Detection of closely-spaced objects by a low-cost reader at 2.45 GHz

A new long-distance microwave reading system is introduced, that we shall call RID (Remotely Identify and Detect), able to locate and identify objects in harsh indoor environments. This is obtained by augmenting standard RFID reader operations with the mono-pulse RADAR principle and electronic beam scanning capabilities. In this way reading failures due to operation in severe fading environments are effectively overcome. The technique is experimented at 2.45 GHz and may be frequency-scalable: the higher the operating frequency the closer can be the tags to be detected. The system is realized by a suitable combination of custom designed components, such as a double printed-monopole array with electronic scanning capability, and of low-power commercial transceivers and MCUs. This results in an handheld low cost device with total dimensions comparable with typical PDAs. The system capabilities are demonstrated in indoor scenarios locating and selecting closely-spaced tagged items, fixed or moving. From this view point RID could be an answer to the intense research and industrial interest solicited by the needs of interacting with systems of devices, such as sensors and actuators, capable of improving the living conditions both at home and in a work space.