Dual-band circularly polarized wearable patch antenna for RFID Reader

Abstract

In the proposed work, a compact Circularly Polarized (C.P.) Radio Frequency Identification (RFID) antenna has been designed for global microwave bands, i.e., 2.4 GHz and 5.8 GHz for wearable wireless applications. To achieve circular polarization, traditional truncated opposite corners of the patch are introduced, resulting in an orthogonal electric field in the X and Y direction. Another truncated square slot patch miniaturizes the antenna, provides a dual band frequency response and the patch is finally placed on flexible wearable dielectric material. The Defective Ground Structure (DGS) is used to enhance the designed antenna's gain and bandwidth. The simulation result shows the radiated gain of 6.5 dBi at 2.4 GHz and 10dBi at 5.8 GHz. For better impedance matching, the return loss (S11) of −19.5 dB at 2.4 GHz and −45 dB at 5.8 GHz is achieved. The antenna is circularly polarized with an axial ratio bandwidth below 3dB for the wide range reading of RFID tags. The designed antenna provides better isolation to the Electromagnetic Interference (EMI) caused due to adjacent frequencies since it radiates at two frequencies only.