Research On Ultra-Wideband Chipless RFID Ranging Methods

Chipless RFID has the advantages of low cost,long life and high stability,which make it have application value and attract the attention of many scholars.Without complicated electronic components and battery equipment,its coding capacity,reading distance,and reading capacity are reduced.If the chipless RFID tag can be accurately located and then the tag information is read one by one using the high gain antenna,the problem of short reading range and poor reading capacity can be solved.Therefore,the research of this master thesis is the method of ranging and localization of chipless RFID tags.The innovations of this master thesis are as follows.1.For chipless RFID tag working in the ultra-wideband,a method of extracting coding and distance information of the tag based on group delay is proposed.Compared with the method of using matrix pencil method to extract tag information and extracting tag information from frequency domain,this method is more stable and accurate.2.A ranging method based on the characteristic of destructive interference is proposed.A distance measurement structure for ranging is proposed,which consisted of an antenna and a reference plane whose position is known in advance.The distance between the tag and the antenna is calculated by using the frequency of destructive interference caused by the tag scattering wave and the reference plane scattering wave.3.A method for judging the similarity of adjacent two pulse signals is studied.The frequency of destructive interference is determined by the frequency of minimum value of the energy spectrum.The similarity of two pulse signals is judged by the uniformity of the frequency of destructive interference.This method is used to distinguish structural mode response and tag mode response,and improves the stability of innovation 2.4.According to innovation 3,a method of extracting structure mode response and antenna mode response is proposed.Searching for the end position of the second chipless RFID tag structure mode response in time domain using an extended rectangular window.Using the sliding rectangular window to search for the rest structural mode response.The method is also used to solve collision problems and extract tag information.5.The relationship between the resolution of circular localization system,the number of readers and the resolution of the reader is analyzed by using functional curve and geometry.Experiments verify the relationship under specific conditions.