An asymmetrical cross-shaped microstrip resonator is proposed. It is analyzed on its characteristic impedance and resonant conditions. A first order triband bandstop filter (BSF) and a second order triband BSF are designed using this resonator. Both filters are simulated on Sonnet Suite software. Simulation results show that both filters generate three stopbands at 2.0, 3.0, and 4.5 GHz. The second order BSF is also fabricated and measured using a microwave network analyzer. Simulation and measurement results on the second order BSF agree well.
2. Singh, K., K. Ngachenchaiah, D. Bhatnagar, and S. Pal, "Wideband, compact microstrip bandstop filter for triband operations," Proceedings of International Conference on Microwave, 96-98, 2008.
3. Xiao, J. K. and W. J. Zhu, "New defected Microstrip structure bandstop filter," Progress In Electromagnetics Research Symposium, Suzhou, China, September 12-16, 2011.
4. Xiao, J. K. and H. F. Huang, "Square patch resonator bandstop filter," IEEE International Conference on Communication Technology, 104-107, 2010.
5. Wang, Z., F. Nasri, and C. W. Park, "Compact tri-band notched UWB bandpass filter based on interdigital hairpin finger structure," WAMICON 2011 Proceedings, 1-4, 2011.
6. Jankovic, N., R. Geschke, and V. Crnojevic-Benjin, "Compact tri-band bandpass and bandstop filters based on Hilbert-Fork resonators," Microwave and Wireless Components Letters, Vol. 23, No. 6, 282-284, 2013.
7. Liu, L., R. Jin, X. Bai, Y. Li, X. Liang, J. Geng, and C. He, "A tri-band bandstop filter with sharp rejection and controllable bandstop frequencies," Proceedings of IEEE International Symposium on Antennas and Propagation & USNC/URSI National Radio Science Meeting, 2543-2544, 2015.
8. Ahmed, H. A., J. K. Ali, A. J. Salim, and N. Hussain, "A compact triple band BSF design based on Minkowski fractal Geometry," 18th Mediterranean Electro-technical Conference (MELECON), 1-5, 2016.
9. Ning, H., J. Wang, Q. Xiong, and L. Mao, "Design of planar and dual and triple narrowband bandstop filters with independently controlled stopbands and improved spurious response," Progress In Electromagnetics Research, Vol. 131, 259-274, 2012.
10. Boutejdar, A. and S. D. Bennani, "Design and fabrication of tri-stopband bandstop filters using cascaded and multi-armed method," Advanced Electromagnetics, Vol. 6, No. 3, 2017.
11. Adhikari, K. K. and N. Y. Kim, "Microstrip triband bandstop filter with sharp stop band skirts and independently controllable second stop band response," The Scientific World Journal, Vol. 2014, Article ID 760838, 9 pages, http://dx.doi.org/10.1155/2014/760838, 2014.
12. Pozar, D. M., Microwave Engineering, 2nd Ed., 65-68, John Wiley & Sons Inc., 1998.