A new approach to design compact tunable BPF starting from simple LPF topology using a single T‐DGS‐resonator and ceramic capacitors

Abstract

ABSTRACTIn this article, a novel very compact DGS lowpass filter (LPF) and reconfigurable bandpass filter are proposed. The designed filter consists of one T‐DGS resonator, which is excited by 50 ohm microstrip line, placed on top layer between the input and output of the proposed structure. The selected filter topology has several advantageous compared with the other previous works such as the compactness and its simple design. The addition of compensated patch capacitor improves the low insertion loss and ultra‐wide stopband with 15 dB attenuation from 2.2 to 3.6 GHz. The size of the proposed single T‐DGS LPF‐BPF is less as (0.023 λg × 0.044 λg) with λg = 0.263 m. The tunable bandpass filter (BPF) is extracted from LPF topology using variable Chip Monolithic Ceramic Capacitors and J‐inverter technique. Finally, the measured, EM‐ and field simulation results are presented and discussed. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:1142–1148, 2016