In this paper, a miniaturized dual-band circularly polarized (CP) implantable antenna is proposed. The -10 dB impedance bandwidth of the antenna in Industrial Scientific Medical (ISM) band and the low frequency part of UWB can reach 30.3% (2.02~2.74 GHz) and 39.9% (3.73~5.59 GHz), respectively. The important features are its CP characteristic in two bands and a small volume. The miniaturization of the antenna is realized by half-cutting technique, which is to cut the original antenna meeting the symmetry of structure and electric field distribution into two halves to obtain a compact structure and wider impedance bandwidth, so that the final size is 5×10.4×0.254 mm3. The CP wave performance of the antenna is achieved by exciting orthogonal polarization components on the radiation surface. The proposed antenna provides an axial ratio of less than 3 dB. CP axial ratio bandwidths in the two bands are 24.4% and 18.1%, respectively. In addition, the safety considerations and link margin are evaluated to analyze the performance of the proposed antenna. In order to verify the simulation results, the proposed antenna is fabricated. The measurements are carried out under the human muscle mimicking liquid circumstances. The measured data are in good agreement with the simulation results.
2. Saraswat, R. K. and M. Kumar, "Implementation of metamaterial loading to miniaturized UWB dipole antenna for WLAN and WiMAX applications with tunability characteristics," IETE Journal of Research, Vol. 2, 1-14, 2019.
3. 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, e21824, 2019.
4. Saraswat, R. K. and M. Kumar, "Implementation of hybrid fractal metamaterial inspired frequency band reconfigurable multiband antenna for wireless applications," International Journal of RF and Microwave Computer-Aided Engineering, Vol. 30, e22315, 2020.
5. Greatbatch, W. and C. F. Holmes, "History of implantable devices," IEEE Eng. Med. Biol., Vol. 10, No. 3, 38-41, 1991.
6. Islam, M. N. and M. R. Yuce, "Review of medical implant communication system (MICS) band and network," ICT Express, Vol. 2, No. 4, 188-194, 2016.
7. Zada, M., et al., "Ultra-compact implantable antenna with enhanced performance for leadless cardiac pacemaker system," IEEE Trans. Antennas Propag., Vol. 69, No. 2, 1152-1157, 2021.
8. Asif, S. M., et al., "Design and in vivo test of a batteryless and fully wireless implantable asynchronous pacing system," IEEE Transactions on Biomedical Engineering, Vol. 63, No. 5, 1070-1081, 2016.
9. Ahsan, N. K., C. Young-Ok, G. Henry, and H. Yang, "Recent advances in organ specific wireless bioelectronic devices: Perspective on biotelemetry and power transfer using antenna systems," Engineering, 2022.
10. Malik, N. A., P. Sant, T. Ajmal, and M. Ur-Rehman, "Implantable antennas for bio-medical applications," IEEE Journal of Electromagnetics, RF and Microwaves in Medicine and Biology, Vol. 5, No. 1, 84-96, 2021.
11. Singh, M. S., J. Ghosh, S. Ghosh, and A. Sarkhel, "Miniaturized dual-antenna system for implantable biotelemetry application," IEEE Antennas and Wireless Propagation Letters, Vol. 20, No. 8, 1394-1398, 2021.
12. Ghosh, J. and D. Mitra, "Restoration of antenna performance in the vicinity of metallic cylinder in implantable scenario," IET Microwaves Antennas & Propagation, Vol. 14, No. 12, 1440-1445, 2020.
13. Shah, I. A., M. Zada, and H. Yoo, "Design and analysis of a compact-sized multiband spiral-shaped implantable antenna for scalp implantable and leadless pacemaker systems," IEEE Trans. Antennas Propag., Vol. 67, No. 6, 4230-4234, 2019.
14. Soontornpipit, P. and P. Satitvipawee, "Design and development of a dual-band PIFA antenna for wireless biotelemetry applications," 2018 International Electrical Engineering Congress, iEECON, 1-4, 2018.
15. Bao, Z., Y. X. Guo, and R. Mittra, "Single-layer dual-/tri-band inverted-f antennas for conformal capsule type of applications," IEEE Trans. Antennas Propag., Vol. 65, No. 12, 7257-7265, 2017.
16. Faisal, F., et al., "A miniaturized dual-band implantable antenna system for medical applications," IEEE Trans. Antennas Propag., Vol. 68, No. 2, 1161-1165, 2020.
17. Liu, K., et al., "Design of conformal spiral dual-band antenna for wireless capsule system," IEEE Access, Vol. 9, 117349-117357, 2021.
18. Li, R., Y. X. Guo, B. Zhang, and G. Du, "A miniaturized circularly polarized implantable annular-ring antenna," IEEE Antennas and Wireless Propagation Letters, Vol. 16, 2566-2569, 2017.
19. Das, R. and H. Yoo, "A wideband circularly polarized conformal endoscopic antenna system for high-speed data transfer," IEEE Trans. Antennas Propag., Vol. 65, No. 6, 2816-2826, 2017.
20. Hayat, S., S. A. A. Shah, and H. Yoo, "Miniaturized dual-band circularly polarized implantable antenna for capsule endoscopic system," IEEE Trans. Antennas Propag., Vol. 69, No. 4, 1885-1895, 2021.
21. Samanta, G. and D. Mitra, "Dual-band circular polarized flexible implantable antenna using reactive impedance substrate," IEEE Trans. Antennas Propag., Vol. 67, No. 6, 4218-4223, 2019.
22. Duan, Z. and L. J. Xu, Dual-band implantable antenna with circular polarisation property for ingestible capsule application, Vol. 53, No. 16, 1090-1092, Electronics Letters, 2017.
23. Xu, L. J., et al., "Circularly polarized annular ring antenna with wide axial-ratio bandwidth for biomedical applications," IEEE Access, Vol. 7, 59999-60009, 2019.
24. Xu, L. J., et al., "Circularly polarized implantable antenna with improved impedance matching," IEEE Antennas and Wireless Propagation Letters, Vol. 19, No. 5, 876-880, 2020.
25. Mobashsher, A. T. and A. Abbosh, "Utilizing symmetry of planar ultra-wideband antennas for size reduction and enhanced performance," IEEE Antennas and Propagation Magazine, Vol. 57, No. 2, 153-166, 2015.
26. Gabriel, S., R. W. Lau, and C. Gabriel, "The dielectric properties of biological tissues: III. Parametric models for the dielectric spectrum of tissues," Physics in Medicine and Biology, Vol. 41, No. 11, 2271-2293, 1996.
27. Xia, W., K. Saito, M. Takahashi, and K. Ito, "Performances of an implanted cavity slot antenna embedded in the human arm," IEEE Trans. Antennas Propag., Vol. 57, No. 4, 894-899, 2009.