AbstractUsually, the resonant filter is composed of several resonators made of dielectric and metal, and is applied to high‐frequency bandpass filters (BPFs). Although a resonant filter has a simple structure, it is very difficult to obtain the optimal geometry experimentally, because its filter characteristic is greatly influenced by the material and the structure. This paper presents an analysis method for the high‐frequency resonant filter by using the method of moment (MoM). The computed characteristics of the resonant filter are in good agreement with the measured ones. Furthermore, the influences of design parameters of the filter on the characteristics are investigated. © 2009 Wiley Periodicals, Inc. Electron Comm Jpn, 92(4): 42–48, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecj.10053