A CPW-Fed Optically Transparent Broadband Circularly Polarized WLAN Radio Frequency Identification Reader Antenna

In this paper, an optical transparent broadband circularly polarized (CP) radio frequency identification (RFID) reader antenna is presented. The proposed antenna is composed of a soda-lime glass medium and an Indium tin oxide (ITO) layer with 1200nm thickness coated on one side of the medium plate as the conductive layer, with a transparency of more than 80%. The impedance bandwidth and 3dB axial ratio (AR) bandwidth of the antenna are 2.96GHz (1.68-4.64 GHz, 93.67% centered at 3.16 GHz)and 870MHz (2.20-3.07 GHz, 33.01% centered at 2.64 GHz), respectively. The antenna size is 48 × 48 × 1.1 mm
³
. The radiation efficiency is higher than 50% among the WLAN low frequency band (2.4-2.4835 GHz). Moreover, it has the advantages of optical transparency and wide CP bandwidth, which make it have a wide range of application scenarios.