Characterization of Harmonic Signals Backscattered by Conventional UHF RFID Tags

This paper presents the impact of the non-linear behavior of UHF RFID chips on the backscatter radiated signals by commercial RFID tags. In particular we analyze and quantify the power level of the third harmonic backscattered signals by the tags. The study shows the presence of a third harmonic signal for all tested UHF RFID tags, including tags equipped with the most recent chips. The measurement shows that the level of the radiated third harmonic signals is strong enough to be detected and potentially processed. In addition, if the radiated power of the third harmonic signal varies from one tag to another having the same chip and different antennas, this variation is minor considering identical tags.

I. Introduction

The UHF (Ultra-High Frequencies) RFID (Radio Frequency Identification) technology is nowadays a very popular technology mainly used for the identification of objects, animals and people. According the target application and the considered environment, various implementation strategies exist and allow the improvement of the detection efficiency which is a key criterion for the system performance [1].