volume | PIER Journals

Abstract

In this paper, a novel compact lowpass-bandpass microstrip diplexer with high isolation is proposed. The proposed structure consists of a lowpass filter section and a bandpass filter section. The lowpass filter section is designed at a cut-off frequency of 2 GHz with sixth order elliptic filtering characteristics. The bandpass filter section is designed at 3.5 GHz by using a meandered dual-mode loop resonator (MDMLR). The MDMLR is coupled to input port by open circuited feeding lines. The lowpass-bandpass diplexer is formed by combining lowpass and bandpass filter sections without using an additional matching circuit. The designed lowpass-bandpass diplexer has been fabricated and measured in a very good agreement with the simulated results. Isolation between the output ports has been measured as better than 40 dB.

1. Capstick, M. H., "Microstrip lowpass-bandpass diplexer topology," Electron. Lett., Vol. 35, No. 22, 1958-1960, Oct. 1999.
doi:10.1049/el:19991303

2. Deng, P. and J. Tsai, "Design of microstrip lowpass-bandpass diplexer," IEEE Microwave and Wireless Components Letters, Vol. 23, No. 7, 332-334, Jul. 2013.
doi:10.1109/LMWC.2013.2262264

3. Deng, P., R. Liu, W. Lin, and W. Lo, "Design of a microstrip low-pass-bandpass diplexer using direct-feed coupled-resonator filter," IEEE Microwave and Wireless Components Letters, Vol. 27, No. 3, 254-256, Mar. 2017.
doi:10.1109/LMWC.2017.2661971

4. Perez-Wences, C., J. Loo-Yau, I. Lavandera-Hernandez, P. Moreno, A. Reynoso, and L. M. Aguilar Lobo, "Compact microstrip lowpass-bandpass diplexer using radial stubs," Microwave and Optical Technology Letters, Vol. 61, No. 2, 485-489, Feb. 2019.
doi:10.1002/mop.31582

5. Rayatzadeh, S. and G. Moloudian, "Design and fabrication of a miniaturized lowpass-bandpass diplexer with wide tuning range and high isolation," Journal of Electromagnetic Waves and Applications, Vol. 33, No. 14, 1874-1889, Jul. 2019.
doi:10.1080/09205071.2019.1649604

6. Heshmati, H. and S. Roshani, "A miniaturized lowpass bandpass diplexer with high isolation," AEU — International Journal of Electronics and Communications, Vol. 87, 87-94, Apr. 2018.
doi:10.1016/j.aeue.2018.02.004

7. Rezaei, A., L. Noori, and M. H. Jamaluddin, "Novel microstrip lowpass-bandpass diplexer with low loss and compact size for wireless applications," AEU — International Journal of Electronics and Communications, Vol. 101, 152-159, Mar. 2019.
doi:10.1016/j.aeue.2019.02.005

8. Hayati, M., A. Rezaei, and L. Noori, "Design of a high-performance lowpass-bandpass diplexer using a novel microstrip structure for GSM and WiMAX applications," IET Circuits, Devices & Systems, Vol. 13, No. 3, 361-367, Apr. 2019.
doi:10.1049/iet-cds.2018.5395

9. Tu, W. and C. Wu, "Design of microstrip low-pass–bandpass multiplexers using distributed coupling technique," IEEE Transactions on Components, Packaging and Manufacturing Technology, Vol. 6, No. 11, 1648-1655, Nov. 2016.
doi:10.1109/TCPMT.2016.2613881

10. Chen, F., J. Qiu, H. Hu, Q. Chu, and M. J. Lancaster, "Design of microstrip lowpass-bandpass triplexer with high isolation," IEEE Microwave and Wireless Components Letters, Vol. 25, No. 12, 805-807, Dec. 2015.
doi:10.1109/LMWC.2015.2496797

11. Hong, J. S. and M. J. Lancaster, Microstrip Filters for Rf/Microwave Applications, Wiley, New York, 2001.

12. Gorur, A., "Description of coupling between degenerate modes of a dual-mode microstrip loop resonator using a novel perturbation arrangement and its dual-mode bandpass filter applications," IEEE Transactions on Microwave Theory and Techniques, Vol. 52, No. 2, 671-677, Feb. 2004.
doi:10.1109/TMTT.2003.822033

13. Yahya, S. I., A. Rezaei, and L. Nouri, "A novel miniaturized microstrip lowpass bandpass diplexer using patch and interdigital cells for wireless networks," AEU — International Journal of Electronics and Communications, Vol. , No. -, Nov. 202, Vol. 126, No. 1434-8411, Nov. 2020.

14. Nouri, L., S. Yahya, and A. Rezaei, "Design and fabrication of a low-loss microstrip lowpassbandpass-diplexer for WiMAX applications," China Communications, Vol. 17, No. 6, 109-120, Jun. 2020.
doi:10.23919/JCC.2020.06.009

15. Sonnet User’s Manual, Version 16, Sonnet Software, North Syracuse, NY, 2016.

Dr. Seda Elden

Dr. Ali Kursad Gorur