Handheld radio frequency identification (RFID) reader units become increasingly important with the adoption of passive ultra-high frequency (UHF) RFID systems in supply chain, warehouse and retail store management. Important requirements for the handheld reader unit are ergonomic size and weight, sufficient battery life and suitable read range for the desired applications. In addition, usability of the reader unit in terms of reading directions and orientations of tags has to be taken into account. This paper presents a performance comparison of compact reader antennas for a handheld UHF RFID reader unit. The reader antennas presented in this study are designed to be affixed either inside the casing of the reader unit or into an external reader antenna module. The presented antenna designs have been optimized with finite element method (FEM) modeling. The resonance frequency and bandwidth characteristics are analyzed using modeled and measured results. Read range measurement results with the antenna designs affixed to the handheld reader are presented and analyzed to verify the practical performance. All the antenna designs presented in this paper are applicable to a handheld RFID reader unit.
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