Sharp-rejection quad-band bandpass filter using meandering structure

A quad-band bandpass filter using a meandering structure is proposed. The proposed filter consists of two sets of stepped-impedance resonators with meandering structures and a pair of feeding lines with four-diverged shape. Considering the design freedom and circuit size, each pair of resonators determines two passbands. The advantages of meandering structures include generating two transmission zeros for better passband selectivity, suppressing the harmonic passband, and reducing the circuit size.