| Measurement technique is crucial for science development, without measurement technique there would be no science. Voltage,current and impedance are the basic measured parameters in DC circuit or low-frequency(LF) circuit, and measuring the Radio Label Impedance is important to the application of radio frequency. With the rapid development of RFID, Radio Label Impedance Measurement plays a more important role in this field. This paper mainly researches and accomplishes Radio Label Impedance Measurement of high accuracy and easy-test based on LabView.Firstly, analyzes the development and the current situation of RFID, and give an account of RFID theory at UHF frequency, then points out the significance of Radio Label Impedance Measurement.Secondly, introduces the concept and features of VI (Virtual Instrument), as well as its development, evolvement and constructing technology. In addition, the LabVIEW developing platform is introduced, including Graphical Programming Language, concept of VI, characteristic of LabVIEW and normal procedure of LabVIEW program design.Thirdly, based on the characteristics of antenna radiation field, the conditions of backscatter modulation RFID technology namely the antenna far-field working conditions are given. Then makes a systematic description of impedance, polarization mode, directivity of an antenna. And discusses the theory of microstrip antenna, transmission line method, Working Principle of RF-tag.Finally, puts forward that the measuring of radio frequency label impedance ,it is realized by matching network.Known the load impedance, matching the load impedance and the internal label impedance and determining the matching coefficient, then work out the internal impedance. Subsequently, designs a circuit of impedance measurement applying the Labview technology, detailed analyze each parts of the circuit first such as phase meter and the scope comparer, and at last makes a simulation analysis of the total circuit. |
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