Circularly Polarized, Aperture-coupled Patch Antennas for a 2.4 GHz RFID System

Abstract

Antennas are key components of microwave RF identification (RFID) tagging systems because miniaturization of the transponder or tag is limited mainly by the antenna dimensions. Printed antennas are widespread in RFID systems due to their minimal processing costs. Compared to a classical patch antenna, aperture-coupled patch antennas offer an improvement in terms of the optimization of radiation characteristics and antenna size. The RFID system is operated in the 2.4 GHz industrial, scientific and medical (ISM) band. Due to the requirements of the modulation scheme, the aperture-coupled patch antennas are circularly polarized with switchable polarization sense.