volume | PIER Journals

Abstract

An innovative ceramic filter is presented in this paper. The filter is composed of six tuning apertures, coupling channels, and a six-blind-hole coupling structure. The six blind holes are divided into two groups: one situated between the first and second cavities to induce inductive coupling, and the other positioned between the second and third cavities to facilitate capacitive coupling. Employing this structure facilitates the formation of a cascade quadruple (CQ) coupling unit among the 1, 2, 3, and 4 resonant cavities, thereby introducing two transmission zeros. Subsequently, an analysis of the influences of the depth and spacing of each blind hole on the coupling coefficients is presented. Finally, to further validate the theory, the filter tailored for base station applications was designed and implemented. The measurement results demonstrate a center frequency of 3.5 GHz with a bandwidth of 200 MHz. In the passband, the insertion loss was below 1.2 dB, and the return loss surpassed 19 dB. The test outcomes align closely with the simulation, confirming the reliability of the design.

1. Wang, Xuguang, Geonho Jang, Boram Lee, and Namshin Park, "Compact quad-mode bandpass filter using modified coaxial cavity resonator with improved Q-factor," IEEE Transactions on Microwave Theory and Techniques, Vol. 63, No. 3, 965-975, Mar. 2015.

2. Chen, Fatang, Xiu Li, Yun Zhang, and Yanan Jiang, "Design and implementation of initial cell search in 5G NR systems," China Communications, Vol. 17, No. 5, 38-49, May 2020.

3. Liu, Sanjun and Guangming Gan, "Novel DDS based OFDM transmitter structure without IFFT and interpolation filter," China Communications, Vol. 18, No. 12, 219-229, 2021.

4. Carceller, C., F. Gentili, W. Bösch, D. Reichartzeder, and M. Schwentenwein, "Ceramic additive manufacturing as an alternative for the development of miniaturized microwave filters," 2017 IEEE MTT-S International Microwave Workshop Series on Advanced Materials and Processes for RF and THz Applications (IMWS-AMP), 1-3, Pavia, Italy, 2017.

5. Hendry, David R. and Amin M. Abbosh, "Triple-mode ceramic cavity filters with wide spurious-free performance," IEEE Transactions on Microwave Theory and Techniques, Vol. 65, No. 10, 3780-3788, 2017.

6. Hendry, David R. and Amin M. Abbosh, "Compact high-isolation base-station duplexer using triple-mode ceramic cavities," IEEE Transactions on Industrial Electronics, Vol. 65, No. 10, 8092-8100, 2018.

7. Hendry, David R. and A. M. Abbosh, "Compact triple-mode bandstop ceramic cavity filters using parallel coupled resonators," IEEE Microwave and Wireless Components Letters, Vol. 29, No. 8, 526-528, IEEE 2019.

8. Fiedziuszko, S. Jerry, Ian C. Hunter, Tatsuo Itoh, Yoshio Kobayashi, Toshio Nishikawa, Steven N. Stitzer, and Kikuo Wakino, "Dielectric materials, devices, and circuits," IEEE Transactions on Microwave Theory and Techniques, Vol. 50, No. 3, 706-720, Mar. 2002.

9. He, Yi, "Research on high performance ceramic dielectric filter," University of Electronic Science and Technology of China, Sichuan, China, 2022.

10. Levy, Ralph, "Direct synthesis of cascaded quadruplet (CQ) filters," IEEE Transactions on Microwave Theory and Techniques, Vol. 43, No. 12, 2940-2945, 1995.

11. Liang, Fei, Shunliang Meng, and Wenzhong Lyu, "Design of microwave ceramic waveguide filter with high out-of-band suppression characteristics," Journal on Communications, Vol. 42, No. 04, 194-201, 2021.

12. Meng, Shunliang, Fei Liang, Zihang Lin, Wenzhong Lu, and Xiaochuan Wang, "Design of six-cavity ceramic waveguide filter with four transmission zeros," 2021 IEEE 4th International Conference on Electronic Information and Communication Technology (ICEICT), 304-307, Xi'an, China, 2021.

13. Meng, Shunliang, Fei Liang, Wenzhong Lu, Zihang Lin, Yuhao Yin, and Rong Zhang, "Design of a microwave filter based on a novel negative coupling structure with conical through-hole," China Communications, Vol. 19, No. 2, 148-157, Feb. 2022.

14. Chen, Yuliang and Ke-Li Wu, "An all-metal capacitive coupling structure for coaxial cavity filters," 2020 IEEE/MTT-S International Microwave Symposium (IMS), 583-586, Los Angeles, CA, USA, 2020.

15. Latif, Muhammad, Giuseppe Macchiarella, and Farooq Mukhtar, "A novel coupling structure for inline realization of cross-coupled rectangular waveguide filters," IEEE Access, Vol. 8, 107527-107538, 2020.

16. Bengui, Y., "Dielectric filter, transceiver, and base station," US Patent App. 16/899, 027, 2020.

17. Hu, Hai and Ke-Li Wu, "A TM11 dual-mode dielectric resonator filter with planar coupling configuration," IEEE Transactions on Microwave Theory and Techniques, Vol. 61, No. 1, 131-138, 2012.

18. Wei, B. and R. Feng Shun, "Dielectric filter,", CN209434356U, Dec. 2019.

19. Du, Zhengjun, Jin Pan, Xinyang Ji, Deqiang Yang, and Xianfeng Liu, "Ceramic dielectric-filled cavity filter," 2020 IEEE 5th Information Technology and Mechatronics Engineering Conference (ITOEC), 888-891, Chongqing, China, 2020.

20. Ansys, Available: www.ansys.com.

21. CST Studio Suite, Available: www.cst.com.

22. Mao, Dong Xing, "Design of dielectric waveguide filter for 5G applications," Nanjing University of Posts and Telecommunications of China, Nanjing, China, 2021.

23. Zhang, Simo, "Design and research of cross-coupled dielectric waveguide filter for 5G applications," Nanjing University of Posts and Telecommunications of China, Nanjing, China, 2023.

Dr. Yang Gao

Professor Yun Xiu Wang

Mr. Xiao Tao Yao

Dr. Guangyong Wei

Dr. Jie Liu