Using multilayer S-type coupled resonators to realize the 2.4G bandpass filters

A novel method for designing bandpass filters has been proposed in this paper. The design concept is to minimize the area of coupled resonator filter by using some special method. By adjusting the distances between S-type resonators and the positions of mixed coupled filter, the coupling coefficients are controllable, which can be produced in the lower stopband or the upper stopband. To verify the concept of filters, we use the full-wave numerical method and equivalent circuit models which are used to research the characteristics of the proposed multi-layer resonators.