Theoretical Analysis Of The RFID Positioning System Based On The Phased Array Antenna

As a non-contact automatic identification technology, the Radio frequencyidentification (RFID), which gets the advantages of non-touch, no light of sight andlow cost, has been widely used in industry, military, daily commodities, commoditycirculation, remote monitoring, etc in recent years. With the development of radiofrequency identification technology, its application range is rapidly expanding.But itsapplication of the existing RFID positioning system is largely limited due to the poorpositioning accuracy and the high complexity.In this paper a new type of RFID positioning method was researched. Themethod is a hybrid localization method which combines the AOA and the RSSI, firstlythe azimuth angle of the target label is measured based on phased array antenna,andthen the distance is calculated according to the power measured with the reader,finallythe position of the target lable is determined. The principles and advantages of thismethod are elaborated on in this paper, and the radiation characteristic parameters ofthe phased array antenna are calculated, analyzed and discussed for different antennaunits number N, antenna units space d and antenna units phase difference.Also, theeffect of the antenna unit number to the power and the SNR shows that the RFIDpositioning system with the phased array antenna not only expands the working scopebut also improves the anti-jamming capability. Based on the analysis, two feasiblearray antenna scenarios which could be used to the RFID positioning system aredesigned. Both of the two design schemes only require a reader, a group of phasedarray antenna.They can effectively track the coordinate position of the target label andgreatly reduce the complexity of the RFID positioning system with improved locationaccuracy.Based on the phased array antenna, a simple RFID positioning system is built onRMU920reader for verifying the function of this hybrid localization method, and theexperimental results confirm the location method which combines the AOA and theRSSI is feasible.