UHF RFID Antenna Impedance Characterization: Numerical Simulation of Interconnection Effects on the Antenna Impedance

A major design criterion of wireless communication devices is the matching between the impedance of the analog frontend and the input impedance of the antenna structure. Especially for passive communication systems, the matching is essential to ensure good performance. Numerical design tools are typically utilized in the antenna design process to determine the antenna impedance. Additionally, measurements on prototype designs are carried out to verify the simulation results. Frequently, vector network or impedance analyzers are used to measure the impedance of the antenna design. Regardless of the measurement device in use, a connection between it and the device under test has to be established. In this paper, the interaction between the interconnection structure and the antenna under test is investigated. Special attention is paid to the influence of the interconnection structure on the antenna impedance obtained. The investigations are carried out on a typical test problem by numerical field simulations by means of the finite-element method.