volume | PIER Journals

Abstract

This work presents the design and analysis of an ultra-compact multiband circularly polarised microstrip antenna for next-generation implantable medical device (IMD) applications. The antenna is constructed using a Rogers RT/Duroid 3010 substrate, characterised by a relative permittivity (ε_r) of 10.1 and a thickness of 0.635 mm. It features ultra-compact dimensions of 15 × 15 × 0.669 mm³. The design allows for multiband operation at frequencies of 2.5 GHz, 5.8 GHz, 6.8 GHz, and 7.5 GHz. This is done by using U-shaped and rectangular slots, circular perturbations, and a modified ground structure. This configuration ensures a reflection coefficient that remains below -10 dB across both the ISM and UWB-H bands. The proposed design achieves a size reduction of approximately 25-40% compared to existing implantable antennas, while accommodating four operating bands, in contrast to conventional single- or dual-band designs. It provides enhanced bandwidth up to 9.54% in the UWB-H region. Circular polarisation is realised at higher frequencies (7.4-7.6 GHz) with an axial ratio below 3 dB, ensuring orientation-independent communication. The gain ranges from -32.2 dB to -23 dB, consistent with implantable antenna performance in lossy tissues. Performance is validated through full-wave simulations and experimental testing using a three-layer (skin-fat-muscle) tissue model. The maximum specific absorption rate (SAR) is 1.489 W/kg, averaged over 1 gram of tissue, at an input power of 1 W, adhering to IEEE safety standards. Overall, this design successfully balances miniaturisation, multiband operation, polarisation performance, and safety, thereby making it suitable for dependable biomedical telemetry applications.

1. Qamar, Muhammad, Kamil Yavuz Kapusuz, Lawrence Carslake, Tian-Hong Loh, Mohamed A. Thaha, and Akram Alomainy, "Ultra-compact camera-integrated deep-implanted two-port mimo antenna for high-data-rate wireless capsule endoscopy," IEEE Journal of Electromagnetics, RF and Microwaves in Medicine and Biology, Vol. 9, No. 3, 293-301, 2025.
doi:10.1109/jerm.2024.3501385 Google Scholar

2. Basir, Abdul, Youngdae Cho, Izaz Ali Shah, Shahzeb Hayat, Sana Ullah, Muhammad Zada, Syed Ahson Ali Shah, and Hyoungsuk Yoo, "Implantable and ingestible antenna systems: From imagination to realization [bioelectromagnetics]," IEEE Antennas and Propagation Magazine, Vol. 65, No. 5, 70-83, 2023.
doi:10.1109/map.2023.3301398 Google Scholar

3. Sundaravadivel, Palaniselvan, Sathiyapriya Thangavel, Gold Beulah Patturose Jegajothi, Rethinasamy Meenakshi, Dhanushkodi Siva Sundhara Raja, and D. Rajesh Kumar, "A high-performance, thin, circularly polarized microstrip antenna for compact radar systems," Progress In Electromagnetics Research Letters, Vol. 124, 31-36, 2025.
doi:10.2528/pierl24111202 Google Scholar

4. Singh, Dhawan, Neeru Kashyap, and Aditi Thakur, "Design and optimization of a hexagonal-slotted wideband microstrip antenna for 5 G networks RF energy harvesting," Franklin Open, Vol. 13, 100409, 2025.
doi:10.1016/j.fraope.2025.100409 Google Scholar

5. Sharma, Manish, Prabhakara Rao Kapula, Shailaja Salagrama, Kanhaiya Sharma, Ganga Prasad Pandey, Dinesh Kumar Singh, Milind Mahajan, and Anupma Gupta, "Miniaturized quad-port conformal multi-band (QPC-MB) MIMO antenna for on-body wireless systems in microwave-millimeter bands," IEEE Access, Vol. 11, 105982-105999, 2023.
doi:10.1109/access.2023.3318313 Google Scholar

6. Al-Tumah, Wa'il A. Godaymi, Raed M. Shaaban, and Alistair P. Duffy, "Design, simulation, and fabrication of a double annular ring microstrip antenna based on gaps with multiband feature," Engineering Science and Technology, an International Journal, Vol. 29, 101033, 2022.
doi:10.1016/j.jestch.2021.06.013 Google Scholar

7. Rahman, Abdullah Al Mahfazur, Mohammad Tariqul Islam, Md. Moniruzzaman, Sharul Kamal Abdul Rahim, Mandeep Singh, Norbahiah Misran, Md. Shabiul Islam, and Mohamed S. Soliman, "H-shaped modifiers loaded mirror symmetric resonator based double negative metamaterial for multi-band wireless communications," Scientific Reports, Vol. 13, No. 1, 15943, 2023.
doi:10.1038/s41598-023-43182-y Google Scholar

8. Asgharivaskasi, Reza, Valiollah Mashayekhi, Nima Azadi-Tinat, and Mohsen Koohestani, "Ultra-compact quad-band half-mode SIW bandpass filter for Sub-6 GHz 5G applications," Scientific Reports, Vol. 15, No. 1, 30077, 2025.
doi:10.1038/s41598-025-14222-6 Google Scholar

9. Neamah, Watheq A., Haider M. Al Sabbagh, and Hussain Al-Rizzo, "A compact two-element linearly and orthogonal circularly polarized MIMO antenna system for 5G cellular and WLAN/Wi-Fi 6E application," IEEE Access, Vol. 11, 96879-96891, 2023.
doi:10.1109/access.2023.3312122 Google Scholar

10. Patel, Devendra H. and Gautam D. Makwana, "Multiband antenna for 2G/3G/4G and sub-6 GHz 5G applications using characteristic mode analysis," Progress In Electromagnetics Research M, Vol. 115, 107-117, 2023.
doi:10.2528/pierm22122901 Google Scholar

11. Sharma, Manish, Kanhaiya Sharma, Prabhakara Rao Kapula, Anand Nayyar, and Muhammad Bilal, "Dual-Wide Multi-Band (DWMB) four-port flexible MIMO antenna for on-body multiple wireless applications including high diversity performance," PLoS ONE, Vol. 19, No. 11, e0309690, 2024.
doi:10.1371/journal.pone.0309690 Google Scholar

12. Song, Zhiwei, Duming Yang, Yuchao Wang, Youwei Shi, Xianren Zheng, and Lu Wang, "A compact circularly polarized ultra-wide bandwidth implantable antenna for multiple scenarios," Scientific Reports, Vol. 16, 3139, Jan. 2026.
doi:10.1038/s41598-025-32944-5 Google Scholar

13. Himavanth, Nadella, Mohammad Arshad, Shanmugam Kumaravel, Rajesh Natarajan, Avinash Chandra, and Madurakavi Karthikeyan, "Compact circle-shaped circularly polarized implantable antenna with combined e and hexagonal shaped patch for wireless biotelemetry," Results in Engineering, Vol. 27, 105758, 2025.
doi:10.1016/j.rineng.2025.105758 Google Scholar

14. Yin, Bo, Ming Ye, Junhao Cong, and Yingzhuo Xu, "A miniaturized dual-band circularly polarized implantable antenna by half-cutting," Progress In Electromagnetics Research M, Vol. 108, 139-149, 2022.
doi:10.2528/pierm21123003 Google Scholar

15. Sharma, Devesh, Ravi Kumar, and Rajesh K. Vishwakarma, "A miniaturized dual-band modified rectangular-shaped antenna for wireless applications," International Journal of Electrical and Electronics Research, Vol. 10, No. 4, 877-880, 2022.
doi:10.37391/ijeer.100421 Google Scholar

16. Altakhaineh, Amjaad T., Saqer S. Alja’afreh, Aser M. Almatarneh, Eqab Almajali, Luae Al-Tarawneh, and Jawad Yousaf, "A quad-band shared-aperture antenna based on dual-mode composite quarter-mode SIW cavity for 5G and 6G with MIMO capability," Electronics, Vol. 12, No. 11, 2480, 2023.
doi:10.3390/electronics12112480 Google Scholar

17. Sharma, Deepti, Binod Kumar Kanaujia, Vikrant Kaim, Raj Mittra, Ravi Kumar Arya, and Ladislau Matekovits, "Design and implementation of compact dual-band conformal antenna for leadless cardiac pacemaker system," Scientific Reports, Vol. 12, No. 1, 3165, 2022.
doi:10.1038/s41598-022-06904-2 Google Scholar

18. Dayo, Z. A., Q. Cao, Y. Wang, P. Soothar, I. A. Khoso, G. Shah, and M. Aamir, "A compact high gain multiband bowtie slot antenna with miniaturized triangular shaped metallic ground plane," Applied Computational Electromagnetics Society, Vol. 36, No. 7, 935-945, 2021.
doi:10.47037/2021.aces.j.360717 Google Scholar

19. Hu, Xin-yu, Wen-lu Yin, Fen Du, Chao Zhang, Pei Xiao, and Gaosheng Li, "Biomedical applications and challenges of in-body implantable antenna for implantable medical devices: A review," AEU --- International Journal of Electronics and Communications, Vol. 174, 155053, 2024.
doi:10.1016/j.aeue.2023.155053 Google Scholar

20. Green, Ryan B., Mary V. Smith, and Erdem Topsakal, "In vitro and in vivo testing of implantable antennas," Antenna and Sensor Technologies in Modern Medical Applications, 145-189, 2021.
doi:10.1002/9781119683285.ch5

21. Gabriel, C., S. Gabriel, and E. Corthout, "The dielectric properties of biological tissues: I. Literature survey," Physics in Medicine & Biology, Vol. 41, No. 11, 2231-2249, 1996.
doi:10.1088/0031-9155/41/11/001 Google Scholar

22. Gabriel, Camelia, Compilation of the dielectric properties of body tissues at RF and microwave frequencies, 1996.
doi:10.21236/ada303903

23. Ganeshwaran, Nithyanandham, Jegadishkumar Kailairajan Jeyaprakash, Mohammed Gulam Nabi Alsath, and Vidhyashree Sathyanarayanan, "Design of a dual-band circular implantable antenna for biomedical applications," IEEE Antennas and Wireless Propagation Letters, Vol. 19, No. 1, 119-123, Jan. 2020.
doi:10.1109/lawp.2019.2955140 Google Scholar

24. Ung, Johnny and Tutku Karacolak, "A dual-band meandered Dipole antenna for medical telemetry applications," Progress In Electromagnetics Research C, Vol. 63, 85-94, 2016.
doi:10.2528/pierc16012603 Google Scholar

25. Salama, Sanaa, Duaa Zyoud, and Ashraf Abuelhaija, "Design of a dual-band planar inverted F-L implantable antenna for biomedical applications," Journal of Physics: Conference Series, Vol. 1711, No. 1, 012002, Kuala Lumpur, Malaysia, 2020.
doi:10.1088/1742-6596/1711/1/012002

26. Salama, Sanaa, D. Zyoud, and A. Abuelhaija, "A compact-size multiple-band planar inverted L-C implantable antenna used for biomedical applications," Micromachines, Vol. 14, No. 5, 1021, May 2023.
doi:10.3390/mi14051021 Google Scholar

27. Rana, Md. Masud, Md. Ariful Islam, and Ibrahim M. Mehedi, "Dual-band implantable antenna loaded with patch slots for wireless biotelemetry systems," Progress In Electromagnetics Research C, Vol. 141, 151-162, 2024.
doi:10.2528/pierc23112003 Google Scholar

28. Bahrami, Siroos, Gholamhosein Moloudian, Seyyed Reza Miri-Rostami, and Toni Björninen, "Compact microstrip antennas with enhanced bandwidth for the implanted and external subsystems of a wireless retinal prosthesi," IEEE Transactions on Antennas and Propagation, Vol. 69, No. 5, 2969-2974, May 2021.
doi:10.1109/tap.2020.3025245 Google Scholar

29. Shahverdi, Kaveh, Soheil Hashemi, Sadaf Sarafan, and Hung Cao, "Triple-band implantable antenna design for biotelemetry applications in MICS/ISM/Wi-Fi/Bluetooth bands," Technologies, Vol. 10, No. 4, 91, Aug. 2022.
doi:10.3390/technologies10040091 Google Scholar

Mr. Vivek Gupta

Dr. Rajeev Kumar