ABSTRACTA novel common mode suppression network (CMSN) for balanced structures is presented. The structure is a symmetrical transmission line loaded with λg/4 stubs, where λg is the guided wave length at the frequencies to be suppressed. The CMSN is a circuit that can be independently designed to improve the common mode (CM) behavior of the attached circuits without degrading their differential mode (DM) performance. As an example, a balanced bandpass filter (BBPF) with an undesired 0dB CM peak is improved in more than 30 dB, whilst the DM bandpass is barely affected. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:2466–2469, 2016