A radiofrequency identification system for the 60 GHz ISM band ; Um sistema de identificação por radiofrequência para a banda ISM dos 60 GHz

Dissertação de mestrado integrado em Engenharia Biomédica (área de especialização em Eletrónica Médica) ; Over the past decade, there has been an increasing interest in mm-wave wireless broadband systems and enabling technologies. This consistent effort has been motivated by the foreseen opportunities for V-band (40 to 75 GHz) technology in the market of broad consumer electronics. This frequency band could change the way we experience wireless communication at home due to some unique features. 60 GHz is placed in an oxygen absorption peak, meaning high attenuation takes effect, adding advantages such as high frequency reuse and improved security due to the difficulty of eavesdropping. Also, and on a more relevant note, mm-wave operation allows for the development of unprecedented ultra-small antenna arrays and integrated transceiver modules for applications where small footprint devices are of utmost importance. In this dissertation we apply millimetre-wave technology to implement a radiofrequency identification system and show how it can be used for tracking retained surgical instruments and sponges. Retained foreign bodies after operative interventions are considered a preventable mistake. However, literature shows that they’re still an occurrence in hospitals worldwide because current prevention methods rely on human performance. Technology-supported approaches, namely by radiofrequency identification (RFID), is a logical solution to the problem. By placing a small tag in the surgical objects, they could be identified by a reader device in a base-station. Establishment of 60 GHz link was successful up to distances of 5 meters using a commercial V-band converter without the usage of antennas. A frequency multiplexing strategy was used to code a binary sequence into the signal. Also, a downconversion and rectification system was employed using off-the-shelf and DIP components for RF-to-DC conversion, in order to reproduce the transmitted sequence at reception. A feasibility study was made in relation to the ...