Frequency and Polarization Agile RFID Patch Antenna with Reduced Dimensions

This paper presents a frequency and polarization reconfigurable UHF RFID patch antenna based on a switchable feeding network. For best integration of the antenna, its size and ground plane are much smaller with respect to the canonical patch antenna design, however the proposed design is able to cover the EU and US frequency bands of the RFID standard. State-of-the-art CMOS switches are employed as key element for selecting the desired polarization and proper matching network. The switches provide also a simple solution for high power applications in contrast to concepts based on PIN diodes or varactors. Simulated results have shown good performance. Considering its flexible and inexpensive structure, the proposed system is a promising alternative to aperture tuning and circular polarized antenna approaches.