UHF 대역 RFID 안테나 설계

Abstract

This paper reports the characteristics and designs of RFID antennas operating at UHF band. Antennas for RFID application should work with high efficiency, a lpw return loss and a good antenna gain ti achieve the required readable range with the restricted system power. Especially, for reader antennas, the high quality of a circular porization (CP) in a wide range of frequency is strongly required and the proper radiation pattern is needed to broaden the readable range of the system. For tag antennas, the small and the planar profile is desired to be easily attatched to an object and the stable radiation performance nearby various dielectric material is required.In addition, the readable range of the tag should not change much depending on its rotation angle,. In this paper, we propose a novle reader antenna, called multi-layered polygonar helix. on which the wireis wound around multi-layered polygons causing the pitch angle to both increase and decrease. We also propose two different types of tag antennas. One is to miniaturize the electric size ot the tag and the other is to achieve an omni-directional readale range so that the tag can be stably detected irrespective of its rotation angle. The detail design parameters for the both the reader and tag antennas are determined using a Pareto Genetic Algorithm in conjunction with numerical simulation code such as Numerical Electromagnetics Code (NEC) and IE3D. Then, we fabricated the samples of the optimized antennas on the low cost substrate materials and compared the measurement results to the simulations.