This paper presents the proposal and design of multistate diplexer on uniform- and stepped stub-loaded resonators, that is, a three-state diplexer (TSD) and a four-state diplexer (FSD). The two proposed diplexers have an attractive application in a frequency-hopping system with miniaturization in their overall size. Next, three and four sets of second-order bandpass filters are applied to form the three and four filtering channels, respectively. These filtering channels are then used to comprise these multiple-state diplexers. In this way, compact size and high-frequency selectivity have been well achieved. For the purpose of demonstration, the prototypes of TSD and FSD are fabricated and measured. The measured results are found in good agreement with the simulated results.