A cross-polar orientation insensitive chipless RFID tag

Recently, Chipless RFID systems have been developed significantly and going to become commercialized in the near future. One of the critical challenges in chipless RFID systems is eliminating high reflections from the items behind the tag, which caused interference in the tag ID measurement process. One approach to combat this problem in tag design level is using a cross-polar chipless RFID tag. However, common cross-polar chipless RFID tags are usually sensitive to the orientation and can be detected only in specific orientations. This limitation of the conventional cross-polar tags makes the technology impractical for the applications in which the orientation of the tag is unknown. In this paper, a cross-polar chipless RFID is proposed which has an insensitive response to the 2D orientations. The tag can be used for tagging the objects which have high reflective and high absorptive materials such as metal and water-based liquids respectively. The provided simulation and measurement results in this paper prove this concept.