This paper introduces a planar μ-negative (MNG) metamaterial structure, called double-sided split ring resonator (DSRR), which combines the features of a conventional SRR and a broadside-coupled SRR (BC-SRR) to obtain much better miniaturization at microwave frequencies for a given physical cell size. In this study, electromagnetic transmission characteristics of DSRR, BC-SRR and conventional SRR are investigated in a comparative manner for varying values of substrate parameters which are thickness, the real part of relative permittivity and dielectric loss tangent. Simulation results have shown that magnetic resonance patterns of all these three structures are affected in a similar way from variations in permittivity and in loss tangent. However, changes in substrate thickness affect their resonance characteristics quite differently: In response to decreasing substrate thickness, resonance frequency of the SRR increases slowly while the bandwidth and the depth of its resonance curve do not change much. For the DSRR and BCSRR structures, on the other hand, resonance frequency, half power bandwidth and the depth of resonance curve strongly decrease with decreasing substrate thickness. Among these three structures, all having the same unit cell dimensions, the newly suggested DSRR is found to reach the lowest resonance frequency, hence the smallest electrical size, which is a highly desired property not only for more effective medium approximation but also for miniaturization in RF design. The BC-SRR, on the other hand, provides the largest resonance bandwidth which is almost three times of the resonance bandwidth of the SRR. The bandwidth of the DSRR approaches to that of the BC-SRR as the planar separation between its inner and outer rings increases.
2. Pendry, J. B., A. J. Holden, D. J. Robbins, and W. J. Steward, "Low frequency plasmons in thin-wire structures," J. Phys.: Condens. Matter, Vol. 10, 4785-4809, 1998.
3. Pendry, J. B., A. J. Holden, D. J. Robbins, and W. J. Stewart, "Magnetism from conductors and enhanced nonlinear phenomena," IEEE Trans. Microwave Theory Tech., Vol. 47, No. 11, 2075-2084, 1999.
4. Smith, D. R., W. J. Padilla, D. C. Vier, S. C. Nemat-Nasser, and S. Schultz, "Composite medium with simultaneously negative permeability and permittivity," Phys. Rev. Lett., Vol. 84, No. 18, 4184-4187, 2000.
5. Weiland, T., R. Schuhmann, R. B. Greegor, C. G. Parazzoli, A. M. Vetter, D. R. Smith, D. C. Vier, and S. Schultz, "Ab initio numerical simulation of left-handed metamaterials: Comparison of calculation and experiments," J. Appl. Phys., Vol. 90, No. 10, 5419-5424, 2001.
6. Aydin, K., I. Bulu, K. Guven, M. Kafesaki, C. M. Soukoulis, and E. Ozbay, "Investigation of magnetic resonances for different split-ring resonator parameters," New Journalof Physics, Vol. 7, No. 168, 1-15, 2005.
7. Sheng, Z. and V. V. Varadan, "Tuning the effective properties of metamaterials by changing the substrate properties," J. Appl. Phys., Vol. 101, 014909 (1)-(7), 2007.
8. Baena, J. D., R. Marques, F. Medina, and J. Martel, "Artificial magnetic metamaterial design by using spiral resonators," Phys. Rev. B, Vol. 69, 014402 (1)-(5), 2004.
9. Chen, H., L. Ran, J. Huangfu, T. M. Grzegorczyk, and J. A. Kong, "Equivalent circuit model for left-handed metamaterials," J. Appl. Phys., Vol. 100, 024915 (1)-024915 (6), 2006.
10. Bilotti, F., A. Toscano, L. Vegni, K. Aydin, K. B. Alici, and E. Ozbay, "Equivalent-circuit models for the design of metamaterials based on artificial magnetic inclusions," IEEE Trans. Microwave Theory Tech., Vol. 55, No. 12, 2865-2873, 2007.
11. Marques, R., F. Medina, and R. Rafii-El-Idrissi, "Role of bianisotropy in negative permeability and left-handed metamaterials," Phys. Rev. B, Vol. 65, 14440(1)-14440(6), 2002.
12. 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 Trans. Antennas Propag., Vol. 51, No. 10, 2572-2581, 2003.
13. Ghodgaonkar, D. K., V. V. Varadan, and V. K. Varadan, "Free-space measurement of complex permittivity and complex permeability of magnetic materials at microwave frequencies," IEEE Trans. Instrum. Meas., Vol. 39, No. 2, 387-394, 1990.
14. Baena, J. D., J. Bonache, F. Martın, R. M. Sillero, F. Falcone, T. Lopetgi, M. A. G. Laso, J. Garcıa-Garcıa, I. Gil, M. F. Portillo, and M. So, "Equivalent-circuit models for split-ring resonators and complementary split-ring resonators coupled to planar transmission lines," IEEE Trans. Microwave Theory Tech., Vol. 53, No. 4, 1451-1461, 2005.
15. Ekmekci, E. and G. Turhan-Sayan, "Sensitivity of the resonance characteristics of SRR and DSRR (double-sided SRR) type metamaterials to the changes in substrate parameters and the usefulness of DSRR structure for reduced electrical size," PIERS Proceedings, 598-602, 2008.
16. Zhao, H. and T. J. Cui, "A double-spiral resonator structure to realize left-handed material with lower resonant frequency," Microw. Opt. Tecnol. Lett., Vol. 48, No. 5, 923-926, 2006.
17. Alici, K. B., F. Bilotti, L. Vegni, and E. Ozbay, "Miniaturized negative permeability materials," Appl. Phys. Lett., Vol. 91, 071121(1)-(3), 2007.
18. Wu, B., B. Li, T. Su, and C.-H. Liang, "Equivalent-circuit analysis and lowpass filter design of split-ring resonator DGS," Journal of Electromagnetic Waves and Applications, Vol. 20, No. 14, 1943-1953, 2006.
19. Yao, H.-Y., L.-W. Li, Q. Wu, and J. A. Kong, "Macroscopic performance analysis of metamaterials synthesized from microscopic 2-D isotropic cross split-ring resonator array," Progress In Electromagnetics Research, Vol. 51, 197-217, 2005.
20. Cui, T. J., H. F. Ma, R. Liu, B. Zhao, Q. Cheng, and J. Y. Chin, "A symmetrical circuit model describing all kinds of circuit metamaterials," Progress In Electromagnetics Research B, Vol. 5, 63-76, 2008.
21. Aznar, F., M. Gil, J. Bonache, J. Garcıa-Garca, and F. Martin, "Metamaterial transmission lines based on broad-side coupled spiral resonators," Electron. Lett., Vol. 43, No. 9, 2007.
22. Aznar, F., J. Garcıa-Garca, M. Gil, J. Bonache, and F. Martin, "Strategies for the miniaturization of metamaterial resonators," Microw. Opt. Technol. Lett., Vol. 50, No. 5, 1263-1270, 2008.
23. Ziolkowski, R. W., "Design, fabrication, and testing of double negative metamaterials," IEEE Trans. Antennas Propag., Vol. 51, No. 7, 2003.
24. Wu, B.-I., W. Wang, J. Pacheco, X. Chen, T. Grzegorczyk, and J. A. Kong, "A study of using metamaterials as antenna substrate to enhance gain," Progress In Electromagnetics Research, Vol. 51, 295-328, 2005.
25. Ekmekci, E. and G. Turhan-Sayan, "Reducing the electrical size of magnetic metamaterial resonators by geometrical modifications: A comparative study for single-sided and double-sided multiple SRR, spiral and U-spiral resonators," IEEE AP-S International Symposium on Antennas and Propagation, 2008.