmand, "Miniaturized folded ridged quarter-mode substrate integrated waveguide RF MEMS tunable bandpass filter," IEEE Access, Vol. 8, 115837-115847, 2020.
doi:10.1109/access.2020.3004116 Google Scholar

28. Iqbal, Amjad, Arbab Waheed Ahmad, Amor Smida, and Nazih Khaddaj Mallat, "Tunable SIW bandpass filters with improved upper stopband performance," IEEE Transactions on Circuits and Systems II: Express Briefs, Vol. 67, No. 7, 1194-1198, 2020.
doi:10.1109/tcsii.2019.2936495 Google Scholar

29. Yan, Jun-Jie, Fu-Chang Chen, Kai-Ran Xiang, and Zhi-Hong Tu, "Design of tunable coaxial bandpass filters with constant absolute bandwidth using one tuning element," IEEE Transactions on Circuits and Systems II: Express Briefs, Vol. 71, No. 4, 1959-1963, 2024.
doi:10.1109/tcsii.2023.3331445 Google Scholar

30. Choi, Jin-Young, Jun-Seok Ma, and Wook-Sung Kim, "Tunable high-selectivity wideband bandpass filter using triple-mode stub-loaded resonators based on liquid crystals," IEEE Access, Vol. 13, 186090-186102, 2025.
doi:10.1109/access.2025.3625633 Google Scholar

31. Lin, Zhong-Chao, Yimin Liu, Liang Li, Jinbo Li, Jianzhong Chen, Junhua Xu, and Kai-Da Xu, "Dual-band bandpass filter with independently tunable attenuation characteristics using graphene nanoplates," IEEE Transactions on Plasma Science, Vol. 50, No. 12, 5031-5037, 2022.
doi:10.1109/tps.2022.3221190 Google Scholar

32. Hou, Rui, Jianzhong Chen, Yu-Tong Zhao, Tao Su, Liang Li, and Kai-Da Xu, "Varactor-graphene-based bandpass filter with independently tunable characteristics of frequency and amplitude," IEEE Transactions on Components, Packaging and Manufacturing Technology, Vol. 12, No. 8, 1375-1385, 2022.
doi:10.1109/tcpmt.2022.3195768 Google Scholar

33. Dyussembayev, Altynbek and Dimitra Psychogiou, "Continuously tunable 3-D printed helical resonators and bandpass filters using actuated liquid metals," IEEE Microwave and Wireless Components Letters, Vol. 32, No. 7, 855-858, 2022.
doi:10.1109/lmwc.2022.3152014 Google Scholar

34. Jeong, Seong-Wook, Gyuwon Lee, Jongheun Lee, and Juseop Lee, "Frequency-tunable absorptive bandpass filter using substrate-integrated waveguide structure," IEEE Transactions on Microwave Theory and Techniques, Vol. 69, No. 12, 5351-5359, 2021.
doi:10.1109/tmtt.2021.3119661 Google Scholar

35. Zhao, Kunchen, Roberto Gómez-García, and Dimitra Psychogiou, "Tunable quasi-reflectionless bandpass filters using substrate integrated coaxial resonators," IEEE Transactions on Circuits and Systems II: Express Briefs, Vol. 69, No. 2, 379-383, 2022.
doi:10.1109/tcsii.2021.3094991 Google Scholar

36. Chen, Zhen, Kaixue Ma, Yongqiang Wang, Ningning Yan, and Keping Wang, "A quad-operation-mode tunable SISL bandpass filter with compact size and self-packaging," IEEE Microwave and Wireless Technology Letters, Vol. 33, No. 4, 379-382, 2023.
doi:10.1109/lmwt.2022.3225655 Google Scholar

37. Cho, Young-Ho, Cheolsoo Park, and Sang-Won Yun, "0.7-1.0-GHz switchable dual-/single-band tunable bandpass filter using a switchable J-Inverter," IEEE Access, Vol. 9, 16967-16974, 2021.
doi:10.1109/access.2021.3052484 Google Scholar

38. Dong, Jiancheng, Kai Xu, and Jin Shi, "A voltage-controlled tunable differential dual-band bandpass filter with compact size and wide tuning range," IEEE Transactions on Industrial Electronics, Vol. 68, No. 10, 9952-9962, 2021.
doi:10.1109/tie.2020.3022516 Google Scholar

39. Nasser, Mohammed R. A. and Dimitra Psychogiou, "Switchless multi-octave tune-all BPF manifold using low-pass/high-pass diplexer junctions," IEEE Journal of Microwaves, Vol. 4, No. 4, 759-766, 2024.
doi:10.1109/jmw.2024.3421535 Google Scholar

40. Fan, Maoyu, Kaijun Song, Li Yang, and Roberto Gómez-García, "Frequency-tunable constant-absolute-bandwidth single-/dual-passband filters and diplexers with all-port-reflectionless behavior," IEEE Transactions on Microwave Theory and Techniques, Vol. 69, No. 2, 1365-1377, 2021.
doi:10.1109/tmtt.2020.3040481 Google Scholar

41. Wang, Qunliang, Yanfeng Jiang, and Yanxiong Wang, "Low-cost low-loss tunable dual-band filter using coupled lines with variable coupling coefficients," International Journal of RF and Microwave Computer-Aided Engineering, Vol. 2024, No. 1, 5668593, 2024.
doi:10.1155/2024/5668593 Google Scholar

Dr. Soumit Samadder Chaudhury

Mrs. Seema Awasthi

Dr. Rajat Kumar Singh