关键词: 双频带带通滤波器, 微带滤波器, 非对称阶梯阻抗谐振器

Abstract:

A compact dual-band bandpass filter was designed and developed based on asymmetrical stepped impedance resonators (SIR) for the realization of miniature dual-band bandpass filtering in mobile base station. The two central passband frequencies and bandwidths of the proposed filter can be adjustable by geometric parameters. A folded stepped impedance resonator modified by adding an inner quasi-lumped SIR stub was used as the basic module of a new configuration of dual-band bandpass filter to produce two different passbands. The first pass-band of the filter only depends on the dimensions of the external SIR, while the second passband depends on both the external SIR and the quasi-lumped stub. A dual-band filter operating at 0.9 GHz and 1.8 GHz was designed, fabricated and measured for the application of mobile phone base stations. The dimension of the proposed filter is 24.76 mm × 13.5 mm. The experimental results show that the measured S parameter fits very well with the simulation. The effectiveness of the proposed design method was validated.

Key words: dual-band bandpass filter, microstrip filter, asymmetrical stepped impedance resonator