A compact quarter-wavelength stepped-impedance resonator bandpass filter with source-load coupling

Abstract

In this paper, a compact quarter-wavelength stepped-impedance resonator bandpass filter is proposed, two extra transmission zeros are implemented by source-load coupling between the feedlines, a filter with two resonators is designed, each resonator consists of a low-Z section and a high-Z section, good performance is achieved both in passband and stopband. Demonstrator filter is designed on the Rogers RT/Duroid 5880 dielectric substrate, centered at 5.8GHz, and the BW is 400MHz. The measureted result shows that RL in passband is less than 15dB, and the minimal IL is 3.0dB. This filter occupies an area of 6.55mm×2.85mm. The demonstrator filter is fabricated, and good agreement between measurement and simulation is achieved.