Design of microstrip lowpass filters with wide stopband and high attenuation

In this reported work, novel microstrip lowpass filters featuring wide stopband and high attenuation have been developed. These filters are composed of multiple open stubs and short-end coupled lines. By properly selecting the electrical lengths of the open stubs and short-end coupled lines, transmission zeros can be generated in the vicinity of harmonics and a wide stopband can be obtained. Detailed design procedures are provided; moreover, agreement between measured and theoretically predicted results demonstrates the feasibility of the proposed filter.