Research And Design Of UHF Rfid Reader Antenna And Tag Antenna

Reader antenna and tag antenna with high quality contribute much to the read distance and system performance. In reader antenna design, impedance characteristics, antenna gain and axial ratio are three key parameters. In tag antenna design, impedance characteristics, antenna gain, and radiation pattern are three parameters that attract most concern.This paper focuses on reader antenna design, tag antenna design and measurement of symmetric tag antenna.A compact and circularly polarized reader antenna is designed using corner-truncated square patch antenna. The antenna is suitable to handheld devices, and the measurement results agree well with simulation output. As a conclusion of this part, the procedure of designing circularly polarized reader antenna using corner-truncated square patch if provided based on design experience.In tag antenna design part, the impedance match method of using an inductively coupled loop is another research point of this paper. In this paper, the equivalent circuit and theoretical impedance formula of antenna designed using inductively coupled loop method are obtained using transformer theory. Simulation results by IE3D show agreement with formulas. This part concludes at the general procedure of designing tag antenna using inductively coupled loop method.In tag antenna testing phase, after the theoretical analysis of scattering parameter method, the impedance characteristic of an antenna prototype is obtained, which agrees well with simulation output. The implementation of scattering parameter method on a broadband bow-tie ground penetrating radar antenna gives confidence of using this method to measure broadband symmetrical antenna impedance.