Wideband Koch Fractal Technique for Intelligent Reflecting Surface Application

Authors

DOI:

https://doi.org/10.14500/aro.12928

Keywords:

Fractal geometry, Intelligent reflecting surface, Koch fractal, Metasurface, Reflection phase, Wideband metasurface, X-band

Abstract

This paper presents a wideband X-band IRS based on a novel combined inward–outward Koch fractal metasurface. The proposed unit cell integrates inward and outward Koch fractal geometries to increase the effective electrical current path and support multiple resonant modes, thereby enhancing the reflection bandwidth while maintaining a compact single-layer structure. A 300 × 300 mm² IRS prototype was designed, fabricated, and experimentally validated. Simulation results demonstrate a reflection phase bandwidth of 2.40 GHz (8.95–11.35 GHz), while measurements confirm a bandwidth of 2.25 GHz (8.90–11.15 GHz), corresponding to a fractional bandwidth of 22.44%. The measured reflection magnitude and phase responses are in good agreement with the simulated results. System-level experiments conducted in a non-line-of-sight environment further demonstrate that the proposed IRS improves the received signal strength by more than 15 dB compared with the case without an IRS, confirming its capability to redirect electromagnetic waves and enhance wireless coverage effectively. The combination of wideband performance, compact single-layer construction, and experimentally verified signal enhancement demonstrates the potential of the proposed combined Koch fractal IRS for next-generation intelligent wireless communication systems.

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Author Biographies

Nur S. Mohd Yaziz, Advanced RF and Microwave Research Group, Faculty of Electrical Engineering, Universiti Teknologi Malaysia, Johor Bahru, Johor, Malaysia

Nur S. Mohd Yaziz is a postgraduate student at the Department of Communication Engineering, Faculty of Electrical Engineering, Universiti Teknologi Malaysia. She got the B. Electrical degree in telecommunication engineering (2015) and the M.E. degree in electrical engineering (2018) from Universiti Teknologi Malaysia. She is currently pursuing a PhD degree in Communication Engineering at the Faculty of Electrical Engineering, Universiti Teknologi Malaysia. Her research interests are RF and microwave systems, antennas, fractal geometry, intelligent reflecting surfaces, and their
applications.

Mohamad Kamal A. Rahim, Advanced RF and Microwave Research Group, Faculty of Electrical Engineering, Universiti Teknologi Malaysia, Johor Bahru, Johor, Malaysia

Mohamad Kamali A. Rahim s a Professor at the Department of Communication Engineering, Faculty of Electrical Engineering, Universiti Teknologi Malaysia. He got the B. Eng. Degree in electrical and electronic engineering from the University of Strathclyde, U.K in 1987, the master’s degree in engineering from the University of New South Wales, Australia, in 1992, and the PhD degree in the field of wideband active antenna from the University of Birmingham, U. K in 2003. His research interests are in active and passive antennas, dielectric resonator antennas, microstrip antennas, reflectarray antennas, electromagnetic bandgap, artificial magnetic conductors, and left-handed metamaterials. Prof. Kamal is a Senior Member, IEEE.

Farid Zubir, Wireless Communication Centre, Faculty of Electrical Engineering, Universiti Teknologi Malaysia, Johor Bahru, Johor, Malaysia

Farid Zubir is a Senior Lecturer at the Department of Communication Engineering, Faculty of Electrical Engineering, Universiti Teknologi Malaysia (UTM). He is also a Research Fellow with the Wireless Communication Centre at UTM. He got the B.Eng. degree in Electrical (Telecommunication) from UTM in 2008, the M.Eng. degree in RF and Microwave from UTM in 2010, and the Ph.D. degree from the University of Birmingham, U.K., in 2016. He was a Postdoctoral Research Fellow with the University of British Columbia (UBCO), Canada, from 2019 to 2021. His research interests are in RF and microwave technologies, power amplifiers, antennas, satellite communication, and microwave devices. Dr. Farid is a Member of IEEE.

Salah I. Yahya, Department of Computer Technology Engineering, College of Technical Engineering, Al-Hadba University, Mosul, Iraq

Salah I. Yahya is a Professor at the Department of Computer Technology Engineering, College of Technical Engineering, Al-Hadba University, Mosul, Iraq. He received the B.Sc. degree in electrical engineering, the M.Sc. degree in electronics and communication engineering, and the Ph.D. degree in communication and microwave engineering. He is a Consultant Engineer and a Senior Member of IEEE. His research interests include antenna design, numerical RF dosimetry, MW measurement, and MW
components design.

Noor Asmawati Samsuri, Advanced RF and Microwave Research Group, Faculty of Electrical Engineering, Universiti Teknologi Malaysia, Johor Bahru, Johor, Malaysia

Noor Asmawati Samsuri is a Senior Lecturer the Department of Communication Engineering, Faculty of Electrical Engineering, Universiti Teknologi Malaysia. She got the B.Eng. (Hons.) in Electrical–Telecommunication Engineering from Universiti Teknologi Malaysia (UTM) in 2001, her M.Sc. in Digital Communications Systems from Loughborough University, UK, in 2004, and her Ph.D. in Electronic and Electrical Engineering from Loughborough University, UK, in 2009. Her research interests focus on wearable antennas and their interactions with the human body and metallic structures, implantable antennas for medical telemetry, and Specific Absorption Rate (SAR) analysis. Dr. Asmawati is a Member, IEEE.

Taufiqqurrachman, Advanced RF and Microwave Research Group, Faculty of Electrical Engineering, Universiti Teknologi Malaysia, Johor Bahru, Johor, Malaysia

Taufiqqurrachman is a postgraduate student at the Department of Communication Engineering, Faculty of Electrical Engineering, Universiti Teknologi Malaysia (UTM). He got his B.Sc. in Electrical Engineering from the University of Indonesia in 2007 and his M.Sc. in Electrical Engineering from the National Taiwan University of Science and Technology in 2018. He is currently pursuing a PhD degree in Communication Engineering, at the Faculty of Electrical Engineering, UTM. His research interests include metamaterials and metasurfaces for microwave device applications.

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Published

2025-09-18

How to Cite

Mohd Yaziz, N. S. (2025) “Wideband Koch Fractal Technique for Intelligent Reflecting Surface Application”, ARO-THE SCIENTIFIC JOURNAL OF KOYA UNIVERSITY, 14(2), pp. 53–62. doi: 10.14500/aro.12928.

Issue

Vol. 14 No. 2 (2026): Edition Twenty Seven

Section

Articles

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Copyright (c) 2025 Nur S. Mohd Yaziz, Mohamad Kamal A. Rahim, Farid Zubir, Salah I. Yahya, Noor Asmawati Samsuri, Taufiqqurrachman

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Received 2026-03-10
Accepted 2026-08-16
Published 2025-09-18

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