Circularly polarized unidirectional antenna using planar tennis shape structure

Abstract

This paper presents the study and the design of the circularly polarized reader antenna with a tennis ball-shaped radiating plate operating at the universal UHF band (860-960 MHz). The proposed antenna is excited by a capacitively coupled feed technique to enhance S11. The tennis ball-shaped radiating plate can be generated a circularly polarized radiation. The simulation is studied effect of the parameters of the proposed antenna for cover the universal UHF RFID band. The prototype antenna is achieved, S11 cover the frequency between 837.60 to 966.20 MHz, the 3-dB axial ratio (AR) bandwidth cover the frequency from 850.60 to 963.50 MHz, a unidirectional radiation pattern and an average gain 6.18 dBic, respectively.