A Reading Range- and Frequency-Reconfigurable Antenna for Near-Field and Far-Field UHF RFID Applications

Area of Science:

• Electrical Engineering
• Electromagnetics
• Antenna Theory

Background:

• Radio Frequency Identification (RFID) systems face challenges due to varying international spectrum policies and tag misreading.
• Existing RFID reader antennas often lack the flexibility to adapt to diverse global regulations and operational requirements.

Purpose of the Study:

• To propose a reconfigurable antenna for Ultra-High Frequency (UHF) RFID readers that overcomes limitations imposed by different spectrum policies.
• To enhance both near-field and far-field RFID reading capabilities through a single, adaptable antenna design.

Main Methods:

• Utilizing a composite right/left-handed transmission line (CRLH-TL) based on a periodically capacitive gap-loaded parallel plate line.
• Achieving zeroth-order resonance in the CRLH-TL to create a loop antenna with in-phase radiating current for a strong H-field and omnidirectional pattern.
• Incorporating tunable components to enable frequency and reading range adjustments.

Main Results:

• The antenna demonstrates a frequency tuning range from 833 MHz to 979 MHz, covering the global UHF RFID band.
• Each operational mode exhibits a narrow frequency band, facilitating compliance with diverse national radio frequency policies.
• Adjustable near-field interrogation zone (400 mm × 400 mm × 50 mm) and a tunable far-field reading distance (0.35 m to 2.71 m) were achieved.

Conclusions:

• The proposed CRLH-TL reconfigurable antenna effectively addresses spectrum policy variations and enhances RFID system flexibility.
• The design simplifies the development of multi-version RFID readers by offering a single, adaptable solution.
• This antenna technology offers significant improvements for both near-field and far-field RFID applications, enabling wider global adoption.