In this paper, the inter-digital capacitance loaded loop resonators (IDCLLRs) are proposed to design microstrip band-reject filters. The analyzed structures are based on the coupling of IDCLLRs to a conventional 50 Ω microstrip transmission line. We have firstly studied the frequency response of one-stage IDCLLR-loaded microstrip transmission line. The main fratures of the IDCLLRs are small dimensions (much smaller than the wavelength at resonance) and more structural parameters (provide flexibility in design); Then a 6-stage IDCLLR-based microstip band-reject filter was designed and fabricated, it performs relative rejection bandwidth of 8.1% and rejection level of 23 dB. This stop-band is resulted from presence of the artificial medium with negative effective permeability (μeff<0). In addition, it is easy to control the rejection bandwidth by only employing different length of inter-digital fingers (for multiple tuning). A 9-stage band-reject filter with multiple tuned IDCLLRs has been fabricated and tested, its relative rejection bandwidth is extended to 11.5%. Simulated and measured results are presented.
2. Marques, R., F. Mesa, J. Martel, and F. Medina, "Comparative analysis of edge- and broadside-coupled split ring resonators for metamaterial design---Theory and experiments," IEEE Transactions on Antennas and Propagation, Vol. 51, No. 10, 2572-2581, 2003.
doi:10.1109/TAP.2003.817562
3. Baena, J. D., J. Bonache, F. Martin, R. Marques Sillero, F. Falcone, T. Lopetegi, M. A. G. Laso, J. Garcia-Garcia, I. Gil, M. F. Portillo, and M. Sorolla, "Equivalent-circuit models for split-ring resonators and complementary split-ring resonators coupled to planar ransmission lines," IEEE Trans. Microw. Theory Tech., Vol. 53, No. 4, 1451-1461, Apr. 2005.
doi:10.1109/TMTT.2005.845211
4. Garcia-Garcia, J., J. Bonache, I. Gil, F. Martin, R. Marques, F. Falcone, T. Lopetegi, M. A. G. Laso, and M. Sorolla, "Comparison of electromagnetic band gap and split-ring resonator microstrip lines as stop band structures," Microwave and Optical Tech. Lett., Vol. 44, No. 4, 376-379, Feb. 20, 2005.
doi:10.1002/mop.20640
5. Garcia-Garcia, J., F. Maretin, F. Falcone, J. Bonache, J. D. Baena, I. Gil, E. Amat, T. Lopetigi, M. A. G. Laso, M. A. M. Iturmendi, M. Sorolla, and R. Maraques, "Microwave filters with improved stopband based on sub-wavelength resonators," IEEE Trans. Microw. Theory Tech., Vol. 53, No. 6, 1997-2006, Jun. 2005.
doi:10.1109/TMTT.2005.848828
6. Oznazı, V. and V. B. Erturk, "A comparative investigation of srr- and csrr-based band reject filters: Simulations, experiments, and discussions," Microwave and Optical Tech. Lett., Vol. 50, No. 2, 519-523, Feb. 2008.
doi:10.1002/mop.23119
7. Falcone, F., F. Martin, J. Bonache, R. Marques, and M. Sorolla, "Coplanar waveguide structures loaded with split ring resonators," Microwave and Optical. Tech. Lett., Vol. 40, 3-6, Jan. 2004.
doi:10.1002/mop.11269
8. Martin, F., F. Falcone, J. Bonache, R. Marques, and M. Sorolla, "Miniaturized coplanar waveguide stopband filters based on multiple tuned split ring resonators," IEEE Microw. Wireless Compon. Lett., Vol. 13, No. 12, 511-513, Dec. 2003.
doi:10.1109/LMWC.2003.819964
9. Jelinek, L., J. Machac, and J. Zehentner, "A magnetic metamaterial composed of randomly oriented SRRs," PIERS Online, Vol. 2, No. 6, 624-627, 2006.
doi:10.2529/PIERS060831080303
10. Erentok, A., P. L. Luljak, and R. W. Ziolkowski, "Characterization of a volumetric metamaterial realization of an artificial magnetic conductor for antenna applications," IEEE Transactions on Antennas and Propagation, Vol. 53, No. 1, 160-172, Jan. 2005.
doi:10.1109/TAP.2004.840534
11. Schurig, D., J. J. Mock, B. J. Justice, S. A. Cummer, J. B. Pendry, A. F. Starr, and D. R. Smith, "Metamaterial electromagnetic cloak at microwave frequencies," Science, Vol. 314, 977-980, Nov. 10, 2006.
doi:10.1126/science.1133628
12. Cheng, X. X., et al., "A bianisotropic left-handed metamaterials compose of S-ring resonator," PIERS Online, Vol. 3, No. 3, 241-245, 2007.
doi:10.2529/PIERS061126211441
13. Khan, S. N., Q. L. Zhang, and S. He, "Left handed microstrip transmission line loaded with combination of split ring resonator and complementary-SRR," Journal of Electromagnetic Waves and Applications, Vol. 22, No. 13, 1857-1863, 2008.
doi:10.1163/156939308786375109
14. Xiao, G., J. Mao, and B. Yuan, An artificial magnetic material with interdigital structure, Proc. IEEE AP-S Int. Symp. Dig., Vol. 1, 2558-2561, Hawaii, USA, Jun. 10--15, 2007.
15. Alley, G. D., "Interdigital capacitors and their application to lumped-element microwave integrated circuits," IEEE Trans. Microw. Theory Tech., Vol. 18, No. 12, 1028-1033, 1970.
doi:10.1109/TMTT.1970.1127407
16. Bahl, I. and P. Bhartia, Microwave Solid State Circuit Design, 2nd Ed., Wiley, New York, 2003.
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