The Design And Implementation Of Wideband Circle Polarization UHF RFID Reader Antenna With Impedance Matched Easily Advantage

Since the "Internet of Things" has been proposed,UHF RFID(Radio Frequency Identification of Ultrahigh Frequency)technology has enjoyed exponential growth rely on its advantages of long communication distance,fast communication speed,strong anticollision capability,and low cost.Reader antenna as an important part of the UHF RFID system,obtained a wide-bandwidth circularly polarized(CP)and easily impedance match features,can simplifies the complexity of the antenna optimization,increases the recognition distance and flexibility of the system for linear polarization,low gain and passive tags,and expand the areas where the system can be applied.Therefore,a broadband CP UHF RFID reader antenna with the impedance match easily advantage be proposed in this article.The specific work is as follows:Firstly,a circular polarization UHF RFID reader antenna with the impedance match easily advantage is presented.The antenna is a rectangular microstrip patch antenna,an annular gap is adopted to obtain an advantage of easily input impedance match,a square truncation of the radiation patch is used to realize circular polarization radiation.Moreover,air substrate is used to achieve higher gain.The-20 dB return loss bandwidth of the proposed antenna is 870-978 MHz,and 3-dB axial ratio bandwidth is 902-928 MHz,and the minimum gain level in circular polarization band is 8.1dBi.Secondly,a broadband CP UHF RFID reader antenna with the impedance match easily advantage be proposed in this paper.A stacked patch microstrip antenna structure is used to expand the circular polarization band.Moreover,the annular gap impedance unit is adopted to ensure the advantage of easily input impedance match.The-10 dB return loss bandwidth of the proposed antenna is 800-900 MHz,and 3-dB axial ratio bandwidth is 860-940 MHz,and the minimum gain level in circular polarization band is 8.3dBi.The proposed reader antenna in the article have good comprehensive performance,can be used in commercial system.