Dual Purpose Near- and Far-Field UHF RFID Coil Antenna With Non-Uniformly Distributed-Turns

An Ultra-High-Frequency (UHF) Radio Frequency IDentification (RFID) coil antenna with Non-uniformly Distributed-Turns and realized using a segmented-line (SL) is proposed. The Segmented-Line Non-uniformly Distributed-Turns Coil (SL-NDTC) uses non-uniformly distributed turns radii that have been optimized for reactive and radiative read performance. This leads to a dual purpose near- and far-field antenna in a single unit. Simulations show a more focused magnetic-field (H-field) distribution in the near field of the SL-NDTC compared to more conventional coils. Single and dual turn designs are compared to the SL-NDTC antenna to evidence enhanced near- and far-field performance in the latter.