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A wideband decoupling method using bezel-coupled loop-type isolator for smartwatch MIMO applications

Published online by Cambridge University Press:  13 July 2022

Babar Aslam Baloch ,
Longyue Qu Open the ORCID record for Longyue Qu [Opens in a new window] ,
Zeeshan Zahid Open the ORCID record for Zeeshan Zahid [Opens in a new window]  and
Adnan Ahmed Khan
Babar Aslam Baloch
Affiliation:
Department of Electrical Engineering, Military College of Signals, National University of Sciences and Technology, Islamabad, Pakistan
Longyue Qu
Affiliation:
School of Electronics and Information Engineering, Harbin Institute of Technology, Shenzhen, China
Zeeshan Zahid*
Affiliation:
Department of Electrical Engineering, Military College of Signals, National University of Sciences and Technology, Islamabad, Pakistan
Adnan Ahmed Khan
Affiliation:
Department of Electrical Engineering, Military College of Signals, National University of Sciences and Technology, Islamabad, Pakistan
*
Author for correspondence: Zeeshan Zahid, E-mail: zeeshanzahid@mcs.edu.pk
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Abstract

This paper presents a novel decoupling technique for two-element multiple-in multiple-out (MIMO) antennas for smartwatch applications with floating metallic bezel. The radiating elements consist of embedded loop-type ground-radiation antennas and operate at the 2.45 GHz Bluetooth/Wi-Fi bands. An isolator, consisting of a loop-type structure with a lumped capacitor, is attached externally to the ground plane such that wideband isolation between the antennas has been achieved. It is demonstrated that the small-sized isolator is coupled with the large-sized bezel surrounding the ground plane, where the bezel operates as a low-Q decoupler between the antenna elements producing wideband isolation property. Accordingly, optimized results can be obtained by controlling the location of the isolator, the gap between the isolator and the bezel, and the loaded capacitor. Simulation and measured results have been presented to validate the design performance. The measured −10 dB impedance bandwidth of both antenna elements is more than 210 MHz, whereas the isolation bandwidth is 770 MHz with reference to 20 dB. The envelop correlation coefficient is <0.1 in the operating band. Furthermore, the proposed technique is versatile regardless of the angular separation of the antenna elements on the circular ground plane, which makes it a good candidate for smartwatch MIMO applications in practical scenarios.

Keywords

CouplingECCground-radiation antennamobile devicemultiple-in multiple-out (MIMO)smartwatchwideband isolation
Type
Antenna Design, Modeling and Measurements
Information
International Journal of Microwave and Wireless Technologies , Volume 15 , Issue 4 , May 2023 , pp. 698 - 708
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Copyright
© The Author(s), 2022. Published by Cambridge University Press in association with the European Microwave Association

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References

Hall, PS and Hao, Y (2012) Antennas and Propagation for Body-Centric Wireless Communications, 2nd Edn. Norwood, MA: Artech House.Google Scholar
Chen, WS, Lin, GQ and Hsu, WH (2017) “WLAN MIMO antennas with a GPS antenna for smart watch applications”, International Workshop on Electromagnetics: Applications and Student Innovation Competition. doi: 10.1109/iWEM.2017.7968771CrossRefGoogle Scholar
Jeon, M, Choi, WC and Yoon, YJ (2016) “GPS, Bluetooth and Wi-Fi tri-band antenna on metal frame of smartwatch,” in Proceedings of IEEE International Symposium on Antennas and Propagation (APSURSI), Fajardo, Puerto Rico, Jul. 2016, 2177–2178. doi: 10.1109/APS.2016.7696795CrossRefGoogle Scholar
Su, S-W and Hsieh, Y-T (2015) Integrated metal-frame antenna for smartwatch wearable device. IEEE Transactions on Antennas and Propagation 63, 3301–3305.CrossRefGoogle Scholar
Wu, D and Cheung, SW (2017) A cavity-backed annular slot antenna with high efficiency for smartwatches with metallic housing. IEEE Transactions on Antennas and Propagation 65, 3756–3761.CrossRefGoogle Scholar
Wen, D, Hao, Y, Wang, H and Zhou, H (2017) “A wearable antenna design using a high impedance surface for all-metal smartwatch applications,” in Proceedings of the Internatoional Workshop on Antenna Technology, Small Antennas, Innovative Structures, and Applications (iWAT), Athens, Greece, pp. 274–276.Google Scholar
Werner, DH and Jiang, ZH (2016) “Electromagnetics of body area networks: antennas, propagation, and RF systems” Wiley Publishers, 2016; ISBN: 978-1-119-02946-5.Google Scholar
Jensen, MA and Wallace, JW (2004) A review of antennas and propagation for MIMO wireless communications. IEEE Transactions on Antennas and Propagation 52, 2810–2824.10.1109/TAP.2004.835272CrossRefGoogle Scholar
Chen, Y-S and Ku, T-Y (2015) A low-profile wearable antenna using a miniature high impedance surface for smartwatch applications. IEEE Antennas and Wireless Propagation Letters 15, 1144–1147.CrossRefGoogle Scholar
Wen, D, Hao, Y and Wang, H (2019) Design of a MIMO antenna with high isolation for smartwatch applications using the theory of characteristic modes. IEEE Transactions on Antennas and Propagation 67, 1437–1447.CrossRefGoogle Scholar
Wang, B and Yan, S (2020) Design of smartwatch integrated antenna with polarization diversity. IEEE Access 8, 123440–123448.CrossRefGoogle Scholar
Li, WW, Zhou, JH, Zhang, B and You, BQ (2013) High isolation dual-port MIMO antenna. Electronics Letters 49, 919–921.CrossRefGoogle Scholar
Chen, W-S, Yang, CK and Sin, W-S (2015) “MIMO antenna with Wi-Fi and Bluetooth for smart watch applications”, Sep. 2015; in Proceedings of the IEEE MTT-S International Microwave Workshop Series (IMWS), Taipei, Taiwan, 212–213.Google Scholar
Woo, S, Baek, J, Park, H, Kim, D and Choi, J (2013) “Design of a compact UWB diversity antenna for WBAN wrist-watch applications,” in Proceedings of the ISAP, Nanjing, China, Oct. 2013, 1304–1306.Google Scholar
Govindan, T, Palaniswamy, SK, Kanagasabai, M, Thipparaju, RR, Alsath, GN, Kumar, S, Velan, S, Marey, M and Aggarwal, A (2021) On the design and performance analysis of wristband MIMO/ diversity antenna for smart wearable communication applications. Nature Scientific Reports 11, 21917, 1–14.CrossRefGoogle ScholarPubMed
Cho, O, Choi, H and Kim, H (2011) Loop-type ground antenna using capacitor. Electronics Letters 47, 11–12.CrossRefGoogle Scholar
Liu, Y, Lu, X, Jang, H, Choi, H, Jung, K and Kim, H (2011) Loop-type ground antenna using resonated loop feeding, intended for mobile devices. Electronics Letters 47, 426–427.CrossRefGoogle Scholar
Liu, Y, Kim, HH and Kim, H (2013) Loop type ground radiation antenna for dual band WLAN applications. IEEE Transactions on Antennas and Propagation 61, 4819–4823.CrossRefGoogle Scholar
Zahid, Z and Kim, H (2017) Analysis of loop type ground radiation antenna using equivalent circuit model. IET Microwaves, Antennas & Propagation 11, 23–28.CrossRefGoogle Scholar
Zahid, Z and Kim, H (2019) Coupling mechanism of loop type ground radiation. ETRI Journal 41, 528–535.CrossRefGoogle Scholar
Garbacz, R and Turpin, R (1971) A generalized expansion for radiated and scattered fields. IEEE Transactions on Antennas and Propagation 19, 348–358.CrossRefGoogle Scholar
Harrington, R and Mautz, J (1971) Theory of characteristic modes for conducting bodies. IEEE Transactions on Antennas and Propagation 19, 622–628.CrossRefGoogle Scholar
Marta, CF, Eva, AD, Daviu, EA, Nogueira, AV and Bataller, MF (2007) The theory of characteristic modes revisited: a contribution to the design of antennas for modern applications. IEEE Antennas and Propagation Magazine 5, 52–68.Google Scholar
Deng, C, Feng, Z and Hum, SV (2016) MIMO mobile handset antenna merging characteristic modes for increased bandwidth. IEEE Transactions on Antennas and Propagation 64, 2660–2667.CrossRefGoogle Scholar
Liu, XZ, Yu, G, Chao, J, Zhang, HH and Liu, Y. “TCM-based low-SAR MIMO antenna for smartwatch applications” 2021 International Conference on Microwave and Millimeter Wave Technology (ICMMT). doi: 10.1109/ICMMT52847.2021.9617881.CrossRefGoogle Scholar
Qu, L, Zhang, R and Kim, H (2016) Decoupling between ground radiation antennas with ground coupled loop-type isolator for WLAN applications. IET Microwaves, Antennas & Propagation 10, 546–552.CrossRefGoogle Scholar
Zahid, Z and Kim, H (2018) Decoupler design for MIMO antennas of USB dongle applications using ground mode coupling analysis. Progress in Electromagnetics Research M 76, 113–122.CrossRefGoogle Scholar
Qu, L, Piao, H, Qu, Y, Kim, H-H and Kim, H (2018) Circularly polarised MIMO ground radiation antennas for wearable devices. Electronics Letters 54, 189–190.CrossRefGoogle Scholar
Pozar, DM (2011) Microwave Engineering, 4th Edn. Hoboken, NJ: John Wiley & Sons, Inc.Google Scholar
Harrington, RF (2001) Time Harmonic Electromagnetics, 2nd Edn. New York: Wiley IEEE Press.CrossRefGoogle Scholar
Altair. CADFEKO Suite14.0. Available at https://www.altair.com/feko.Google Scholar
Zainud-Deen, SH, Hassan, WM and Malhat, HA (2016) Near-field focused folded transmitarray antenna for medical applications. ACES Journal 31, 315–320.Google Scholar
Li, G, Gao, G, Bao, J, Yi, B, Song, C and Bian, L-A (2017) A watch strap antenna for the applications of wearable systems. IEEE Access 5, 10332–10338.10.1109/ACCESS.2017.2715186CrossRefGoogle Scholar
IEEE std C95.1–1991 (2005) IEEE Standard for Safety Levels with Respect to Human Exposure to Radio Frequency Electromagnetic Fields, 3 kHz to 300 GHz. New York: IEEE Inc.Google Scholar
Yan, S and Vandenbosch, GAE (2018) Design of wideband button antenna based on characteristic mode theory. IEEE Transactions on Biomedical Circuits and Systems 12, 1383–1391.CrossRefGoogle ScholarPubMed
Vaughan, RG and Andersen, JB (1987) Antenna diversity in mobile communications. IEEE Transactions on Vehicular Technology 36, 149–172.CrossRefGoogle Scholar
Sharawi, M, Hassan, A and Khan, M (2017) Correlation coefficient calculations for MIMO antenna systems: a comparative study. International Journal of Microwave and Wireless Technologies 9, 1991–2004. doi: 10.1017/S1759078717000903CrossRefGoogle Scholar
Sharawi, MS, Khan, MU, Numan, AB and Aloi, DN (2013) A CSRR loaded MIMO antenna system for ISM band operation. IEEE Transactions on Antennas and Propagation 61, 4265–4274.CrossRefGoogle Scholar
Zahra, H, Awan, WA, Ali, WAE, Hussain, N, Abbas, SM and Mukhopadhyay, AA (2021) 28 GHz Broadband helical inspired end-fire antenna and its MIMO configuration for 5 G pattern diversity applications. Electronics 10, 405.CrossRefGoogle Scholar