A planar multiport multi-circular patch MIMO antenna on flexible substrate with defected ground structure for sub-6 GHz

Hossain, Fahmida and Nor, Mohd Khanapiah Bin and Abd Aziz, Azlan and Ibrahimy, Muhammad Ibn and Hossain, A. K. M. Zakir (2026) A planar multiport multi-circular patch MIMO antenna on flexible substrate with defected ground structure for sub-6 GHz. SSRG International Journal of Electrical and Electronics Engineering, 13 (9). pp. 17-32. ISSN 2348-8379

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Abstract

In this proposed work, a flexible planar six-port Multiple-Input Multiple-Output (MIMO) microstrip antenna is presented that is intended for sub-6 GHz Fifth Generation (5G), wearable, and biomedical wireless applications. The antenna employs a multi-circular radiating patch topology. It is integrated with a Partial Ground Plane (PGP) and a Defected Ground Structure (DGS) techniques to achieve wideband impedance matching, reduced mutual coupling, and improved diversity characteristics. The single antenna element occupies a small space of 38.40 × 24 × 0.508 mm³, whereas the complete six-port configuration is arranged on a 165 × 76 mm² flexible Kapton platform corresponding to the dimensions of a 6.67-inch smartphone. The practical measurements demonstrate a wide bandwidth of 3.0-6.6 GHz, which includes all available sub-6 GHz 5G mid-band frequencies. The measured inter-port isolation remains greater than 35 dB and reaches approximately 58 dB for selected port combinations. The Envelope Correlation Coefficient (ECC) is maintained below 0.5, with a minimum of 1.15 ×10-5 while the Diversity Gain (DG) remains close to 10 dB. The Mean Effective Gain (MEG) is approximately 3 dB for all ports, with inter-port differences close to 0 dB. Practical line-of-sight measurements produce received-power levels ranging from - 37.24 to -22.92 dBm. The antenna also preserves stable operation during on-body placement and mechanical bending. Moreover, the maximum specific absorption rate values are 0.775 W/kg averaged over 1 g of tissue and 0.335 W/kg averaged over 10 g, remaining within the applicable exposure limits.

Item Type:	Article (Journal)
Uncontrolled Keywords:	MIMO, Flexible antenna, Defected ground structure, Sub-6 GHz, Kapton substrate, SAR.
Subjects:	T Technology > T Technology (General) > T10.5 Communication of technical information
Kulliyyahs/Centres/Divisions/Institutes (Can select more than one option. Press CONTROL button):	Kulliyyah of Engineering > Department of Electrical and Computer Engineering
Depositing User:	Dr Muhammad Ibrahimy
Date Deposited:	05 Oct 2026 17:15
Last Update:	05 Oct 2026 17:15
Queue Number:	2026-09-Q5423
URI:	http://irep.iium.edu.my/id/eprint/131690
Indexed In:	Google Scholar

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