This paper proposes an efficient microstrip isolator filter which suppresses the surface and lateral waves (SW and LW) in planar antenna arrays. The structure consists in a double or triple row of periodic and flipped array of subwavelength Complementary Split Ring Resonators (CSRRs). The array of CSRRs is etched on a dielectric substrate backed by a metallic ground plane. These structures can both block the electromagnetic (EM) energy in one direction and guide it along the other transverse direction. In particular, the flipped array of CSRRs presents wider bandgap characteristic (stopband ≥20%) than periodic array of CSRRs (~16%) and conventional array of SRRs (≥12%). Then, the metamaterial filter is inserted between two 6.1 GHz probe-fed patch antenna elements separated by a distance of 0.8 λ0. Excellent agreements between the simulated and the experimental results are obtained. In fact, a significant reduction of the EM mutual coupling is achieved, more than 24 dB, over a wide frequency bandwidth. Moreover, the proposed CSRR structures are compact, low complex and, as printed antennas, are very easy to manufacture. They have numerous applications in MIMO systems and directive phased arrays.
2. Fu, Y. Q., Q. R. Zheng, Q. Gao, and G. H. Zhang, "Mutual coupling redection between large antenna arrays using electromagnetic bandgap (EBG) structures," Journal of Electromagnetic Waves and Applications, Vol. 120, No. 6, 819-825, 2006.
3. Yang, F. and Y. R. Samii, Electromagnetic Band Gap Structures in Antenna Engineering, Cambridge University Press, 2009.
4. Karnfelt, C., P. Hallbjorner, H. Zirath, and A. Alping, "High gain active microstrip antenna for 60-GHz WLAN/WPAN applications," IEEE Trans. on Microw. Theory and Tech., Vol. 54, No. 6, 2593-2603, Jun. 2006.
5. Ohnimus, F., I. Ndip, E. Engin, S. Guttowski, and H. Reichl, "Study on shielding effectiveness of mushroom-type electromagnetic bandgap structures in close proximity to patch antennas," Proc. LAPC, 737-740, Loughborough, UK, 2009.
6. Nikolic, M., A. Djordjevic, and A. Nehorai, "Microstrip antennas with suppressed radiation in horizontal directions and reduced coupling," IEEE Trans. on Antennas and Propag., Vol. 53, No. 11, 3469-3476, Nov. 2005.
7. Tan, M. N. M., T. A. Rahman, S. K. A. Rahim, M. T. Ali, and M. F. Jamlos, "Antenna array enhancement using mushroom-like electromagnetic band gap (EBG)," Proc. 4th EuCAP, 1-5, Barcelona, Spain, Apr. 2010.
8. Coulombe, M., S. F. Koodiani, and C. Caloz, "Compact elongated mushroom (EM)-EBG structure for enhancement of patch antenna array performances," IEEE Trans. on Antennas and Propag., Vol. 58, No. 4, 1076-1086, Apr. 2010.
9. Yang, F. and Y. R. Samii, "Microstrip antennas integrated with electromagnetic band-gap (EBG) structures: A low mutual coupling design for array applications," IEEE Trans. on Antennas and Propag., Vol. 51, No. 10, 2936-2946, Oct. 2003.
10. Li, L., B. Li, H. X. Liu, and C. H. Liang, "Locally resonant cavity cell model for electromagnetic band gap structures," IEEE Trans. on Antennas and Propag., Vol. 54, No. 10, 90-100, Jan. 2006.
11. Tang, M.-C., S.-Q. Xiao, S.-S. Gao, G. Jian, and B.-Z. Wang, "Mutual coupling suppressing based on a new type electric resonant SRRs in microstrip array," Acta Phys. Sin., Vol. 59, No. 3, 1851-1856, 2010.
12. Tang, M.-C., S.-Q. Xiao, J. Guan, Y.-Y. Bai, S.-S. Gao, and B.-Z.Wang, "Composite metamaterial enabled excellent performance of microstrip antenna array," Chin. Phys. B,, Vol. 19, No. 7, 074214, 2010.
13. Tang, M.-C., S. Q. Xiao, B. Z. Wang, J. Guan, and T. W. Deng, "Improved performance of a microstrip phased array using broadband and ultra-low-loss metamaterial slabs," IEEE Antennas and Propagation Magazine, Vol. 53, No. 6, 31-41, Dec. 2011.
14. Habashi, A., J. Nourinia, and C. Ghobadi, "Mutual coupling reduction between very closely spaced patch antennas using low-profile folded split-ring resonators (FSRRs)," IEEE Antennas and Wireless Propagation Letters, Vol. 10, 862-865, 2011.
15. Bait-Suwailam, M. M., M. S. Boybay, and O. M. Ramahi, "Electromagnetic coupling reduction in high-profile monopole antennas using single-negative magnetic metamaterials for MIMO applications," IEEE Trans. on Antennas and Propag., Vol. 58, No. 9, 2894-2902, Sep. 2010.
16. Falcone, F., T. Lopetegi, J. D. Baena, R. Marques, F. Martin, and M. Sorolla, "Effective negative-epsilon stopband microstrip lines based on complementary split ring resonators ," IEEE Microwave and Wireless Components Letters, Vol. 14, 280-282, 2004.
17. Abdalla, M. A., M. A. Fouad, H. A. Elregeily, and A. A. Mitkees, "Wideband negative permittivity metamaterial for size reduction of stopband filter in antenna applications," Progress In Electromagnetics Research C, Vol. 25, 55-66, 2012.
18. Khan, S. N., X. G. Liu, L. X. Shao, and Y. Wang, "Complementary split ring resonators of large stop bandwidth," Progress In Electromagnetics Research Letters, Vol. 14, 127-132, 2010.
19. Bait-Suwailam, M. M., O. F. Siddiqui, and O. M. Ramahi, "Mutual coupling reduction between microstrip patch antennas using slotted-complementary split-ring resonators ," IEEE Antennas and Wireless Propagation Letters, Vol. 9, 876, 2010.
20. Bait-Suwailam, M. M., O. F. Siddiqui, and O. M. Ramahi, "Artificial complementary resonators for mutual coupling reduction in microstrip antennas ," Proceedings of the 41st European Microwave Conference, EuMA, 10-13, Manchester, UK, Oct. 2011.
21. Lu, H. M., J. X. Zhao, and Z. Y. Yu, "Design and analysis of a novel electromagnetic bandgap structure for suppressing simultaneous switching noise," Progress In Electromagnetics Research C, Vol. 30, 81-91, 2012.
22. Bitzer, A., A. Ortner, H. Merbold, T. Feurer, and M. Walther, "Terahertz near-field microscopy of complementary planar metamaterials: Babinet's principle," Optics Express, Vol. 19, No. 3, 2537, Optical Society of America, OSA, Jan. 31, 2011.
23. Baena, J. D., J. Bonache, F. MartÍn, R. M. Sillero, F. Falcone, T. Lopetegi, M. A. G. Laso, J. G. GarcÍa, I. Gil, M. F. Portillo, and M. Sorol, "Equivalent-circuit models for split-ring resonators and complementary split-ring resonators coupled to planar transmission lines," IEEE Trans. on Microw. Theory and Tech., Vol. 53, No. 4, 1451-1461, Apr. 2005.
24. Tran, C.-M., H. Hafdallah-Ouslimani, L. Zhou, A. C. Priou, H. Teillet, J.-Y. Daden, and A. Ourir, "High impedance surfaces based antennas for high data rate communications at 40 GHz," Progress In Electromagnetic Research C, Vol. 13, 217-299, 2010.
25. Ouslimani, H. H., X. Han, and T. Zhang, "Analysis and reduction of electromagnetic coupling interferences in microstrip antenna arrays," Advanced Electromagnetics Symposium, AES, 16-18, Paris, France, Apr. 2012.
26. , , , http://www.ansys.com/Products/Simulation+Technology/Elect-romagnetics/High-Performance+Electronic+Design/ANSYS+H-FSS.
27. , , , http://www.cst.com/content/products/mws/overview.aspx.
28. , , , RT/duroid 6006/6010 Dada sheet: http://www.rogerscorp.com/documents/612/acm/RT-duroid-6006-6010-laminate-data-sheet.aspx..