Citation

Jizat, Noorlindawaty Md. and Mahmud, Azwan and Zainudin, Norsiha and Muhsin, M. and Yamada, Yoshihide (2025) Input Resistance Step-Up of Normal-Mode Helical Antennas (NMHA) using Dual and Triple-Folded Structures. In: 2025 International Symposium on Antennas and Propagation (ISAP), 27-31 October 2025, Fukuoka, Japan.

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Abstract

RFID systems require compact, high-performance antennas for UHF operation at 921 MHz, which can work reliably near metallic. This can be challenging due to issues like detuning and low efficiency. Folded dipole, meander line, and helical antennas are often used to improve the performance. However, research on using Normal Mode Helical Antennas (NMHAs) for this purpose is limited. NMHAs are attractive because NMHA provide a purely resistive input impedance at resonance, but their small size leads to low input resistance. To address this, a step-up impedance design is proposed. The paper presents a compact folded helical NMHA that increases input resistance, about fourfold for a two-element design and eightfold for a three-element design. Simulations show better impedance matching and enhanced performance near metallic surfaces, making this design ideal for RFID tags.

Item Type:	Conference or Workshop Item (Paper)
Uncontrolled Keywords:	RFID, step-up, folded helical, current, impedance, gain
Subjects:	T Technology > TK Electrical engineering. Electronics Nuclear engineering > TK5101-6720 Telecommunication. Including telegraphy, telephone, radio, radar, television
Divisions:	Faculty of Artificial Intelligence & Engineering (FAIE)
Depositing User:	Ms Suzilawati Abu Samah
Date Deposited:	20 Apr 2026 02:58
Last Modified:	20 Apr 2026 02:58
URII:	http://shdl.mmu.edu.my/id/eprint/15761

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