Antenna Array Synthesis for RFID-Based Electronic Toll Collection

This paper deals with the synthesis and design of reader antenna for radio-frequency identification (RFID)-based dedicated short-range communication (DSRC) systems. A method for synthesizing a planar antenna array with both the aim of stretching the communication area toward the longitudinal direction and confining it within a certain number of road lanes is described. This method can be used for any working frequency, and two synthesis examples are described taking into account requirements and system parameters of the standards electronic product code (EPC) Gen2 in the ultrahigh frequency (UHF) hand, European ETSI EN 302 663 for intelligent transportation system/DSRC, and Chinese GB/T20851-2007 for electronic toll collection/DSRC at 5.8 GHz. After that, the design of a specific 4 x 4 planar antenna array for the case of a UHF EPC Gen2 Chinese band 920.5-924.5 MHz is reported. Microstrip technology is chosen for its advantages of being light, simple, inexpensive, and easy to manufacture. The proposed design presents good matching characteristic and bandwidth, and effectively synthesizes the required communication area (also in the presence of an external radome). Measurement results performed in an anechoic environment together with the experimental verification of the synthesized communication area confirm the validity of the proposed method.