UHF RFID 리더기용 이중구조형 z-슬롯 안테나의 등방성 패턴 특성

Abstract

In this thesis, characteristics of a dual-structure z-slot antenna with isotropic pattern for the UHF RFID Reader were analyzed. In order to analyze characteristics of the dual-structure z-slot antenna, the 12 slots on the radiation plate were shaped under different parameter conditions with diagonal length (L), line length (d), the slot gap (t). The dual-structure z-slot antenna had an insertion loss of 0.16 dB in order to accurately without error recognize multiple tags from a wide range of distance at the same time and had 90 ° phase difference compare with original signal using Hybrid Coupler with 90 ° phase difference. Also, 2 Strip Line having λ / 2 of the length was designed to split into two straight signal that were same amplitude as right angle to each other. z-slot antenna had a left-turn circular polarization. 12 z-slot antenna samples were prepared by connecting λ/2 Strip Line feed point and z-slot on the radiation plate with cross-sectional area of 13.4cm x 13.4cm in order to receive micro power reflected from the tag. The designed antenna and the standard antenna were rotated in the horizontal and vertical directions respectively and then the isotropic pattern was measured by 48 kinds of experimental methods and we have obtained the antenna prameter with optimal isotropic pattern characteristics. Characterization of the designed antenna were as follows. Return Loss (S11) was very low approximately -62.21 ㏈ from 925.25 ㎒ and VSWR was from 1.001 to 1.028 by matching impedance matching of 50.069Ω from 925.25㎒. Through these characteristics, we confirmed that this was compatible with commercially available RFID readers. Also, through experiments of the dual-structure z-slot on the radiation plate with isotropic pattern, pattern characteristics were good by checking high antenna gain and deviation of less of isotropic gain when line length (d) was large and slot interval (t) was small under the same conditions of diagonal length (L) measuring from isotropic pattern and gain of antenna according to the parameters of experimental conditions. In particular, it was found that excellent characteristics showing antenna gain was level of commercialization of 7.36 dBi values that was a slight decrease compared to other conditions of experimental methods and was almost no deviation from the isotropic gain patterns when the conditions of the dual-structure z-slot antenna with optimal isotropic pattern were the standard antenna in the horizontal direction, the designed antenna direction 90 ° and design conditions of the dual-structure z-slot antenna on the radiation plate that were the diagonal length (L = 80mm), line length (d = 30mm), the slot interval (t = 6mm) From these results, It showed to improve the sensitivity of the antenna, as well as to improve the antenna efficiency through characterization analysis of the dual-structure z-slot antenna for the UHF RFID Reader with optimal isotropic pattern.