A miniaturized printed dipole antenna with V-shaped ground for 2.45 GHz RFID readers

In this paper, a miniaturized printed dipole antenna with the V-shaped ground is proposed for radio frequency identification ( RFID) readers operating at the frequency of 2.45 GHz. The principles of the microstrip balun and the printed dipole are analyzed and design considerations are formulated. Through extending and shaping the ground to reduce the coupling between the balun and the dipole, the antenna's impedance bandwidth is broadened and the antenna's radiation pattern is improved. The 3D finite difference time domain ( FDTD) Electromagnetic simulations are carried out to evaluate the antenna's performance. The effects of the extending angle and the position of the ground are investigated to obtain the optimized parameters. The antenna was fabricated and measured in a microwave anechoic chamber. The results show that the proposed antenna achieves a broader impedance bandwidth, a higher forward radiation gain and a stronger suppression to backward radiation compared with the one without such a ground.