Tri‐section stepped impedance resonator with adjustable length and improved second harmonic characteristics

Abstract

AbstractIn this study, we present a novel tri‐section stepped impedance resonator (SIR) with two different lengths (θ1 and θ2). The lengths of the first and the last transmission lines of the proposed tri‐section SIR were intentionally chosen. We compared the properties of the proposed SIR and the existing SIR. In the same impedance ratios (K1 and K2), the second harmonics of the proposed SIR were improved by 1.05‐1.11 times compared to the existing SIR. In addition, the length of the first transmission line, θ1, could be extended by more than twice the length of the existing SIR. That was very advantageous for tight coupling in a coupled line. Finally, a parallel‐coupled line band‐pass filter (PCL BPF) was developed using the proposed SIR, and the design equations were derived. The second harmonic of the PCL BPF was measured with an error of 2.67% compared to the theoretical value. The center frequency was almost identical. A series of processes, including design, simulation, fabrication, and measurement using the proposed structure, was carried out. An analysis of the results of each step proved the validity of our proposal.