RFID Tag Reading Effects of Cylindrical Conductive Packages

We study two classes of passive UHF RFID tag antennas: bowties and slots, on conductive cylinders. We find better performance can be achieved when the tag is cross-polarized with the main axis of cylindrical containers. The performance degradation under co-polarization can be attributed to the reduction of radiation efficiency and the detuning of antenna impedance due to the stronger scattering interference from the metallic package. Our results serve as a general guideline to determine the right tag orientation for reliable readability