Wide Slot Circularly Polarized Conductive Oxide-based Transparent Antenna Design for ISM Band RFID Applications

A novel wide slot transparent circularly polarized antenna is illustrated in this paper. Circular polarization is achieved by using a wide slotted S-shaped loop with diagonally trimmed edges, two separate mirrored U-shaped slots with feed location at the center of the conductive patch. Conductive oxide AgHT-8 is used as a feeding patch over a 1.48 mm thick transparent plexiglass substrate (εr = 2.3, tan δ = 0.000379). The antenna operates in the band spanning from 0.80 GHz - 1.05 GHz (~27.47%) with the axial ratio (AR) less than 3 dB within the same band. Numerical studies have been carried out to analyze the performance parameters of the antenna such as reflection coefficient, gain, axial ratio, radiation pattern and it has been observed that the results are satisfactory for RFID applications as an optically transparent CP antenna.