International Symposium on Antennas and Propagation
A Trial Direction Finder for the Passive RFID Tag
H.Nakamura, Y.Kuwahara, M.Kai,
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We are studying about high functionalization of passive RFID reader/writer of 2.45GHz band . If a tag was located and was tracked by the high-gain scanning beam, communication range is extended without increasing transmitter power and interference between tags is also avoided. If the direction finding capability is provided to the RFID reader/writer, then it is possible to find the position of goods with the RFID tags. In this case, it is also desirable to form the high gain beam and to scan it for large searching area with power saving. In this paper, we present a prototype of the direction finder with the capability of estimating a passive RFID tag. Multi-beams are formed by the Butler Matrix and are switched in order to provide a high power density to tags distributed to the large area without enhance of transmitting power. The antenna aperture is a 16 element planar array of Microstrip-Patch-Antennas (MSPAs). Element space MUSIC is used for direction of finding estimation.