RFID (Radio Frequency Identification, RFID) is a way of using Radio Frequency for non-contact two-way data communication, in order to achieve the target recognition and data exchange technology.RFID CARD system generally consists of label, read and write device and computer communication network. Label store of information to identify objects, attached to the unknown object. Usually electronic tag accord with standard of IS018000-4 and 18000-6, passive itself, through the read/write device of radio frequency (rf) field access to energy, adopts the load modulation method. Read and write device using rf signal the read/write tag information and processing.
PC remote control with RS 232 interface to read and write. Read/write device after received orders, sent via antenna rf command implementation to the operation of the tag, at the same time receive the data returned tags. Electronic tag on its internal antenna gain energy and controlled by the chip (IC) receiving, sending data. Domestic combo cards system using spectrum is mainly divided into low Frequency (below 135 kHz), High Frequency (13.56 MHz), UHF (Ultra High Frequency, UHF) (860 ~ 960 MHz) and microwave (more than 2.4 GHz) and so on several major categories. Currently, more and more research focused on the study of UHF RFID system.
Caused by the electromagnetic wave will be metal reflect common electronic tag on the metal surface cannot be identified correctly, this defect seriously limits its wide application in logistics industry, thus UHF tag antenna of metallicity became the research hot spot and conquer the difficulties. Based on the analysis of the influence that metal tag antenna electromagnetic field, on the basis of a relatively low cost can be used for metal environment of uhf passive contactless cards tag antenna. It will ring microstrip antenna and the dipole substructure combination to realize the characteristics of the high gain in metal environment. Antenna area 100 mmx40 mm meet requirements of small size metal environment, has the high cost performance.
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