UWB Circular Polarization RFID Reader Antenna for 2.4 GHz Band

摘要

Ultra Wide Band (UWB) left hand, right hand circularly polarized antenna is proposed for the supper high frequency (SHF) 2.4-2.483 GHz Radio Frequency Identification (RFID) applications. The antenna is composed of three layers, upper FR4 layer with circular slotted patch antenna on the top, middle foam layer, bottom FR4 layer with modified branch line coupler on the top and ground plane on the bottom of this layer. The slotted circular patch is fed by two posts connecting the circular patch through the foam layer with the branch line coupler. The antenna achieves impedance bandwidth of 1.66 GHz from 2.34-4 GHz for both left hand and right hand circular polarization operation which agree well with the computed results. The proposed antenna has 3dB axial ratio bandwidth of 488 MHz for the left hand circular polarization covering the range 2.37299-2.86174 GHz and 591 MHz for the right hand circular polarization covering the range 232154-2.91318 GHz. The proposed antenna offers an acceptable gain and other antenna parameters within its bandwidth.