A compact trilayer triband bandpass filter using SIR‐DGS and open‐loop resonator

Abstract

AbstractA compact trilayer triband (TLTB) bandpass filter (BPF) is presented in this article. The proposed TLTB‐BPF consists of three layers which are two transmission lines on the top layer, open‐loop resonator on the middle layer, and the stepped‐impedance resonator (SIR) defected‐ground structure (DGS) on the bottom layer. The center frequencies of the low band and high band determined by the SIR‐DGS are 1.8 GHz and 5.8 GHz, respectively. The center frequency of the middle band which performed by the open‐loop geometry structure is 3.5 GHz. The measurement results of the insertion loss S21 are −0.97 dB, −2.8 dB, and −3.8 dB at 1.75 GHz, 3.48 GHz, and 5.81 GHz, respectively. The return losses S11 are −13.2 dB at 1.75 GHz, −17 dB at 3.48 GHz, and −11.1 dB at 5.81 GHz. The substrate material for fabrication is an FR4 PCB with a dielectric constant of 4.4 and a thickness of 0.8 mm. The etched size is 36.9 mm × 11.5 mm. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2751–2754, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23791