Miniature and near-3D omnidirectional radiation pattern RFID tag antenna design

A planar and miniature (0.09lambda times 0.13lambda) radio frequency identification (RFID) tag antenna is described whose radiation pattern is near omni-directional in three dimensions, with less than 2.6 dB gain deviation in all directions. The antenna is comprised of an open-loop radiating element, which is excited by a small loop. The minimum and maximum read ranges of the implemented RFID tag are approximately 2.3 and 2.6 m, respectively. Comparison between the simulated and measured results for the radiation and read patterns are shown to be in good agreement.