A compact triple-band antenna of size 20×13×1.6 mm3 for WLAN (2.4/5 GHz) and WiMAX (3.5 GHz) applications and a metamaterial slab for Specific Absorption Rate (SAR) reduction are proposed in this paper. The antenna comprises a rectangular patch with two conjoint square split rings, attached along its top edge, to excite two resonances in the 2.5 GHz and 5.5 GHz range. The antenna is also backed with a slotted ground plane structure to achieve miniaturization. The radiator is subsequently slotted to yield the third tone around 3.5 GHz. Several parameters are tuned independently to achieve the desired bands of resonance around (2.2-2.6) GHz, (3.40-3.60) GHz, and (5.0-6.9) GHz with impedance bandwidths of 17%, 5.5%, and 46%, respectively. To validate the simulated results, the designed antenna is fabricated and measured experimentally. Later, a metamaterial slab composed of a 5×3 array of pentagonal split-rings printed on a 20×13×1.6 mm3 FR-4 substrate is placed above the antenna at a suitable distance to increase the gain as well as to reduce the SAR. Inclusion of this slab improved the maximum radiation efficiency and gain of the proposed antenna from 65% and 2.7 dB to 80% and 3 dB. A cubical tissue model is designed and used for simulation. SAR reduction of 84.5% is inferred with the metamaterial slab. This paper has taken a cubical tissue model for SAR calculation, which can be further enhanced by taking a human phantom model in future.
2. Saraswat, R. K. and M. Kumar, "Miniaturized slotted ground UWB antenna loaded with metamaterial for WLAN and WiMAX applications," Progress In Electromagnetics Research, Vol. 65, 65-80, 2016.
3. Li, L., et al., "A compact triple-band printed monopole antenna for WLAN/WiMAX applications," IEEE Antennas and Wireless Propagation Letters, Vol. 15, 1853-1855, 2016.
4. Hoang, T. V., et al., "Quad-band circularly polarized antenna for 2.4/5.3/5.8-GHz WLAN and 3.5-GHz WiMAX applications," IEEE Antennas and Wireless Propagation Letters, Vol. 15, 1032-1035, 2015.
5. Naidu, P. V., A. Malhotra, and R. Kumar, "A compact ACS-fed dual-band monopole antenna for LTE, WLAN/WiMAX and public safety applications," Microsystem Technologies, Vol. 22, No. 5, 1021-1028, 2016.
6. Mathew, S., et al., "Compact dual polarised V slit, stub and slot embedded circular patch antenna for UMTS/WiMAX/WLAN applications," Electronics Letters, Vol. 52, No. 17, 1425-1426, 2016.
7. Kunwar, A., A. K. Gautam, and B. K. Kanaujia, "Inverted L-slot triple-band antenna with defected ground structure for WLAN and WiMAX applications," International Journal of Microwave and Wireless Technologies, Vol. 9, No. 1, 191-196, 2017.
8. Ahmad, H., et al., "Compact triband slotted printed monopole antenna for WLAN and WiMAX applications," International Journal of RF and Microwave Computer-Aided Engineering, 2019.
9. Nelaturi, S. and N. V. S. N. Sarma, "A compact microstrip patch antenna based on metamaterials for Wi-Fi and WiMAX applications," Journal of Electromagnetic Engineering and Science, Vol. 18, No. 3, 182-187, 2018.
10. Ali, T., et al., "A multiband antenna loaded with metamaterial and slots for GPS/WLAN/WiMAX applications," Microwave and Optical Technology Letters, Vol. 60, No. 1, 79-85, 2018.
11. Li, H., et al., "Dual-band planar antenna loaded with CRLH unit cell for WLAN/WiMAX application," IET Microwaves, Antennas & Propagation, Vol. 12, No. 1, 132-136, 2017.
12. Alibakhshikenari, M., et al., "A comprehensive survey of “Metamaterial transmission-line based antennas: Design, challenges, and applications”," IEEE Access, Vol. 8, 144778-144808, 2020.
13. Alibakhshikenari, M., et al., "Super-wide impedance bandwidth planar antenna for microwave and millimeter-wave applications," Sensors, Vol. 19, No. 10, 2306, 2019.
14. Alibakhshi-Kenari, M., M. Naser-Moghadasi, and R. A. Sadeghzadeh, "Bandwidth and radiation specifications enhancement of monopole antennas loaded with split ring resonators," IET Microwaves, Antennas & Propagation, Vol. 9, No. 14, 1487-1496, 2015.
15. Alibakhshi-Kenari, M., M. Naser-Moghadasi, and R. Sadeghzadeh, "The resonating MTM-based miniaturized antennas for wide-band RF-microwave systems," Microwave and Optical Technology Letters, Vol. 57, No. 10, 2339-2344, 2015.
16. Alibakhshi-Kenari, M., et al., "Miniature CRLH-based ultra wideband antenna with gain enhancement for wireless communication applications," ICT Express, Vol. 2, No. 2, 75-79, 2016.
17. Alibakhshikenari, M., et al., "Miniaturised planar-patch antenna based on metamaterial L-shaped unit-cells for broadband portable microwave devices and multiband wireless communication systems," IET Microwaves, Antennas & Propagation, Vol. 12, No. 7, 1080-1086, 2018.
18. Alibakhshikenari, M., B. S. Virdee, and E. Limiti, "Compact single-layer traveling-wave antenna design using metamaterial transmission lines," Radio Science, Vol. 52, No. 12, 1510-1521, 2017.
19. Alibakhshi-Kenari, M., et al., "New CRLH-based planar slotted antennas with helical inductors for wireless communication systems, RF-circuits and microwave devices at UHF-SHF bands," Wireless Personal Communications, Vol. 92, No. 3, 1029-1038, 2017.
20. Alibakhshi-Kenari, M., et al., "Periodic array of complementary artificial magnetic conductor metamaterials-based multiband antennas for broadband wireless transceivers," IET Microwaves, Antennas & Propagation, Vol. 10, No. 15, 1682-1691, 2016.
21. Alibakhshi-Kenari, M., et al., "New compact antenna based on simplified CRLH-TL for UWB wireless communication systems," International Journal of RF and Microwave Computer-Aided Engineering, Vol. 26, No. 3, 217-225, 2016.
22. Alibakhshi-Kenari, M., et al., "Metamaterial-based antennas for integration in UWB transceivers and portable microwave handsets," International Journal of RF and Microwave Computer-Aided Engineering, Vol. 26, No. 1, 88-96, 2016.
23. Sallam, M. O., et al., "Wideband CPW-fed flexible bow-tie slot antenna for WLAN/WiMax systems," IEEE Transactions on Antennas and Propagation, Vol. 65, No. 8, 4274-4277, 2017.
24. Priyadarshini, S. J. and D. J. Hemanth, "Investigation and reduction methods of specific absorption rate for biomedical applications: A survey," International Journal of RF and Microwave Computer- Aided Engineering, Vol. 28, No. 3, e21211, 2018.
25. Stephen, J. P. and D. J. Hemanth, "An investigation on specific absorption rate reduction materials with human tissue cube for biomedical applications," International Journal of RF and Microwave Computer-Aided Engineering, e21960, 2019.
26. Hwang, J.-N. and F.-C. Chen, "Reduction of the peak SAR in the human head with metamaterials," IEEE Transactions on Antennas and Propagation, Vol. 54, No. 12, 3763-3770, 2006.
27. Saraswat, R. K. and M. Kumar, "A metamaterial hepta-band antenna for wireless applications with specific absorption rate reduction," International Journal of RF and Microwave Computer-Aided Engineering, Vol. 29, No. 10, e21824, 2019.
28. Imaculate Rosaline, S. and S. Raghavan, "Design and analysis of a SRR superstrate for SAR reduction," Journal of Electromagnetic Waves and Applications, Vol. 29, No. 17, 2330-2338, 2015.
29. Janapala, D. K., et al., "Specific absorption rate reduction using metasurface unit cell for flexible polydimethylsiloxane antenna for 2.4 GHz wearable applications," International Journal of RF and Microwave Computer-Aided Engineering, Vol. 29, No. 9, e21835, 2019.
30. Gil, I., R. Seager, and R. Fernandez-Garcıa, "Embroidered metamaterial antenna for optimized performance on wearable applications," Physica Status Solidi (A), Vol. 215, No. 21, 1800377, 2018.
31. Nazeri, A., A. Abdolali, and M. Mehdi, "An extremely safe low-SAR antenna with study of its electromagnetic biological effects on human head," Wireless Personal Communications, 1-14, 2019.
32. Ramachandran, T., et al., "Specific absorption rate reduction of multi split square ring metamaterial for L- and S-band application," Results in Physics, 102668, 2019.
33. Chen, H., et al., "Experimental retrieval of the effective parameters of metamaterials based on a waveguide method," Opt. Express., Vol. 14, 12944-12949, 2006, 10.1364/OE.14.012944.
34. Smith, D. R., et al., "Electromagnetic parameter retrieval from inhomogeneous metamaterials," Physical Review E, Vol. 71, No. 3, 036617, 2005.
35. Baena, J. D., J. Bonache, F. Martın, R. Marques, F. Falcone, T. Lopetegi, M. Laso, J. Garcıa- Garcıa, I. Gil, M. Portillo, and M. Sorolla Ayza, "Equivalent-Circuit models for split-ring resonators and complementary split-ring resonators coupled to planar transmission lines," IEEE Transactions on Microwave Theory and Techniques, Vol. 53, 1451-1461, 2005, 10.1109/TMTT.2005.845211.