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At present, variable RF filters to vary the filter characteristic in a wide frequency range are strongly required. We have developed a variable band elimination filter (BEF) consisting of a variable capacitor and an inductor. The variable capacitor consists of eight capacitor cells, each of which changes the capacitance by filling the gap between two electrodes with pure water. This permittivity change due to filling water has the capacitance change ratio (CCR) of 80 in theory. A fabricated variable capacitor was measured to have a CCR of 31. The decrease from the theoretical value is caused by a parasitic capacitance. A fabricated BEF was also measured to vary the elimination center frequency from 4.52 to 0.92 GHz, as each capacitor cell was filled with water. This fact indicates that the filter frequency change ratio of 4.9 was successfully achieved. Such a large value of the CCR will be expected to expand MEMS filters in many mobile applications.