BROADBAND CPW FED POLARIZATION RECONFIGURABLE ANTENNA FOR UNIVERSAL UHF RFID READER

Abstract

In this paper, a compact CPW fed polarization reconfigurable wideband antenna is presented for the application of a universal ultra-high frequency (UHF) radio frequency identification (RFID) antenna. In this work, long-range and random orientation detectability features are incorporated with the inclusion of polarization reconfigurability in the RFID reader antenna. Initially, a circularly polarized antenna is designed, which consists of a square slot embedded with an inverted L-shaped strip line and an F-shaped feeding structure, which is etched on the FR4_epoxy substrate. Secondly, the inclusion of three PIN diodes and an extra strip line connected to the feed structure are used to achieve linear as well as circular polarization. The desired performance is obtained in the whole UHF RFID frequency band (universally adopted range in the UHF band by the different countries) from 840 MHz to 960 MHz. Simulation, as well as experimentation procedures, are applied to obtain the details of the S11, gain, axial ratio, and radiation patterns. The experimented performance metrics are in good agreement with simulation results. The results reveal that axial ratio requirements for linear and circular polarizations are met in the required band of operation with acceptable gain.