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.
2. Lei, J., et al., "An omnidirectional printed dipole array antenna with shaped radiation pattern in the elevation plane," Journal of Electromagnetic Waves and Applications, Vol. 20, No. 14, 1955-1966, 2006.
3. Ayestaran, R. G., J. Laviada, and F. Las-Heras, "Synthesis of passive-dipole arrays with a genetic-neural hybrid method," Journal of Electromagnetic Waves and Applications, Vol. 20, No. 15, 2123-2135, 2006.
4. Fan, Z. G., et al., "Signal descriptions and formulations for long range UHF RFID readers," Progress In Electromagnetics Research, Vol. 71, 109-127, 2007.
5. Fan, Z. G., L. X. Ran, and J. A. Kong, "Source pulse optimizations for UWB radio systems," Journal of Electromagnetic Waves and Applications, Vol. 20, No. 11, 1535-1550, 2006.
6. Fan, Z. G., L. X. Ran, and K. S Chen, "Novel printed dipole antenna with reflecting structure of V-shaped ground plane," Journal of Zhejiang University (Engineering Science), Vol. 39, No. 9, 1292-1295, 2005.
7. Chuang, H. R. and L. C. Kuo, "3-D FDTD design analysis of a 2.4- GHz polarization-diversity printed dipole antenna with integrated balun and polarization-switching circuit for WLAN and wireless communication applications," IEEE Transactions on Microwave Theory and Techniques, Vol. 51, No. 2, 374-381, 2003.
8. Baward, R. and J. J. Wolfe, "A printed circuit balun for use with spiral antennas," IRE Transactions on Microwave Theory and Techniques, Vol. 8, No. 3, 319-325, 1960.
9. Edward, D. and D. Rees, "A broadband printed dipole with integrated balun," Microwave Journal, No. 5, 339-344, 1987.
10. Butler, C. M., "A formulation of the finite-length narrow slot or strip equation," IEEE Transactions on Antennas and Propagation, Vol. 30, No. 6, 1254-1257, 1982.
11. Butler, C. M., "The equivalent radius of a narrow conducting strip," IEEE Transactions on Antennas and Propagation, Vol. 30, No. 4, 755-758, 1982.
12. Zhou, C. D., Y. K. Wang, and L. M. Zhou, Theory and Engineering on Line Antennas, 27-37, 27-37, Xidian University Press, Xian, 1988.