This paper presents the design and practical implementation of a wideband spring textile (WST) antenna for wearable communications. The antenna is designed on a felt substrate having a compact dimension of 32 × 42 × 3 mm3 (0.38λg × 0.5λg × 0.036λg). This antenna operates in the 3.14 to 5.45 GHz frequency range, has a bandwidth (BW) of around 2306 MHz, and has a peak realized gain of 6 dBi at 3.5 GHz. Due to a broad frequency coverage, this antenna can be used in a wide range of wireless applications, including 5G and IoT. The proposed design is analyzed in terms of reflection coefficient, radiation pattern, efficiency, gain, and surface current. Using the same electromagnetic simulation software, both characteristic mode analysis (CMA) and the method of moments (MoM) are applied in the design process. The simulated results on a human chest phantom demonstrate the -10-dB impedance bandwidths of 1461 MHz. The antenna prototype is fabricated for verification, and the simulated and measured results demonstrate that the proposed antenna is suitable for wideband on-body applications given its low-profile implementation and mechanical flexibility.
2. Martinez, I., et al., "Compact, low-profile and robust textile antennas with improved bandwidth for easy garment integration," IEEE Access, Vol. 8, 77490-77500, 2020, doi: 10.1109/ACCESS.2020.2989260.
3. Mashaghba, H. A., et al., "Bending assessment of dual-band split ring-shaped and bar slotted all-textile antenna for off-body WBAN/WLAN and 5G applications," 2020 2nd International Conference on Broadband Communications, Wireless Sensors and Powering (BCWSP), 1-5, 2020, doi: 10.1109/BCWSP50066.2020.9249403.
4. Német, A., S. Alkaraki, Q. H. Abassi, and S. F. Jilani, "A biodegradable textile-based graphene antenna for 5G wearable applications," 2021 IEEE International Symposium on Antennas and Propagation and USNC-URSI Radio Science Meeting (APS/URSI), 1583-1584, 2021, doi: 10.1109/APS/URSI47566.2021.9704120.
5. Biçer, M. B. and E. A. Aydin, "Design and fabrication of rectangular microstrip antenna with various flexible substrates," 2021 International Conference on Innovation and Intelligence for Informatics, Computing, and Technologies (3ICT), 360-364, 2021, doi: 10.1109/3ICT53449.2021.9581451.
6. Jalil, M. E. B., M. K. Abd Rahim, N. A. Samsuri, N. A. Murad, H. A. Majid, K. Kamardin, and M. A. Abdullah, "Fractal Koch multiband textile antenna performance with bending, wet conditions and on the human body," Progress In Electromagnetics Research, Vol. 140, 633-652, 2013.
7. Garbacz, R. and R. Turpin, "A generalized expansion for radiated and scattered fields," IEEE Transactions on Antennas and Propagation, Vol. 19, No. 3, 348-358, May 1971, doi: 10.1109/TAP.1971.1139935.
8. Harrington, R. and J. Mautz, "Theory of characteristic modes for conducting bodies," IEEE Transactions on Antennas and Propagation, Vol. 19, No. 5, 622-628, Sep. 1971, doi: 10.1109/TAP.1971.1139999.
9. Harrington, R. and J. Mautz, "Computation of characteristic modes for conducting bodies," IEEE Transactions on Antennas and Propagation, Vol. 19, No. 5, 629-639, Sep. 1971, doi: 10.1109/TAP.1971.1139990.
10. Bauer, J. E. and P. K. Gentner, "Characteristic mode analysis of a circular polarised rectangular patch antenna," Proc. 13th Eur. Conf. Antennas Propag. (EuCAP), 1-3, Krakow, Poland, Apr. 2019.
11. Elias, B. B. Q., P. J. Soh, A. A. Al-Hadi, and P. Akkaraekthalin, "Gain optimization of low-profile textile antennas using CMA and active mode subtraction method," IEEE Access, Vol. 9, 23691-23704, 2021, doi: 10.1109/ACCESS.2021.3056905.
12. Lamsalli, M., A. El Hamichi, M. Boussouis, N. A. Touhami, and T. Elhamadi, "Genetic algorithm optimization for microstrip patch antenna miniaturization," Progress In Electromagnetics Research Letters, Vol. 60, 113-120, 2016.
13. Kaschel, H. and C. Ahumada, "Design of rectangular microstrip patch antenna for 2.4 GHz applied a WBAN," 2018 IEEE International Conference on Automation/XXIII Congress of the Chilean Association of Automatic Control (ICA-ACCA), 1-6, 2018, doi: 10.1109/ICA-ACCA.2018.8609703.
14. Miralles, E., C. Andreu, M. Cabedo-Fabrés, M. Ferrando-Bataller, and J. F. Monserrat, "UWB on-body slotted patch antennas for in-body communications," 2017 11th European Conference on Antennas and Propagation (EUCAP), 167-171, 2017, doi: 10.23919/EuCAP.2017.7928598.
15. Gupta, A., A. Kansal, and P. Chawla, "Design of a compact dual-band antenna for on-/off body communication," IETE J. Res., 1-9, 2020.
16. Yang, H., X. Liu, Y. Fan, and L. Xiong, "Dual-band textile antenna with dual circular polarizations using polarization rotation AMC for off-body communications," IEEE Transactions on Antennas and Propagation, 2021, doi: 10.1109/TAP.2021.3138504.
17. Yang, H. and X. Liu, "Screen-printed dual-band and dual-circularly polarized textile antenna for wearable applications," 2021 15th European Conference on Antennas and Propagation (EuCAP), 1-4, 2021, doi: 10.23919/EuCAP51087.2021.9411013.
18. Yang, H. and X. Liu, "Wearable dual-band and dual-polarized textile antenna for on- and off-body communications," IEEE Antennas and Wireless Propagation Letters, Vol. 19, No. 12, 2324-2328, Dec. 2020, doi: 10.1109/LAWP.2020.3032540.
19. Regina, S. and A. Merline, "Flexible leather substrate dual-band wearable antenna with impact analysis on testing under wet condition for human rescue system," Textile Research Journal, Vol. 91, No. 17-18, 1927-1942, 2021, doi:10.1177/00405175211006214.
20. Kumar Naik, K. and D. Gopi, "Flexible CPW-fed split-triangular shaped patch antenna for WiMAX applications," Progress In Electromagnetics Research M, Vol. 70, 157-166, 2018.
21. Zakir Hossain, A. K. M., N. B. Hassim, S. M. Kayser Azam, Md. S. Islam, and M. K. Hasan, "A planar antenna on flexible substrate for future 5G energy harvesting in Malaysia," International Journal of Advanced Computer Science and Applications (IJACSA), Vol. 11, No. 10, 2020, doi.org/10.14569/IJACSA.2020.0111020.