A small printed antenna with circular slot for European UHF RFID reader devices

In this paper, a small patch antenna is designed for ultrahigh frequency (UHF) radio frequency identification (RFID) reader applications in European band. This antenna is composed of an L-shaped strip monopole line, in addition, three rectangular strip line inserted into the circular slot in the ground plane. The simulated impedance bandwidth of the proposed structure is 59 MHz and extends from 841 to 900 MHz, centered at 867.5 MHz. The radiation pattern is a bidirectional pattern with a maximum antenna gain of 2.91 dB. The overall size of the antenna is 80 × 80 × 1.6 mm
³
and printed on an FR4 substrate with dielectric permittivity constant 4.3, thickness of 1.6 mm and loss tangent of 0.02. The simulation was performed in electromagnetic solvers CST Microwave Studio and High-Frequency Structure Simulator Software (HFSS).