Design of a Planar Dual-Band Bandpass Filter

A new method to design the dual-band filter has been proposed in this letter. This filter is developed with two stepped impedance resonators. Two ends of both resonators are mutually coupled. Transmission zeros then appear on both sides of two passband skirts and in the rejection bands. In addition, the design equations are also provided. In conclusion, the agreement between measurement and the full-wave electromagnetic simulation validates the proposed structure.