volume | PIER Journals

Abstract

In this paper, an optimized flexible Microstrip Patch Antenna (MPA) for wearable applications is introduced, particularly characterized by its design concepts of scalable design and comprehensive performance evaluation. The proposed antenna leverages the mechanical flexibility of a leather substrate, complemented by polyimide layers on the upper and lower surfaces of the copper patch, enhancing both structural integrity and electromagnetic performance. The design is optimized for the operation at 2.4\,GHz, ensuring durability and stability even under dynamic bending conditions. Various critical performance metrics, such as resonance frequency, bandwidth, return loss, Voltage Standing Wave Ratio (VSWR), Specific Absorption Rate (SAR) and gain, are evaluated experimentally and through simulation across bending angles of 0-90°. Results also show that the antenna can reliably operate in an extreme bending scenario while having a resonant frequency near 2.44 GHz with a return loss (S₁₁) less than -20 dB up to 60° bending. At approximately 31 MHz bandwidth stability is preserved, and the VSWR is less than 1.2, thus the impedance matching is effective. Further gain measurements are also made under deformation, which further confirms the stable performance and thus reliability of the wearable application. Additionally, SAR analysis is conducted to ensure the antenna's compliance with electromagnetic exposure safety limits. The maximum SAR value of 0.516 W/kg remains well within FCC (1.6 W/kg) and ICNIRP (2.0 W/kg) standards, confirming safe radiation levels. Polyimide shielding improves durability, reduces interference, and minimizes backward radiation, making the design ideal for Wireless Body Area Networks (WBANs) and biomedical monitoring.

1. Soni, Gaurav Kumar, Dinesh Yadav, and Ashok Kumar, "A comprehensive review of wearable antenna design for On-Body and Off-Body communication," International Journal of Electronics and Telecommunications, Vol. 70, No. 2, 525-532, 2024. Google Scholar

2. Thangarasu, Deepa, Rama Rao Thipparaju, Sandeep Kumar Palaniswamy, Malathi Kanagasabai, Mohammed Gulam Nabi Alsath, Devisowjanya Potti, and Sachin Kumar, "On the design and performance analysis of flexible planar monopole ultra-wideband antennas for wearable wireless applications," International Journal of Antennas and Propagation, Vol. 2022, No. 1, 5049173, 2022. Google Scholar

3. Kumar, Anubhav, Asok De, and R. K. Jain, "Circular polarized two-element textile antenna with high isolation and polarization diversity for wearable applications," International Journal of Microwave and Wireless Technologies, Vol. 15, No. 3, 493-501, 2023. Google Scholar

4. Soni, Gaurav Kumar, Dinesh Yadav, and Ashok Kumar, "Design consideration and recent developments in flexible, transparent and wearable antenna technology: A review," Transactions on Emerging Telecommunications Technologies, Vol. 35, No. 1, e4894, 2024. Google Scholar

5. Jilani, Syeda Fizzah, Qammer H. Abbasi, and Akram Alomainy, "Inkjet-printed millimetre-wave PET-based flexible antenna for 5G wireless applications," 2018 IEEE MTT-S International Microwave Workshop Series on 5G Hardware and System Technologies (IMWS-5G), 1-3, Dublin, Ireland, 2018.

6. Kirtania, Sharadindu Gopal, Alan Wesley Elger, Md. Rabiul Hasan, Anna Wisniewska, Karthik Sekhar, Tutku Karacolak, and Praveen Kumar Sekhar, "Flexible antennas: A review," Micromachines, Vol. 11, No. 9, 847, 2020. Google Scholar

7. Prasanna, R., G. Thamarai Selvi, Karuppiah Annaram, K. Venkatalakshmi, M. Jenath, and Banu Priya Prathaban, "Multiband flexible ultra-wideband antenna for wearable electronics and biomedical applications," International Journal for Multiscale Computational Engineering, Vol. 21, No. 5, 93-104, 2023. Google Scholar

8. Venkatachalam, Dinesh, Vijayalakshmi Jagadeesan, Kamal Batcha Mohamed Ismail, Manoharan Arun Kumar, Shanmugam Mahalingam, and Junghwan Kim, "Compact flexible planar antennas for biomedical applications: Insight into materials and systems design," Bioengineering, Vol. 10, No. 10, 1137, 2023. Google Scholar

9. Geyikoglu, Miraç Dilruba, "A novel UWB flexible antenna with dual notch bands for wearable biomedical devices," Analog Integrated Circuits and Signal Processing, Vol. 114, No. 3, 439-450, 2023. Google Scholar

10. Varma, Sanjit, Somia Sharma, Merbin John, Richa Bharadwaj, Anuj Dhawan, and Shiban K. Koul, "Design and performance analysis of compact wearable textile antennas for IoT and body‐centric communication applications," International Journal of Antennas and Propagation, Vol. 2021, No. 1, 7698765, 2021. Google Scholar

11. Wang, Mengchu, Lorenzo Crocco, and Marta Cavagnaro, "Antipodal vivaldi antenna with ceramic cone lens for biomedical microwave imaging systems," 2021 15th European Conference on Antennas and Propagation (EuCAP), 1-5, Dusseldorf, Germany, 2021.

12. Aldhaibani, Jaafar A., Mohammed Q. Mohammed, Ali A. Mahmood, and Mohammed Sellab Hamza, "Development of wearable textile patch antenna 2.43 GHz for biomedical applications," International Journal of Advanced Technology and Engineering Exploration, Vol. 11, No. 111, 177, 2024. Google Scholar

13. Mahfuz, M. M. Hasan, Md. Rafiqul Islam, Chan-Wang Park, Elfatih A. A. Elsheikh, F. M. Suliman, Mohamed Hadi Habaebi, Norun Abdul Malek, and Nazmus Sakib, "Wearable textile patch antenna: Challenges and future directions," IEEE Access, Vol. 10, 38406-38427, 2022. Google Scholar

14. Kumar, S. Ashok, T. Shanmuganantham, and G. Sasikala, "Design and development of implantable CPW fed monopole U slot antenna at 2.45 GHz ISM band for biomedical applications," Microwave and Optical Technology Letters, Vol. 57, No. 7, 1604-1608, 2015. Google Scholar

15. Cheng, Shi and Zhigang Wu, "Microfluidic stretchable RF electronics," Lab on a Chip, Vol. 10, No. 23, 3227-3234, 2010. Google Scholar

16. Mu, Guangchen and Pengshan Ren, "A compact dual-band metasurface-based antenna for wearable medical body-area network devices," Journal of Electrical and Computer Engineering, Vol. 2020, No. 1, 4967198, 2020. Google Scholar

17. Goswami, Niloy and Md. Abdur Rahman, "A 9.73 GHz wide-band off-body patch antenna for biomedical applications," Indonesian Journal of Electrical Engineering and Computer Science, Vol. 33, No. 1, 151-158, 2024.
doi:10.11591/ijeecs.v33.i1.pp151-158 Google Scholar

18. Raad, Haider Khaleel, Hussain M. Al-Rizzo, Ayman Abbosh, and Ali I. Hammoodi, "A compact dual band polyimide based antenna for wearable and flexible telemedicine devices," Progress In Electromagnetics Research C, Vol. 63, 153-161, 2016. Google Scholar

19. Khanna, P., A. Sharma, A. K. Singh, and A. Kumar, "A novel approach for production challenges of flexible microstrip patch antenna," Brilliant Engineering, Vol. 1, 7-12, 2019.
doi:10.36937/ben.2020.001.002 Google Scholar

20. Gil, Ignacio, Rob Seager, and Raúl Fernández-García, "Embroidered metamaterial antenna for optimized performance on wearable applications," Physica Status Solidi (A), Vol. 215, No. 21, 1800377, 2018. Google Scholar

21. Naik, Ketavath Kumar, Seelam Chaithanya Satya Teja, Bokkisam Venkata Sailaja, and Pasumarthi Amala Sri, "Design of flexible parasitic element patch antenna for biomedical application," Progress In Electromagnetics Research M, Vol. 94, 143-153, 2020. Google Scholar

22. Kumar, S. Ashok and T. Shanmuganantham, "Implantable CPW-fed rectangular patch antenna for ISM band biomedical applications," Microwave and Optical Technology Letters, Vol. 56, No. 5, 1060-1065, 2014. Google Scholar

23. Prabhu, S. and C. Tharini, "Design and analysis of flexible microstrip antennas using polyimide protection," Engineering, Technology & Applied Science Research, Vol. 14, No. 2, 289-297, 2023. Google Scholar

24. Firdaus, R. A., M. Khoiro, E. Rahmawati, Dzulkiflih, and M. Yantidewi, "Design of folded dipole antenna with stub feed line at 3.5 Ghz operating frequency for 5G cellular network," Journal of Physics: Conference Series, Vol. 2900, No. 1, 012056, 2024.

25. Nashef, Georges Zakka El, François Torrès, Sébastien Mons, Tibault Reveyrand, Edouard Ngoya, Thierry Monédière, Marc Thévenot, and Raymond Quéré, "An accurate modeling technique for antennas and nonlinear RF power amplifier mixed simulation," International Journal of Microwave and Wireless Technologies, Vol. 3, No. 6, 647-655, 2011. Google Scholar

26. Khairanisa, Nadila, Siska Aulia, Sri Yusnita, and Yulindon Yulindon, "Analyzing troubleshooting of BTS transmit power and 4G LTE coverage area via VSWR value measurement," Andalas Journal of Electrical and Electronic Engineering Technology, Vol. 3, No. 2, 82-88, 2023.
doi:10.25077/ajeeet.v3i2.57 Google Scholar

27. Lee, Chie-In, Wei-Cheng Lin, and Yan-Ting Lin, "Temperature dependence on RF avalanche breakdown of RF mosfets in the impact ionization region," Microwave and Optical Technology Letters, Vol. 57, No. 4, 817-820, 2015. Google Scholar

28. Shah, S. M., N. F. A. Kadir, Z. Z. Abidin, F. C. Seman, S. A. Hamzah, and Norshidah Katiran, "A 2.45 GHz semi-flexible wearable antenna for industrial, scientific and medical band applications," Indonesian Journal of Electrical Engineering and Computer Science, Vol. 15, No. 2, 814-822, 2019.
doi:10.11591/ijeecs.v15.i2.pp814-822 Google Scholar

29. Ali, Usman, Sadiq Ullah, Jalal Khan, Muhammad Shafi, Babar Kamal, Abdul Basir, James A. Flint, and Rob D. Seager, "Design and SAR analysis of wearable antenna on various parts of human body, using conventional and artificial ground planes," Journal of Electrical Engineering and Technology, Vol. 12, No. 1, 317-328, 2017. Google Scholar

30. Abdou, Tarek S., Rola Saad, and Salam K. Khamas, "A circularly polarized mmWave dielectric-resonator-antenna array for off-body communications," Applied Sciences, Vol. 13, No. 3, 2002, 2023. Google Scholar

31. Gandhi, Om P., "Microwave emissions from cell phones exceed safety limits in Europe and the US when touching the body," IEEE Access, Vol. 7, 47050-47052, 2019. Google Scholar

32. Shamsudin, Nur Azura and Shaharil Mohd Shah, "Miniaturized dual-band dual-mode microstrip patch antenna with defected ground structure for wearable applications," Journal of Electronic Voltage and Application, Vol. 2, No. 2, 120-128, 2021.
doi:10.30880/jeva.2021.02.02.013 Google Scholar

33. Koyama, Shin, Eijiro Narita, Yoshihisa Suzuki, Masao Taki, Naoki Shinohara, and Junji Miyakoshi, "Effect of a 2.45-GHz radiofrequency electromagnetic field on neutrophil chemotaxis and phagocytosis in differentiated human HL-60 cells," Journal of Radiation Research, Vol. 56, No. 1, 30-36, 2015. Google Scholar

34. Benkalfate, Chemseddine, Achour Ouslimani, Abed-Elhak Kasbari, and Mohammed Feham, "A new compact triple-band triangular patch antenna for RF energy harvesting applications in IoT devices," Sensors, Vol. 22, No. 20, 8009, 2022.
doi:10.3390/s22208009 Google Scholar

Mr. S. Sadhish Prabhu

Dr. Chandrapragasam Tharini