In this brief, an ultra-vast stopband lowpass filter with miniaturized circuit size for 26th harmonic suppression using poly-resonators and an inclined stepped-impedance transmission line (ISTL) is developed. The poly-resonators such as radial stub resonator and resonator modules constitute the significant part of the filter, and the discontinuity in the inclined angle of the ISTL is balanced by 75% chamfering. The coupling with ISTL has influence over the stopband behavior, and the equivalent circuit for the first transmission zero is analysed. The normalised circuit size is reduced to 16.6%, and additional frequency rejection is achieved using resonator modules RM1 and RM2. The relative stopband width of 185.4% is attained with a 3 dB cut-off frequency of 1.51 GHz. L band communication applications having circuit area limitations can make use of the Poly-resonator ISTL filter for achieving high-frequency noise rejection.
1. Moloudian, G., S. Bahrami, and R. M. Hashmi, "A microstrip lowpass lter with wide tuning range and sharp roll-off response," IEEE Transactions on Circuits and Systems II: Express Briefs, Vol. 67, No. 12, 2953-2957, 2020. doi:10.1109/TCSII.2020.2985206
2. Boutejdar, A., M. Challal, and S. El Hani, "Design of a new broad stop band (BSB) lowpass filter using compensated capacitor and II-H-II DGS resonator for radar applications," Progress In Electromagnetics Research M, Vol. 73, 91-100, 2018. doi:10.2528/PIERM18062605
3. Paul, B. J., S. Mridula, B. Paul, and P. Mohanan, "Metamaterial inspired CPW fed compact low-pass filter," Progress In Electromagnetics Research C, Vol. 57, 173-180, 2015. doi:10.2528/PIERC15032002
4. Rekha, T., P. Abdulla, P. M. Raphika, and P. M. Jasmine, "Compact microstrip lowpass filter with ultra-wide stopband using patch resonators and open stubs," Progress In Electromagnetics Research C, Vol. 72, 15-28, 2017. doi:10.2528/PIERC16110202
5. Li, Z. and S. J. Ho, "Compact microstrip lowpass filter with ultra-wide stopband characteristic using square ring loaded resonators," Progress In Electromagnetics Research Letters, Vol. 90, 1-5, 2020.
6. Karimi, G., A. Lalbakhsh, and H. Siahkamari, "Design of sharp roll-off lowpass filter with ultra-wide stopband," IEEE Microwave and Wireless Components Letters, Vol. 23, No. 6, 303-305, 2013. doi:10.1109/LMWC.2013.2261057
7. Nouri, L., S. Yahya, and A. Rezaei, "Design and fabrication of a low-loss microstrip lowpass-bandpass diplexer for WiMAX applications," China Communications, Vol. 17, No. 6, 109-120, 2020. doi:10.23919/JCC.2020.06.009
8. Deng, P. H., J. T. Tsai, and R. C. Liu, "Design of a switchable microstrip dual-band lowpass-bandpass filter," IEEE Microwave and Wireless Components Letters, Vol. 24, No. 9, 599-601, 2014. doi:10.1109/LMWC.2014.2332038
9. Choudhary, D. K. and R. K. Chaudhary, "Compact lowpass and dual-band bandpass filter with controllable transmission zero/center frequencies/passband bandwidth," IEEE Transactions on Circuits and Systems II: Express Briefs, Vol. 67, No. 6, 1044-1048, 2019. doi:10.1109/TCSII.2019.2931446
10. Chau, W. M., K. W. Hsu, and W. H. Tu, "Filter-based Wilkinson power divider," IEEE Microwave and Wireless Components Letters, Vol. 24, No. 4, 239-241, 2014. doi:10.1109/LMWC.2014.2299543
11. Jamshidi, M. B., A. Lalbakhsh, B. Mohamadzade, H. Siahkamari, and S. M. H. Mousavi, "A novel neural-based approach for design of microstrip filters," AEU - International Journal of Electronics and Communications, Vol. 110, 152847, 2019. doi:10.1016/j.aeue.2019.152847
12. Fan, M., K. Song, and Y. Fan, "Reconfigurable low-pass filter with sharp roll-off and wide tuning range," IEEE Microwave and Wireless Components Letters, Vol. 30, No. 7, 649-652, 2020. doi:10.1109/LMWC.2020.2997099
13. Xiao, M., G. Sun, and X. Li, "A lowpass filter with compact size and sharp roll-off," IEEE Microwave and Wireless Components Letters, Vol. 25, No. 12, 790-792, 2015. doi:10.1109/LMWC.2015.2496801
14. Rekha, T. K., P. Abdulla, P. M. Jasmine, and A. R. Anu, "Compact microstrip lowpass filter with high harmonics suppression using defected structures," AEU - International Journal of Electronics and Communications, Vol. 115, 153032, 2020. doi:10.1016/j.aeue.2019.153032
15. Lalbakhsh, A., M. B. Jamshidi, H. Siahkamari, A. Ghaderi, A. Golestanifar, R. Linhart, J. Talla, R. B. Simorangkir, and K. Mandal, "A compact lowpass filter for satellite communication systems based on transfer function analysis," AEU - International Journal of Electronics and Communications, Vol. 124, 153318, 2020. doi:10.1016/j.aeue.2020.153318
16. Maramis, H. J. and K. C. Gupta, "Planar analysis and optimization of microstrip discontinuities,", 1988.