Compact Quad-Wideband BPF Based on Dual-Stub Step Impedance Resonator with Meandering Structure

Some problems that appeared in designing wideband bandpass filter (BPF) using microstrip are large size, difficult structure, the filter parameters are large and too complicated, and have narrow passband. In order to overcome some of these problems, a compact quad-wide fractional bandwidth (QW-BPF) using stub step impedance resonator with meandering structure is proposed, designed and analyzed in this paper. The proposed resonator is constructed by dual-stub step impedance resonator (DS-SIR) to produce several transmission zeros with four wide passbands and good transmission coefficients. In order to reduce the filter size, a meandering structure also was proposed. This QW-BPF achieves good transmission coefficients/ wide-fractional bandwidth of 0.59/58.36, 1.16/34.55, 1.67/16.44, and 2.43 dB/15.42% at 0.85, 1.65, 2.54, and 3.43 GHz, respectively. The experimental verification was tested and implemented practically. The simulation and measurement result has a very good agreement. The proposed QW-BPF has wide-fractional bandwidth, good transmission coefficients, ease of fabrication, and compact size. The simulated and measured reports are provided and they had good agreement.