In this paper, a novel ultrathin five-band polarization insensitive Metamaterial Absorber (MA) is proposed. The proposed structure consists of a periodic array of six arrows with two concentric hexagonal rings, having novel hexagonal 2D-bravais lattices on a grounded FR-4 dielectric substrate (εr = 4.25, loss-tangent tanδ = 0.02). The simulated result shows five discrete absorption peaks. The near unity absorption occurs at 2.7, 6.9, 7.3, 13.6 and 16.9 GHz with peak absorptivity of 88.99, 94.45, 87.58, 93.06 and 90.42% respectively. The proposed absorber is ultrathin with thickness of 0.056λ0 corresponding to the highest frequency of absorption. In order to analyze the absorption mechanism of the structure electromagnetic parameters such as effective permittivity (εeff) and effective permeability μeff) are retrieved and plotted. Wave absorption phenomena are explained by comparative tabulation of real and imaginary parts of electromagnetic parameters. Absorption is further explained by the characteristics impedance and surface current distribution. The structure, being a six-fold symmetric, has been found to be polarization-insensitive under normal incidence. For the oblique incidence of waves, it also achieves high values of absorption for both TE and TM polarizations. The proposed absorber is fabricated, and scattering parameters are measured. Simulated and measured results are in close agreement. Performance of the proposed MA is further investigated by calculating Fractional Bandwidth (FBW). This absorber can find its applications in phase imaging, photo-detector, hyper-spectral imaging, micro-bolometer, spectroscopic detection, surveillance radar and other defence applications.
2. Alu, A. and N. Engheta, "Dispersion characteristics of metamaterial cloaking structures," Electromagnetics, Vol. 28, No. 7, 464-475, Sep. 25, 2008.
3. Zhao, Y. J., B. C. Zhou, Z. K. Zhang, R. Zhang, and B. Y. Li, "A compact tunable metamaterial filter based on split-ring resonators," Optoelectronics Letters, Vol. 13, No. 2, 120-122, Mar. 1, 2017.
4. Majid, H. A., M. K. Abd Rahim, and T. Masri, "Microstrip antenna’s gain enhancement using left-handed metamaterial structure," Progress In Electromagnetics Research M, Vol. 8, 235-247, 2009.
5. Landy, N. I., S. Sajuyigbe, J. J. Mock, D. R. Smith, and W. J. Padilla, "Perfect metamaterial absorber," Physical Review Letters, Vol. 100, No. 20, 207402, May 21, 2008.
6. Li, M., H.-L. Yang, X.-W. Hou, Y. Tian, and D.-Y. Hou, "Perfect metamaterial absorber with dual bands," Progress In Electromagnetics Research, Vol. 108, 37-49, 2010.
7. Ramya, S. and I. S. Rao, "Design of polarization-insensitive dual band metamaterial absorber," Progress In Electromagnetics Research M, Vol. 50, 23-31, 2016.
8. Kaur, K. P., T. K. Upadhyaya, and M. Palandoken, "Dual-band polarization-insensitive meta-material inspired microwave absorber for LTE-band applications," Progress In Electromagnetics Research C, Vol. 77, 91-100, 2017.
9. Khusboo, K., N. Mishra, and R. K. Chaudhary, "Wide-angle polarization independent triple band absorber based on metamaterial structure for microwave frequency application," Progress In Electromagnetics Research C, Vol. 76, 119-127, 2017.
10. Zhai, H., C. Zhan, L. Liu, and C. Liang, "A new tunable dual-band metamaterial absorber with wide-angle TE and TM polarization stability," Journal of Electromagnetic Waves and Applications, Vol. 29, No. 6, 774-785, Apr. 13, 2015.
11. Ayop, O. B., M. K. Abd Rahim, N. A. Murad, N. A. Samsuri, and R. Dewan, "Triple band circular ring-shaped metamaterial absorber for X-band applications," Progress In Electromagnetics Research M, Vol. 39, 65-75, 2014.
12. Lu, L., S. Qu, H. Ma, F. Yu, S. Xia, Z. Xu, and P. Bai, "A polarization-independent wide-angle dual directional absorption metamaterial absorber," Progress In Electromagnetics Research M, Vol. 27, 91-201, 2012.
13. Luo, H. and Y. Z. Cheng, "Ultra-thin dual-band polarization-insensitive and wide-angle perfect metamaterial absorber based on a single circular sector resonator structure," Journal of Electronic Materials, Vol. 47, No. 1, 323-328, 2018.
14. Bhattacharyya, S., S. Ghosh, and K. Vaibhav Srivastava, "Triple band polarization-independent metamaterial absorber with bandwidth enhancement at X-band," Journal of Applied Physics, Vol. 114, No. 9, 094514, Sep. 7, 2013.
15. Chaurasiya, D., S. Ghosh, S. Bhattacharyya, and K. V. Srivastava, "An ultrathin quadband polarization-insensitive wide-angle metamaterial absorber," Microwave and Optical Technology Letters, Vol. 57, No. 3, 697-702, Mar. 1, 2015.
16. Zheng, D., Y. Cheng, D. Cheng, Y. Nie, and R. Z. Gong, "Four-band polarization-insensitive metamaterial absorber based on flower-shaped structures," Progress In Electromagnetics Research, Vol. 142, 221-229, 2013.
17. Wang, W., M. Yan, Y. Pang, J. Wang, H. Ma, S. Qua, H. Chen, C. Xu, and M. Feng, "Ultra-thin quadri-band metamaterial absorber based on spiral structure," Applied Physics A, Vol. 118, No. 2, 443-447, Feb. 1, 2015.
18. Mao, Z., S. Liu, B. Bian, B. Wang, B. Ma, L. Chen, and J. Xu, "Multi-band polarization-insensitive metamaterial absorber based on Chinese ancient coin-shaped structures," Journal of Applied Physics, Vol. 115, No. 20, 204505, May 28, 2014.
19. Smith, D. R., D. C. Vier, T. Koschny, and C. M. Soukoulis, "Electromagnetic parameter retrieval from inhomogeneous metamaterials," Physical Review E,, Vol. 71, No. 3, 036617, Mar. 22, 2005.