Research On Technology Of Radio Frequency Identification Reader System

Radio Frequency Identification technology has already found widely applications now, however, the research of the source of passive tag and transmission in RFID system has great significance. By research of electromagnetic coupling in inductive field of antenna, the paper gives the basic condition of coupled energy between high frequency magnetic in space. It uses Mifare1 S50 card, MF RC500 radio frequency module chip and the antenna matched with MF RC500 to design RFID system. This thesis has carried out the following studies:1. By analysis of inductive field, near-field radiation field, far-field radiation field around antenna, it uses ANSOFT HFSS software to make simulate the electromagnetic energy distributing in inductive field of antenna, and gives the intensity and distributing of magnetic field when the energy is coupled between the antennas.2. Basing on the function of MF RC500 chip, the paper designs the RF card's reader. It utilizes the Visual C++ software to exploit the control program which is used to control MF RC500 chip by AT89S52, and uses the Protel 99SE to design the interface circuit between AT89S52 and MF RC500; it uses RS232 seral communication module to complete the communication between the PC and AT89S52; it adopt the direct matching mode with MF RC500 to design the antenna and the circuit to match antenna.3. By applying the vice-carrier load modulation to get the frequency of signal which is from RF card to reader changed, it solves the signal interference when the card communicates with reader.4. It uses Visual C++ serial communication program MSComm to design the test programme in PC, which is used to test the function of RFID system. The test has proved that the designed reader can read the RF card effectively. The electromagnetic coupling distance is about 6cm.The designed RFID system in the paper works steady, deals with data fast, and is high reliability. It meets the need for practical applications. In the future, for the development of the long range RFID technology, the research of UHF, long range identification and wireless coupled energy is significant.