Near field focusing circular microstrip antenna array for RFID applications

FREE-DOWNLOAD R Siragusa, P Lemaitre-Auger… – … and Propagation Society …, 2009 RFID (Radio Frequency IDentification) is an identification method based on electromagnetic waves communication between a reader, also called base station and a tag [1]. It constitutes a technological breakthrough that is revolutionizing methods of identification and traceability that are among the major concerns of industry. RFID systems have to work in constrained environment with low power level. In that context, the efficiency of the transmission is crucial. To solve this problem, focused system can be a suitable solution that could also be use for localization applications. In the past, RadioFrequency (RF) systems were developped to control the beam of antennas. High directivity can be obtain with phased array . Space scanning systems were developped for radar applications with RF lenses . More recently, Metamaterials antennas like Composite Righ/Left Handed (CRLH) Leaky Wave Antenna (LWA) can achieve full space scanning and high directivity. But only few solutions with real focused beam were developped. In , a square array is used to focused at 12 GHz for sensor applications like the characterization of substrate. This system allow a focal point at 126 mm with 16 antennas but its design is tedious due to a complicated feeding network. Indeed, each antenna has to be feed with a particular phase. In this paper, we proposed a circular array for RFID applications with a simple implementation and low side lobe level compared to a square configuration. First, the theory of the focused system is developped. Second, the implementation of our system and the measurement setup is presented. Then measurement results are shown and discussed. Finally the last section conclude the paper.