earticle

영어

A systematic approach to determine the extreme value of total electrical length for tri-section stepped impedance resonator (TSSIR) is proposed in this paper. It utilizes the Lagrange multipliers method to search the extremum condition. Result demonstrates that the maximum resonator length of TSSIR is limited to triple that of the corresponding uniform impedance resonator (UIR). Spurious resonant frequency of λ/2 TSSIR is mainly analysized under the extremum condition (θ1≠θ2≠θ3). Through comparison between the proposed approach and previously assumed condition (θ1=θ2=θ3), the staircase discontinuity of transmission line can be reduced using the paper theory to achieve same harmonic ratio. Last, a simulated example is presented to verify correctness of the method. This paper aims to provide a theoretical basis and general guideline for the filter design using TSSIR.